Do-it-yourself UPS

Giampiero writes "Over at dansdata.com some guy named Dan creates a UPS out of some spare parts. To sum it up, "if you're looking for an industrial-capacity UPS solution, and don't like the prices of the off-the-peg options, it might be easier than you think to roll your own."" Of course you can mentally substitute U.S. 110 volts for Australian 220 volts wherever necessary...

Comments

I want a UPS!

[apoKalypse]

I hope its excessively cheaper than normal UPS' that you would buy, that would be a cool thing to build.

Re:I want a UPS!

[plover]

According to the article, his solution can be any amount of money you care to spend, from less than an off the shelf APC ($90 USD for a small one) to far more than your PC cost you.

You'd probably get more bang for the buck though if you already owned some of the components, such as a decent marine battery or a 25A power supply.

His article was more to say that if you roll your own, you can stack up a basement wall full of lead-acid batteries and run your PC for a week offline if you want. And you can do that cheaper than you can buy a real industrial power supply.

Re:I want a UPS!

[cscx]

I doubt that. You can pick up an APC Back-UPS 500 for $100 USD if you look hard enough. Places like Staples often have them on clearance.

Plus, APC adds filtering components and surge protection. I think there is a guarantee on the components hooked to it too. I had a Cisco router hooked to an APC Back-UPS once during a bad thunderstorm. People lost equipment all over the place during that storm, and I lost the UPS... it was DEAD. But it saved the router, which was more important!

Also, you get serial port communication for logging too. Sometimes it's nice to know that, well, damn, why DID the power go out at 4:30 AM?

Thanks but no thanks... I'll be sticking with my trusty APC. =) But this is a cool idea nonetheless.

Re:I want a UPS!

[Anonymous Coward]

Look, it's your brother --> -- haha!

Re:I want a UPS!

[Anonymous Coward]

There is nothing keeping you from hooking up a line condition (although usually expensive) or standard surge protector after the DC-AC conversion point. A decent consumer surge protector is around $25, frequently less.

Likewise, with power monitoring, someone just needs to figure out how to monitor DC voltage and communicate with a serial line. In fact, I'd fathom there's some tool out there now. Then it's a matter of a program (simple perl script polling a serial port) to figure out status to initiate shutdown.

Really, the only problems with this idea is getting quality components, and the ability to disperse any potentially hazardous gases....not
really easy, but also not impossible for DIYers.

Re:I want a UPS!

[matguy]

Also, what's stopping you from taking a cheap APC, pulling the little Gel Cell battery and plugging in a big ass Wet Cell? (or a few wet cells in paralell)

Re:I want a UPS!

[jo42]

Hmmmm... Mebbe a wee matter of the charging circuitry not knowing WTF to do with a big ass Wet Cell?

Awesome!

[LaserBeams]

APC's estimator tells me I need a $1500 UPS for my computer and all it's gadgetry - but I have nowhere near that amount of money. This sounds like a viable option!

Re:Awesome!

[sharkman67]

I use TrippLite power inverters with marine deep cycle batteries.

I have a 24 and 36 volt inverters. To add additional capacity all I need to do is add more batteries. The only thing to make sure is that ther e is proper ventalation for the batteries.

The inverters have ports for remote management as well as status leds.

It is a much lower cost solution and not as risky as there is not really high voltages.

Re:Awesome!

[glitch!]

I have a 24 and 36 volt inverters. To add additional capacity all I need to do is add more batteries. The only thing to make sure is that there is proper ventalation for the batteries.

Even though you specifically mention that you provide ventilation, I bet you will still get people yapping at you that your setup is dangerous because of the hydrogen :-)

Just out of curiousity, how do you connect the batteries together? Do you use ordinary automotive cables connected to two huge bus bars? Or do you have some fancy connection blocks? I thought about doing something like this myself, but I never saw any really elegant way of connecting the batteries together.

It is a much lower cost solution and not as risky as there is not really high voltages.

The current can be absolutely amazing, though! I might not be so worried about touching an exposed contact, but I would be paranoid about letting any kind of metal object anywhere near the battereies!

Re:Awesome!

[eXtro]

Most of your gadgetry doesn't need to be on the UPS (though it should have surge protection). A UPS isn't there so you can work through a black or brown out, its there to let you shut down in an orderly manner. Scanners, amplifiers, printers and the like aren't necessary for an orderly shutdown. Even a monitor isn't necessary if you've got a serial port on the UPS and monitoring software on your box.

I've got two computers running off an inexpensive APC UPS. I've only had the computers start the shut down process twice, and the area I'm in has at least a few power outages per year.

Re:Awesome!

[BLAG-blast]

Even though you specifically mention that you provide ventilation, I bet you will still get people yapping at you that your setup is dangerous because of the hydrogen :-)

To a large extent the danger of explosion can be reduced by using hydrogen catalyst battery caps on all cells of the lead acid battery. These can be purchased from Hydrocap, 975 N.W. 95 Street, Miami Florida, 33150,(305)696-2504.

Re:Awesome!

[sharkman67]

The batteries are connected with heavy gauge wire (I can't remember off hand but it might have been 0). The wires end in lug connectors which fit onto the terminals and secure with wing nuts. Since the batteries are so close together the wires are only between 4 and 8 inches. The 24V UPS is mounted in a 19in relay rack. The 4 batteries are on the base and the inverter is on a shelf above the batteries. The next level on the rack is a 16 socket TrippLite rackmount power strip. All equipment is mounted above on other shelves. The battereis are protected by plexiglass covers that prevent fingers, tools or anything else from accidentally shorting any of the terminals.

The 36V UPS is actually mounted in a an old Exide UPS case that once powered a mainframe from my old company. When they put in a RS6000 and retired the old system I took the UPS home. The old UPS was a 120V DC UPS with a huge transformer (obvious as it did a 1 to 1 AC to DC conversion). The unit weighed about 400 lbs. I used it for a while until the batteries died (6V Yuesa gel cells in series). I replaced them with the marine batteries. Eventuall the inverter board died (probably old capacitors) and rather than play with the HIGH voltage I gutted the inverter module and put in the TrippLite. The rest of the unit is still in production. Including the 30amp breakers for each of the eight power sockets and voltage monitors. The case it really pretty cool and has big geek factor.

Re:Awesome!

[jdii1215]

Actually, I am considering about 1500 watts of UPS, but I only need 10-15 min of failure power.

The article was nice, and informative.

Be Careful

[TibbonZero]

Please, everyone take caution when working with high voltage and moreso, high ampre compenents. We don't want any fried ./ers

Re:Be Careful

[GigsVT]

People often misunderstand the electrocution hazards presented by electricity. Yes, technically it's the amps that hurt you, but the volts have to be there too.

I could hold a 1 volt 300000 amp power supply's leads all day and not be hurt. The reason is Ohms law.

Your body generally has a pretty high resistance. Ohms law states that amps=volts/resistance. Your body is probably between 20,000 and 300,000 ohms, depending on which part you are talking about. Wet or sweaty parts have lower resistance. Higher voltage is more dangerous, because more amps will flow through your body. A 500 volt at 1 amp power supply would probably be lethal, especially if you had wet hands.

A rule of thumb is that anything above 50 volts should be treated very carefully. This is about the threshold of where you will normally start to conduct possibly dangerous amounts of current. If your hands are sweaty or wet, or you are grounded well for some reason, better cut that down to 30 volts.

Here's a link

The parent post is correct though, be careful in any case. Don't try this stuff unless you know what you are doing around electricity.

Re:Be Careful

[Anonymous Coward]

Please, everyone take caution when working with high voltage and moreso, high ampre compenents. We don't want any fried ./ers

Any person stupid enough to play around with high voltage components without knowing what they are doing deserves to be electrocuted.

Re:Be Careful

[Anonymous Coward]

Any person stupid enough to play around with high voltage components without knowing what they are doing deserves to be electrocuted.

Let me correct myself before everyone else does. The voltage doesn't matter, it's the amperage (the strength of the electric current) that kills you.

Re:Be Careful

[Anonymous Coward]

People often misunderstand the electrocution hazards presented by electricity

So what the exactly does that have to do with the batteries in question which have both enough voltage and amperage to kill a person.

Oh I'm sorry... did I rain on your "look at how smart I am" parade?

Re:Be Careful

[SandSpider]

"We don't want any fried ./ers"

I believe you mean any *more* fried /.ers. Or perhaps I've said too much.

=Brian

"We were making science, your honor."

Re:Be Careful

[Anonymous Coward]

Careful with that approach. That hefty powersupply won't hurt you a bit until you accidentally short the leads and end up with a molten mess on you hands. (Arc welders work in the 30 volt range, btw).

A more paranoid approach is to check wattages. I'm guessing that 10 Watts is probably "safe"(light burns and such). As such, this UPS heads way north of that estimate.

Re:Be Careful

[lostchicken]

A lesser known danger is that, at least on my APC BackUPS 450, when the system is on backup after one has pulled the power main to the ups (unplugged it), the male plug that would go into the wall is still hot!

I haven't measured it, but it felt like 110VAC across the prongs to me when I discovered this effect by accident. Be very careful with these things...

Re:Be Careful

[anonymous cowarad]

Whore.

Re:Be Careful

[stienman]

This indicates that something is seriously wrong with your UPS. If it did drive a current or voltage across the input power plugs it'd be powering the building grid which is not only illegal, but those doing so are liable for any damage to the power grid and associated line workers. They take just as much protection for a downed grid as a live one for stupid users who try to power a downed grid, but several die each year because someone's power went out and their generator/UPS/alternative power system was back feeding the utility company when the grid was down. Connecting two mismatched live grids together is fun for the whole family.

If your UPS is UL listed then there are several regulations which govern just this sort of action. Report the problem to APC, if they don't do anything about it (!!!) then report it to the UL and/or BBB.

I'm being completely serious. For it to go this bad there is certian to be more wrong with it. I wouldn't trust it to power anything worth more than $10.

-Adam

Re:Be Careful

[Alpha State]

It's quite possible that it was 110V! The mains AC goes through a transformer and rectifier to DC to charge the battery. The transformer can operate in reverse to generate high voltages! Although the rectifier will not work in reverse to generate AC, a voltage spike from changing the battery current could still drive the transformer. Of course, commercial UPSs should have safeguards to prevent this. Alternatively, the socket could have a loose connection creating resistance - I had one socket which gave PCs trouble - took ages to work it out as it would work when plugged into another socket. Working battery powered equipment like a UPS is not like working on a toaster - it is not safe once you pull the plug out of the wall!

Re:Be Careful

[compwizrd]

measure it, cause it's in the 30 volt range, if i remember right

Re:Be Careful

[lostchicken]

I'll do that.
A company like APC should have something in their product to keep from delivering 110VAC to my hand.

Thanks for the advice.

Re:Be Careful

[Tekgno]

I have a monitor like that, pull it out of the wall, touch the prongs and bang. It wasnt until I did it a few times that I realised that it always does it, I thought it was just a fluke.

I'm immune to electrocution anyway, autocoils, the backs of dodgy PSU switches etc.

Then there was a time I thought I found a data-port, I was on a payphone and there was this hole in front of me, wasn't until after I stuck my finger in that I realised that it was a light switch with the switch broken off. My other hand was earthed through the braided sheath surrounding the cord on the phone handset.

Re:Be Careful

[lommer]

The way to solve this is to put a diode across the "hot" lead, thus, your UPS will no longer back-supply the grid as was mentioned in another post.

Re:Be Careful

[lasthope]

Mine was already burned!

It was the most beautiful scene I've ever seen.

:-)

Re:Be Careful

[Fulcrum of Evil]

A more paranoid approach is to check wattages

Cue the story of the navy engineer that killed himself with a muultimeter (runs on a 9V). See, he wanted to measure his internal resistance (which was fairly low), so he held the leads, one in each hand, and punctured his thumbs. Long story short, he discovered that 80mA across the heart = 1 dead Seaman.

Re:Be Careful

[Phork]

Im guessing it would only do that once each time it's unplugged. Im guessing the capacitors dont have good enough bleeder resistors on them, so your hand is serving to discharge the capacitors, This could be giving 117v, it could be giving less, it could be giving 600, but more than likely it is a very low amperage. So i dont think it's much to worry about, but it is a bad design.

Re:Be Careful

[Trepalium]

It's possible and likely he got a shock from his UPS when he disconnected the plug, particularily since disconnecting it from the outlet prevented the unit from being properly grounded, but I doubt it was 110V. If he touched the ground pin, he was grounding the entire circuit through his own body.

Re:Be Careful

[Hans Lehmann]

I could hold a 1 volt 300000 amp power supply's leads all day and not be hurt. The reason is Ohms law.

You won't be electrocuted by the 1 Volt supply. Just don't accidentally drop a wrench across the terminals. Even if you do manage to get your hearing back after the explosion, you'll still have to content with the burns from the flying globs of molten metal, not to mention the effects of the sulfuric acid sprayed throughout the room when the batteries explode.

Re:Be Careful

[paxil]

I could hold a 1 volt 300000 amp power supply's leads all day and not be hurt. The reason is Ohms law.

Although what you say is mostly correct from a practical point of view, try not to forget that "ohms law" is an idealization and only applies to a small class of conductors. What G. S. Ohm noticed more than a hundred years ago what the in metalic conductors at a constant temperature the ratio of electric field to current density was approximately a constant, known as the resistivity. (note that this is a microscopic statement.) Working from this assumtion that rho=E/J, and assuming an isotropic, ohmic conductor, one easily arrives at the more familliar version of ohms law: R=V/I. Now this is a very usefull result, but please remember that it was drived only after making multiple assumptions regarding the nature of the conducting material and has noting to say with regard to what is going on at a smaller scale.

Anyways, just be carefull you don't read too much into "ohms law".

A tunnel diode is not a bad example of something you can hold in your hand which is most deffinately not ohmic and exhibits some interesting behavior because of this.

Electrochemical systems (such as collections of cells in a human body) are another good example of decidedly non-ohmic systems. Pick up a physical chemistry book if you want to learn more.

The take home point is: Yes, you could probably hold on to a 1v supply with no problem, but the effects of electricity on the body are not as simple as you make them seem.

And, No, I am not one of those people who think cell phones or power lines are harmfull :)

Re:Be Careful

[glens]

A fatal dose of electricity doesn't constitute electrocution unless it's happening to you as a form of punishment. Think "electrical execution".

Re:Be Careful

[UranusReallyHertz]

Than what the hell ARE we supposed to call "a fatal dose of electricity"? "He was accidently electrocuted." might be slightly oxymoronic, but it is a lot nicer than saying "He accidently recived a fatal dose of electricity." Besides, the term is used even when the "dose" is not fatal. A distant relative of mine was very badly injured at his construction job when some steel pipes he was carrying grounded out a crane that was obviously malfuntioning. He was brain damaged, but he did not die for many years afterwards. So was he electrocuted or not?

Re:Be Careful

[Daehenoc]

Also in regard to GigsVTs post, imagine a graph with volts on the y-axis and amps on the x-axis.
Draw line starting waaay up near the top of the y-axis, almost touching the y-axis. This line screams down the y-axis, tending away from the y-axis (on an angle of two or the degrees) and does a sharp turn right, near to the x-axis. The line then screams off up the x-axis, getting very close to the x-axis.
Now, if you suffer a volts/amps hit above the line, you can kiss your ass goodbye. If you get a hit under the line, you will probably survive, barring heart/nerve problems.

So. You can take high amps at low volts, or high volts at low amps, but not both at the same time.

(On a side note, I once grounded a live mains wire with a screwdriver (totally unintentionally, of course) and wow! that was a bang and a flash. It vapourised a 5-cent-sized piece (we are in australia here) out of the case of the power supply which was nice thick 3.5mm ally.)

Re:Be Careful

[threephaseboy]

YES! Putting a diode across an AC line is a GREAT way to rectify the power, and thus turn AC into pulsed DC. Oh wait, i'm sorry, i forgot you are a flaming idiot

Re:Be Careful

[Anonymous Coward]

Folks have told me that emperical studies show that as little as 5mA through the heart can kill. You're on the right track, sort of: you need some voltage to get through the high resistance of your skin. 12V will do the job. Just stick your finger in the cigarette lighter socket in your car if you doubt that. A friend did that, and cut himself badly on the underside of the dash when he convulsed. We were re-wiring under there, and the lighter was probably the only thing which had power. We thought that 12 Volts was safe.

An electrician friend tells me that 120V is dangerous, 220V is often fatal, and he had never heard of anyone surviving a shock from 440V. Ther e may have been some exaggeration in that last statement. 500 V at 1 Amp should be uniformly lethal, IF the current flows from one side of your chest to the other. If it's flowing from one side of your hand to the other side of the same hand, you might just cook your hand.

We used to make hotdog cookers out of two forks soldered to a powercord. We'd plug the forks into the hot dog, and the plug into the wall for a few seconds. How fast did it cook? That depended on how many Seimens in your weenie.

Re:Be Careful

[Anonymous Coward]

Isn't it the current through the body that kills? I remember reading somewhere that 20mA through the body is all that it needs to kill you. Somebody correct me if I am wrong.

Re:Be Careful

[BlueUnderwear]

but I doubt it was 110V. If he touched the ground pin, he was grounding the entire circuit through his own body.

Back in the day, I had this happen occasionnally when unplugging my Commodore 64's transformer. (No UPS, just a normal transformer). Happened only when touching it right after unplugging it, seconds later it was ok. Could have been the inductance of the transformer doing funny things.

I'm pretty certain it's far less than line voltage too, as here in Europe line voltage is 220V which would be lethal if touched in such a way.

Re:Be Careful

[david.given]

Or even low voltage, high current devices. Car batteries are designed to supply 300A at 12V. Yes, that's three *hundred* amps. And it's unfused. They warn you to take off any jewellery while working on a battery. Do you know what happens if you accidentally short, say, a wedding ring between live and ground (such as the car chassis)? The ring flashes into vapour and neatly strips the flesh from your finger. Not pretty.

Treat 'em with respect, people. Big batteries are seriously kick-ass things.

Re:Be Careful

[cjc84]

Yes, of course be careful. Even a 9 V battery can kill you if you touch both ends while you're covered in an electrolytic solution. But a spark plug wire is not lethal, even though it is 30000 V. Granted it will give you a shock, just won't kill you.

Re:Be Careful

[GigsVT]

The UPS is working fine. The manual says to never unplug the UPS when it is operating. This is because it needs a proper reference ground, otherwise the ground and chassis float with a fairly low voltage, 50-90volts. Enough for you to feel it I'm sure.

Re:Be Careful

[jhines]

The conductor that is capable of handing 300000 amps would be heavy enough for you to cause bodily harm, should you drop it on any part of your self.

Getting crushed to prove the electrical point is a great Darwin canidate.

Re:Be Careful

[apuku]

>but several die each year because someone's power went out and their generator/UPS/alternative power system was back feeding the utility company when the grid was down

I seriously doubt this. Even if your inverter doesn't have automatic line failure disconnection and/or you were dumb enough to directly wire your generator to the grid, there not much chance your 1-50kW power source can bring up the grid - even in the case of islanding. Moreover, as you say, linemen treat downed lines as live and dangerous.

The urban legend of the guy with the 5hp generator backfeeding the neighborhood and electrocuting the lineman is just that. And it makes it hard for those of us who want to supply power to the grid to get net-metering (etc.) approved by the bureaucrats.

Re:Be Careful

[GigsVT]

Hehe, good point, lets assume they were wall mounted busbars. :)

Re:Be Careful

[heh2k]

just curious, how many other people have licked 9v batteries to test them? ever lick any bigger batteries?

Re:Be Careful

[Anonymous Coward]

90% of chances that the line capacitors inside your UPS have no bleeding resistor!!!

This kind of shock is not lethal, but it hurt like hell. :-)

There is some ways to circumvent that:
- Do not touch the plug prongs for a while: some bleeder resistors are rated too high, thus the capacitors may need some time to fully discharge.
- Take a metallic rod (screwdriver, key, knife,...) and short the male plug, instantly discharging that nasty capacitor. You may see a little tiny spark, the capacitor is now fully discharged.
- Go overkill and modify your UPS, add a 100K/2W resistor across the mains lines, *After the main fuse* but this last one is definitely NOT RECOMMENDED

Re:Be Careful

[carlos_benj]

How about, "He was 'conducted' to the afterlife."

Re:Be Careful

[markmoss]

I heard this long ago in Air Force tech school, only the victim was an Airman. I think it's a myth; as far as electricity goes, blood is dilute salt water, and most everything else is dilute salt water with various membranes in the way, and I don't think 9V could put that much current through it. But it is definitely worth remembering that most of the body's resistance is in the skin - and so the jolt you get depends very much on the quality of the skin contact.

Lightly touch a small exposed 110V wire with dry skin, and you just get a little tingle. Grab a big chunk of metal in each hand, and 50V might be more than enough to freeze your muscles with your hands clamped, so you stay there and fry. That's pretty well understood, but another thing that isn't so understood is what rings, etc., can do to you. If a live wire touches the ring, the electricity reaches a much larger area of skin, and the current is multiplied accordingly (if the other side of the circuit is also a large enough or wet enough area). And you might be sweating under the ring, too.

I worked as a repair tech for six years, and because you have to power the stuff up to troubleshoot, and because it's _broken_ so the power doesn't always stay where it belongs, I've gotten zapped many times. It never hurt me - aside from minor bruises from jumping away from the electricity. The rules: no rings, no watch or a cheap plastic one, plastic instead of wire-frame glasses, watch what you're doing always, keep one hand where it can't touch metal, and brush any metal you might have to touch with the back of your hand first (so reflex will break the contact if it's hot). And learn NOT to jump when you're up a ladder...

Re:Be Careful

[markmoss]

This might not actually be dangerous (unless you jump too far when you feel that tingle and crack your head). Solid state electronics always leaks a little bit. In most power supplies, the first thing the cord goes into is a bridge diode, which converts 120VAC to about 340VDC. If these were perfect diodes they would completely block the DC from the power prongs, but since they are real devices they have a few micro amps of reverse current. This might charge the prongs up enough to feel a shock, and it might be measurable with a voltmeter, but there's no way you could get enough current to be hurt. (Except if a diode was shorted, but in most cases the device would then be quite inoperative. Of course, if you work on "broken" electronics, it's hard not to sometimes find something like this the hard way.)

Another place I've seen this is with solid state relays. Is it really switched off? Hook it up to the line, touch the output terminals with a voltmeter, and it reads nearly line voltage (440VAC the time one of our machine repairmen came running to me). Put a 100K load across it, and there's about 5 volts. The relay is indeed switched off, but because it's a block of silicon, some electrons will sneak through it anyhow.

All this gives me a real liking for those big old electromechanical relays that physically separated the input and output when they were opened. Especially the ones with springs so heavy that welded contacts would either tear apart and open, or break open somewhere else... There's no question that when those are off (which often can be visually checked), they are really off. But they are expensive and heavy, and the big ones need solid metal mounts or everything shakes when they operate.

Re:Be Careful

[Physics Dude]

So what the exactly does that have to do with the batteries in question which have both enough voltage and amperage to kill a person.

Wake the hell up! 12 Volt batteries do NOT have enough voltage to kill a person.

Re:Be Careful

[thebigmacd]

Don't quote me on this, but I once heard something about AC blasting one's hands from the place of contact and DC causing the muscles to clamp on. Something to do with the fact that the direction of current changing creates a replusive force of sorts (because of the body's capacitance?) while unidirectional current does not.

Re:Be Careful

[Fulcrum of Evil]

I don't think 9V could put that much current through it.

9V is irrelevant - it's Amps that kill, and 100mA across the heart will kill. As it turns out, the body's internal resistance is fairly low, so 9V is more than capable.

Re:Be Careful

[bitfoam]

Your body is probably between 20k to 300k ohms, for a DC current. Remember, your body is also a very effective capacitor which presents a much lower impedence ("effective resistance" for an AC current) to an AC current. The higher the frequency of the AC current, the easier it passes through a capacitor (i.e. impedence -> 0 as freq -> infinity).

30 to 50 volts DC probably isn't going to do anything to you. 30 to 50 volts @ 50 Hz AC, on the other hand, starts to get dangerous.

What makes power supplies and such particularly dangerous is that most use a technique called high frequency switching to efficiently transform your AC utility power to stable, high amperage output. Those high frequency voltages would send a current that rips right through your juicy body, composed of 80% water and salts, wonderful capacitor material.

Re:Be Careful

[GigsVT]

Yes, that is something I had forgotten to mention, thanks for pointing that out.

Finally

[Townshend]

Finally I can have a UPS on my $7 / hour budget :-)

second post!

[Bob Kronkel]

the link didn't work for me. Anyways, i wonder how much all the parts cost him? i'm sure its cheaper than buying UPS, but still...

Do it yourself UPS?

[Anonymous Coward]

I for one do not have time to truck all my packages individually across the country!

Oh ... um ... never mind.

Re:Do it yourself UPS?

[Anonymous Coward]

You don't have to use a truck, just throw the package with all your strength.

Re:Do it yourself UPS?

[jx100]

or build one of these

so will i be able to...

[neo8750]

drive the truck when i deliver my package or do I need a special license for that?

Do-it-yourself UPS? It's been done.

[TheFrood]

I've been doing this for years. I have a big brown truck, and whenever I want to send something to someone else, I just put it in a box, hop in the truck, and drive it over to them. I've even got a little portable touchpad for them to sign on, so it feels like the real thing.

TheFrood

Re:Better than paying 100 bucks for a Blackout Bus

[fidget42]

And is it just me or do I have the 3rd or so post?

It's just you.

Re:Better than paying 100 bucks for a Blackout Bus

[zorg50]

I guess it was just me...

I don't know...

[bravehamster]

..."rolling my own" world-wide shipping conglomerate sounds like a little too much work to save a few bucks on shipping. I'll just stick with Pullman Brown, thank you very much.

On the other hand, would I get to wear the little shorts? Chicks seem to dig those.

Re:I don't know...

[Anonymous Coward]

one has to ask, just to be sure

you are a chick right?

^.^

Re:I don't know...

[Anonymous Coward]

Does it matter?

Re:I don't know...

[smyle]

On the other hand, would I get to wear the little shorts? Chicks seem to dig those.

That would work for the first time, but if you want a repeat performance, the question that has to be answered is "can you really deliver overnight?"

I feel like an idiot

[God Takeru]

Because I really don't think I can figure out how to do this. And even if I could, I wouldn't have the hand skills to work with it...just because you can roll an 18 dexterity in D&D doesn't mean you have any skills.

Anyone else here, or am I just a fucking moron?

Re:I feel like an idiot

[fsmunoz]

Fear not my friend; for what it's worth you're not alone in the Moron Guild! I don't have a clue on half the studd that guy talks about, and I am under the impression that if I fiddle with that gizmo I'll be the greatest badass DYI apprentice in the whole cemitery.

Re:I feel like an idiot

[Anonymous Coward]

Hrm let see there are all of 3 components in this simple setup all off the shelf a little math or just get the biggest ones you can find and your good add some of that ungodly big power wire scraps that your frind with the huge car sterio has and you have a working ups.

But realy a few diodes and fuses would be nice for general safty's sake ESPECIALY if your like me and have a battery farm with home made buss bar around (yes those nice solid copper grounding strips with predrilled holes work very well hit the junk yard for a lot of battery clips and you have a nice rail setup) Just remember cross the buss bar and you can ark weld two and craftsmen does take back a melted handle with a somewhat legible craftsman logo on it after it discharged 10 or 20 cranging lead acids.

If you cant manage to get something as straight forward as this please refrain from changing your own oil cooking dinner or anything much more intensive than walking.

Re:I feel like an idiot

[Anonymous Coward]

Well, it takes a certain amount of familiarity. So, if you don't understand his story, then rather don't try it. Although, if you do understand his story, then you probably did not need to read it...

Fixing APC Smart Rack UPS

[TibbonZero]

Does anyone know anything about fixing, or getting fixed a UPS that doesn't work that I got for cheap?

I can give more details if needed

Re:Fixing APC Smart Rack UPS

[delta407]

If you got it for cheap, used, its batteries are probably shot. Like most laptops, replacing the batteries on an older UPS would often be more expensive than simply replacing the UPS.

A lot of companies bought a UPS or two at more or less the same time (remember the dot-com days?) and these are about at the end of their operational life. So, if you see a cheap used UPS on ebay, it's probably worthless.

Re:Fixing APC Smart Rack UPS

[MrPoopyPants]

Do you have a local battery store? You don't have to buy the APC approved battery. Get a standard battery at a local store that matches the specs and your UPS should work. It'll probably cost like $20.00 US.

Good luck

Re:Fixing APC Smart Rack UPS

[plover]

The author cautions about taking an existing UPS and trying to add more, bigger or extra batteries. The power supply inside is built (cheaply) to deliver only the amount of current required to charge the battery it was designed for, and no more.

However, you can probably replace the battery in your UPS with a similar model for less than the cost of a new UPS. Either find the manual for your UPS, search for your UPS model on line, or open up your UPS and see if it has any labelling regarding the battery capacity, or (better) a "replace battery with XXXXXX model or equivalent." Find an equivalent on line (thanks, Google!)

Check with a battery store (most major metropolitan areas will have several.) It may be worth the drive, as batteries are heavy, cost much to ship, and can only be delivered via ground (slowly.) And if you're uncomfortable working with live circuits or very hazardous materials, they'll probably be able to replace it for you for a small fee.

Finally, PLEASE RECYCLE YOUR OLD BATTERY! In most states, it is illegal to dispose of any lead acid batteries in the garbage or in a landfill. They are filled with corrosive toxic sludge. Please be responsible.

Re:Fixing APC Smart Rack UPS

[TheOldFart]

Not so... That would be the case if you order the battery replacements straight from the manufacturer (usually very expensive as it is the case with APC). I just bought 4 big (1250VA) UPS and all batteries were dead. It cost me $17 per battery (standard sealed lead acid 12V 17A). After 8 of those I have four, just as new UPS systems for a total cost of less than $300.

Re:Fixing APC Smart Rack UPS

[slittle]

Any UPS that doesn't have user replacable, hot-swappable batteries is a piece of shit (IMO).

Most home/SOHO units seem to like the 7Ah SLA type, which are pretty cheap.

Re:Fixing APC Smart Rack UPS

[ncc74656]

If you got it for cheap, used, its batteries are probably shot. Like most laptops, replacing the batteries on an older UPS would often be more expensive than simply replacing the UPS.

UPS batteries tend not to be as expensive as notebook batteries...there aren't as many different varieties, so they tend to be somewhat standardized. I recently replaced the two 12V 7Ah batteries in a UPS at home. That UPS cost about $170 when I bought it. New batteries were about $40 for two. Given that the UPS is a 900VA unit that can keep a dual-P!!! server running for about half an hour, $40 isn't a bad deal to keep it running.

Re:Fixing APC Smart Rack UPS

[Agent Green]

Or, you can do what I did...and instead of paying $200 for an equivalent battery, you can spend that on a couple of Die Hard Deep-Cycle Marine batteries and 4-gauge cable hardware. ;)

This was a Smart UPS 1400 RM. The newer XL models actually have an expansion plug on the back which can support a few of these puppies. I'll get an XL model off of ebay someday...but the homegrown hack will have to work for now. ;)

Re:Fixing APC Smart Rack UPS

[AaronW]

I have repaired a couple of UPS. Every time it
just required that I replace the batteries.

I regularly see cheap =$20 UPS at the local Silicon Valley swaps where usually the only thing wrong is that they need new batteries.

I picked up a Tripplite Omnipro 1400VA UPS for $25 and a few months later picked up 5 batteries for $20. I also picked up a small Deltec UPS for $5 and a new battery for $12.

As for the Tripplite, it appeared totally dead when plugged in with the dead batteries that came with it.

Cheap UPS

[delta407]

Or, then again, instead of building one you could scour your local office supply stores and just might happen to get lucky. I got a "last year's model", 650 VA UPS, new but in a beat-up box in the clearance bin. It really looked like trash and subsequently was repeatedly marked down from well over $100 to $10.

Somehow, I get the nagging feeling that this pristine condition UPS (that I'm using right now) was worth more than $10 :-)

Re:Cheap UPS

[Simon Garlick]

My story:

A well-known power accessory company which shall, for obvious reasons, remain nameless* recently released a new model of their networked rackmount UPS, thereby necessitating a price reduction for the previous model. After some calculations by representatives of the nameless power accessory company*, it became evident that the exorbitant "official testing and certification" taxes charged by the state govt would, when the price reduction on existing stock was taken into account, mean that the company would barely break even on sales of the older, but just as fantastic, UPS units.

Outcome: the units got "misplaced".

Some quick emails and phonecalls went out, and guys-who-knew-guys-who-knew-guys made a series of surreptitious visits to the warehouse. Along with many others, I walked off with a direct-from-factory, unopened, 1400VA, DHCP-addressable, http-serving, rackmount UPS. Insane.

God bless bureaucracy!

*APCC

Re:Cheap UPS

[Qrlx]

Sooo...you transferred them to a secure storage location. :-)

Did you put them on ebay??

Re:Cheap UPS

[timeOday]

Just test it before you trust it. Rechargeable batteries degrade horribly with time, especially when setting on a shelf (or in a clearance bin).

Why convert DC to AC to DC?

[cyberformer]

A major part of the description on the site (and the cost of a "real" UPS) is how to convert the DC output of a UPS to the AC power required by most PCs.

Of course, PCs don't actually use AC power: there's a big box in the back that converts all the AC input back to DC. So why not save some money and bypass this, by running the PC straight off the battery (like a laptop)?

Re:Why convert DC to AC to DC?

[delta407]

Well, for one, your computer isn't simply running 12V -- you need 5V and in most cases 3V as well. (Possibly others.) Additionally, some components (AMD processors in particular) have very narrow operational ranges in terms of how much juice they get, and battery levels fluctuate.

Yes, you could work around this without going to AC, but it's easier and more flexible to just provide AC and let the power supply worry about the rest.

Re:Why convert DC to AC to DC?

[seanadams.com]

So why not save some money and bypass this, by running the PC straight off the battery (like a laptop)?

A latop doesn't run "straight off the battery". It has a switching power supply circuit which is not entirely unlike your desktop's AC->DC supply. Most of the stuff in there runs at 3.3V, whereas the battery is 18V or more. So you still need a power supply.

For desktop PCs, a 110V->5V supply is cheaper than a DC-DC supply.

Re:Why convert DC to AC to DC?

[ReverendRyan]

Another good reason is that you cant convert DC-DC and still maintain a decent amperage. The power supply in your computer uses multiple coils to attain the desired voltage+amperage levels.

Re:Why convert DC to AC to DC?

[Phosphor3k]

ATX Mobo connectors have to supply voltages of +12v, -12v, +5v, -5v and +3.3v. The molex connectors supply +5 and +12.

As a tip, if you need alot of voltage for a fan, you can splice the -12v going into the mobo, and put the fan between that line and a +5 or +12 to get a potential of 17v or 24v to run your fans off of. My Athlon almost runs at non-nuclear temps using this trick.

Re:Why convert DC to AC to DC?

[steveha]

I have, for years, wished for a DC input on the PC's power supply, and a standard for UPSes that would plug in to that DC input.

Taking DC, converting to AC so the PC power supply is happy, then the power supply converts to DC... it would be nice if it could just be DC all the way.

The problem is that your monitor, modem, etc. all expect AC power. It's easiest just to make a UPS that provides standard AC power, and plug everything in.

Someday, I think we will have "smart" plugs. Wall power outlets will not be live by default; they will only serve power when a proper coded request goes in over a smart plug. The device will be able to tell the wall outlet what kind of power it wants, and the outlet will be able to tell the device what kinds of power it can offer. Then little kids will stick butter knives into wall outlets and not get fried; PCs and monitors will ask for +5 and +12 volts DC and get it; and UPSes will be able to feed +5 and +12 volts DC to those PCs and monitors.

Actually, if you have the complicated smart power system I envision, there will probably be a UPS integral to the system. When your home loses power, the smart power system would broadcast a "power interrupted" signal and devices like your refrigerator and your laser printer will power themselves down; your PC will run for about 5 minutes and then power itself down (unless you are there and override it) and medical devices will run indefinitely. Maybe only the DC devices in your home will be on the UPS by default?

steveha

Re:Why convert DC to AC to DC?

[mentin]

Actually, unless you have some custom hardware, standard AC->DC adapter in PC only supplies 5V and 12V to motherboard - it is just standard. And motherboard itself provides lower voltage levels, suitable for particular CPU.

I also think that battery level fluctuate much less than the result of DC->AC->DC conversion of it. And you don't have to connect batteries directly to motherboard - you can use the same stabilizer that is used in PC's AC->DC adapter.

So I think avoiding DC->AC->DC layer can be a very good idea if you build custom hardware.
At least, you can spare couple of coolers and get quiter PC.

Re:Why convert DC to AC to DC?

[Oculus Habent]

The Power Supply in your computer may not mind square waveform because it's just making nice clean DC out of it, but I think the more sensitive components in your computer wouldn't like it so much.

Of course, you could go laptop auto-adapter style and have a clean DC-to-DC conversion.

Say, anyone feel like a UPS-in-a-case mod?

Re:Why convert DC to AC to DC?

[Anonymous Coward]

Although not "smart" by any definition, people using "alternative power" (wind, solar etc.) are already doing this to a certain extent. There are things like DC light bulbs, DC refrigerators and so on. Anything that probably SHOULD be running on DC rather than AC, is. You basically have DC-24V and AC-120V. These DC appliances have their own DC/DC converters etc., which is much more efficient than DC-AC-DC conversions that most standard electronics would require in an alternative power environment.

That said... Sun and many other manufacturers sell DC power servers, switches, routers etc. These are mainly for datacenters, where there are massive power/cost advantages to run DC instead of AC. Since a lot of us build our own computers and select power supplies independant of the case, perhaps some day we'll see standard DC power supplies for ATX cases? That would be cool. In the mean time, a DC power supply (power converter, I should say) seems to be next on my list of projects, along with this UPS.

Re:Why convert DC to AC to DC?

[petecarlson]

Someday, I think we will have "smart" plugs. Wall power outlets will not be live by default; they will only serve power when a proper coded request goes in over a smart plug

Before pluging in your new MSlamp, click here to agree to our EULA.

Re:Why convert DC to AC to DC?

[kfg]

Very simply because in most applications simply plugging things into the wall is easier and cheaper overall. This does end up with the typical home situation where every DC appliance in the house has its own AC/DC power supply.

The ideal situation would be where there was a "household" powersupply put in with the normal wiring harness, but we don't do it that way for a variety of reasons.

I *some* applications your idea is actually ideal though, those places off the grid, such as mountain cabins and marine installations.

To make it work you'll need a deep cycle battery, ("car" batteries are actually damaged by being allowed to run down), and a voltage regulator circuit, ( both the bits and instructions on how to make one available at Radio Shack). You'll also need to run a 12v LCD monitor. The whole rig will cost you about $100 US, and a couple hours of your time if you already know how to do it, and maybe 12 hours if you have to do the research.

Once upon a time this sort of electronics hack was just as popular a hobby passtime as software hacking is now and it's a quite doable project, but maybe a bit silly for straight home use.

KFG

Re:Why convert DC to AC to DC?

[ShawnD]

potential of 17v or 24v to run your fans off of.

And I bet your fans don't last very long, unless you buy 24V fans (not normally stocked at computer stores, but fairly common in electrons stores).

Re:Why convert DC to AC to DC?

[iamdrscience]

Well, for one, your computer isn't simply running 12V -- you need 5V and in most cases 3V as well. (Possibly others.) Additionally, some components (AMD processors in particular) have very narrow operational ranges in terms of how much juice they get, and battery levels fluctuate.

You can buy voltage regulator ICs for 5V (7408 IC I think?) and also I believe for 12V. I've only worked with the 5V ones, but they all work the same, they have three pins, one for voltage source, one for ground and one for the output voltage (5V, etc.) the input voltage on a 5V one can be something like anywhere between 7V and 15V and you get a perfect 5V out. These ICs are about a buck, plus without a whole lot of trouble you can build one yourself (if you wanted a tricky voltage like 3.3V or something).

Re:Why convert DC to AC to DC?

[Ig0r]

None of those ICs will be able to source enough current (15A for a cheap power supply) individually to economically replace the system's PS.

Re:Why convert DC to AC to DC?

[Fastball]

Even better would be cordless, plugless power. My apartment looks more like a heavily booby-trapped jungle from all of the tripwire power cords I've got strewn about.

Is it possible to transfer electrical power from a source to a device without a wire? If so, anybody know of any related work? I'd be interested to know.

I'm all about wireless. The more and sooner, the better.

Re:Why convert DC to AC to DC?

[Sanat]

7805 for +5V DC
7812 for +12V DC
7905 for -5V DC
7912 for -12V DC

pin 1 input voltage
pin 2 DC ground
pin 3 5 volts (or 12 volts) output voltage

Re:Why convert DC to AC to DC?

[mindstrm]

The reason for doing so is regulation. You would have to have a solid dc->dc supply inside the box in order to ensure everything worked well.

Your wall system sounds neat, but the problem arises that it is hard to regulate power on such large lines. You usually regulate DC, especially when dealing with low voltages in computer, as close to the destination as possible to avoid interference spiking the voltage.

In fact, to make it work, you'd need the power conversion circuitry at the wall plug.. otherwise you add in all kinds of resistance along the wiring as well.

Re:Why convert DC to AC to DC?

[Permission Denied]

s it possible to transfer electrical power from a source to a device without a wire?

Absolutely. When I was in college, my first-year physics professor had this interesting demonstration. He had a small light bulb stuck on the middle of a rod, and a radio. He would turn on the radio, stand at the other end of the auditorium and the bulb would light up if he held the rod horizontally, but it wouldn't light up if he held it vertically (the rod acted like a standard 1 dB antenna). I think his demonstration had something to do with polarization (not too big on physics), but the point is that it can be done.

Other people have probably already thought of it, so there's probably a reason it's not currently being used. One possible problem might be that in order to supply any decent amount of power, the watts you have to pump through the air will get dangerous. High-power radio waves can kill you: first, they'll make you sterile, then, after a while, you'll get a headache and a stomach ache. By the time you feel any pain, you're well on your way to death (at least this is what happens at the microwave end of the spectrum, I don't know what happens with higher frequency electromagnetic waves).

Re:Why convert DC to AC to DC?

[(outer-limits)]

I can see Thomas Edison rising out of his grave now, saying "See, I was right!".

Re:Why convert DC to AC to DC?

[tech_guru5182]

this would be easily feasable in an old at system, but we now have to deal with atx, where the ac power does not leave the power supply inside the case.

Re:Why convert DC to AC to DC?

[Permission Denied]

These are some very interesting ideas: on the other hand, after some thought, I realized I wouldn't want a house and appliances like this.

This violates KISS: with the current setup, about the only thing that can go wrong is that I trip a breaker or blow a fuse. I can then go to my box and flip the breaker or go to the hardware store and get a new fuse. With a complex system like you imagine, almost any problem would require a professional electrician to fix and expensive components to replace. Also, batteries don't last forever, so you now have a recurring maintenance cost if your UPS system is "on-line" ("on-line" is what the UPS people call systems where the input AC feeds the battery and the battery feeds the output and "off-line" systems are where the AC passes through except when there's a problem, in which case there's some very fine circuitry which very quickly switches to the battery - obviously marketing jargon, an engineer would have come up with more descriptive terms).

This is sort of like what happened with automobiles: a friend of mine used to have this '67 VW Beetle. I flipped through the Chilton's for that car, and the great thing is that you could understand ALL of the car and fix most things yourself. I have a 1999 Pontiac Grand Am, and I can do very little work on this car since I don't have expensive diagnosis equipment.

Very interesting ideas, but I certainly don't want to be one of the first to have such an experimental house: I'll stick to simple breakers and fuses for now. However, if your ideas are implemented on a wide-spread basis, I'll jump in: as much as I like the idea of tinkering with a '67 Beetle, I enjoy driving my Grand Am much more.

Re:Why convert DC to AC to DC?

[(outer-limits)]

What we actually need is a new generation power distribution system. The current one is over a century old. I would like to be able to have ultra low power gadgets, rechargeable, and can be connected to a low power dc power strip that runs around the whole length of the walls. Devices can be plugged into it anywhere. The only place were we would still need high power devices, such as heaters, etc, (tvs, computers, hi-fi etc, would all now be low power dc connected.), would still use AC.

Re:Why convert DC to AC to DC?

[steveha]

Your wall system sounds neat, but the problem arises that it is hard to regulate power on such large lines.

I don't know much about the practical details of electricity. I had sort of pictured several wires, one set with 110 Volts AC and one or more sets with DC, probably on smaller wires.

Would the hard-to-regulate problem go away if we had room-temperature superconducting wires?

to make it work, you'd need the power conversion circuitry at the wall plug

How bulky is the equipment needed to regulate DC and/or split multiple voltages off one DC line?

I assume this needs transformers, rectifiers, capacitors, and other bulky stuff that dissipates heat. Darn. I was hoping you could have everything in one box in the basement.

steveha

Re:Why convert DC to AC to DC?

[Gaccm]

as the other poster said, most fans can't do well beyond 15v if they are designed for 12v. Your gonna burn out your fans faster by the increased heat. I seriously suggest buying a high quality ($50) heatsink (if possible, 80mm) and put in a normal fan.

Do you have your comp on your desk? Mine is so loud i did the 7v trick (run the cpu fan at 7v [12v and 5v wires]) to make it quiet, only runs ~2C hotter too.

Re:Why convert DC to AC to DC?

[Anonymous Coward]

It's sad that onlyone person mentioned Tesla. :/

Do a search in Google, snag anything relative. I found some nice .ps schematics 2 yrs ago for instance...

Re:Why convert DC to AC to DC?

[Anonymous Coward]

Most of that amperage is going to things like your RAID setup, CDRW, DVD, etc. To power just the mobo (and video card, KB, mouse, sound card) those ICs should do the trick.
If not, I'm sure that using more than one in parallel for each required voltage (ie 2 ICs for the +5, 4 ICs for +12, etc) is another option.
Either way, I'd set up a seperate regulated circuit for each molex connector.
Also, doing it this way makes the original power supply obsolete. May as well remove it and hack in the battery and v.reg circuitry, along with a recharging circuit. Oh, another benefit of not going DC->AC->DC is the battery will hold a charge MUCH longer. No longer would you need to fight for 3+ power outlets at your next LAN party!!!

Re:Why convert DC to AC to DC?

[SmittyTheBold]

DC gets wonky when you run it long distances, which really isn't very far when you're talking about 12V.

That's a big reason the power grids all over the world use AC instead of DC.

Re:Why convert DC to AC to DC?

[jd_esguerra]

Another option is to convert from AC to DC to DC. Go from 110VAC or whatever to 24VDC and use a DC to DC ATX power supply (http://www.keypower.com/DC_power/DX-250H.htm) to power your PC. In the evernt of a power outage, switch from AC-(24VDC)-DC to just (24VDC)-DC. Don't know what you'd do about the monitor; If all that has to happen is a clean shutdown, you might not need a monitor. I'll be using a dc to dc atx supply like this to power a PC on a robot (no monitor)-- rather than the usual dc-ac-dc tricks. These thing are popular for use on boats/planes.

Re:Why convert DC to AC to DC?

[Anonymous Coward]

I used to work with high power microwave antennas in the Army and I managed to never fry anybody... I was told that if you got caught in the beam it felt like the sun just came out and was shining on your insides.

This, of course, was as it was cooking you like a hotdog in a microwave.

Those beams could power a hell of a lot of wireless equipment.

Re:Why convert DC to AC to DC?

[Anonymous Coward]

You are a complete piece of shit to compare dring a pontiac grand am to a beetle.

I drove the Pontiac for a week a moth ago, and it was the biggest piece of shit I have every driven. No accelleration, corners like its about to fall off the road, plasic spastic interior.

I hope you never have cool house

Re:Why convert DC to AC to DC?

[gora]

Until fairly recently Mozambique (South East of Africa) used to transmit power from the Hydro-Elec station through DC lines. The +ve and -ve lines were never less than 1Km apart for several reasons, and they did struggle maintaining reasonably stable voltages.

Re:Why convert DC to AC to DC?

[mpe]

The problem is that your monitor, modem, etc. all expect AC power. It's easiest just to make a UPS that provides standard AC power, and plug everything in.

Modems typically require something in the region of 12V DC. It is prefectly possible to build a monitor which will run from a 12V supply. The problem with "standard AC power" is that it isn't any kind of standard. Different voltages and frequences are used throughout the world. COmbined with even more different types of connectors.

Re:Why convert DC to AC to DC?

[Octorian]

Last I checked, telco systems had to run off DC due to regulations on line noise, or something like that.

Thus, you can easily buy Sun Netra rackmount servers with DC power supplies (or AC, whatever you want). They take 48VDC, and regulate it down to whatever the guts of the computer wants to use.

Re:Why convert DC to AC to DC?

[bluGill]

No, DC actually works better than AC for long distances. However the longer the distance the higher the needed voltage.

AC however has the advantage that you can change voltages cheaply and efficantly. DC is much harder to work with from that standpoint. This ability to change voltages is why AC is used. (There are several other reasion, induction moters and problems switching DC are others).

AC works poorly for long distances because the peaks travel. Power may go around the earth 7 times in a second, but AC will reverse 60 times (US) in that second. If you have generators all over the country, then eventially you will have a place where power from one generator is positive, while the other is negative, and that doesn't work very well.

Re:Why convert DC to AC to DC?

[dr_db]

Friend of mine was a radio tech in the armed forces. To get the class to pay attention, the instructor loudly said "If you make a mistake and get in the beam, the first thing that will happen is your testicles will explode"

Immediately have quiet and attentive students.

Re:Why convert DC to AC to DC?

[mla_anderson]

I don't know what computer you have, but in all of my computers the AC stops at the power supply and everything else inside the case runs off DC. This means that as long as the power supply is happy with the square wave the entire computer is happy with it. Most monitors will function just fine on a square wave as well.

I have seen a UPS power supply for sale somewhere, just can't remember the link right now. That concept has the problem of not being able to power the monitor--not much of a problem for a server, but for a workstation it's somewhat critical to be able to see what you're doing.

My sig is a SIG-552 (CS)

Re:Why convert DC to AC to DC?

[tzanger]

Linear regulators like the 78xx/79xx and LM317 and co. are all fine and dandy but you'll be whoring a lot of power out as heat. I'm also not sure that they have the regulation required to meet the various power quality specs that motherboards require. Go switchmode and get your efficiencies (and step responses) up.

Or, do what everyone in the telco business does and buy DC AT/ATX power supplies. -48VDC in, regular switchmode supply for all your motherboard needs. And no UPS required.

Re:Why convert DC to AC to DC?

[cgleba]

LOL. . .

For those of you who don't know, Edison had a big battle with Westinghouse whether homes should be powered by AC or DC. Edison envisioned small DC power plants on every street corner because AC was dangerous. Westinghouse envisioned a large, central power plant that drives high-voltage electricity long distances and more efficiently powers the most common electrical appliances of the time -- light bulbs and electric motors.

The battle got UGLY -- to the point that Edison invented the electric chair to prove that AC was dangerous!

Re:Why convert DC to AC to DC?

[Anonymous Coward]

NOT TRUE: A standart PC power supply IS a DC-DC converter, when the AC enter the PSU, it is rectified with a diode bridge, then filtered with a nice big capacitor, providing then a neat 300V DC (in Europe ;-)). There is a switching unit that "chop" this quite high voltage to pulses, pulses that are thrown in the transformer at a quite high frequency (+/- 30kHz). On the secondary side, you collect low voltage, high current pulses, rectify and filter them and you have your clean +5V.

The only things that should be modified to make this baby run off a car battery are the primary side of the transformer, less turns but ticker wires, and the chopper transistor, since the switching current is not the same, you must fit bigger (if not multiples) transistors on a bigger heat sink. Forget the fanless design :-)

Re:Why convert DC to AC to DC?

[Anonymous Coward]

The battle got UGLY -- to the point that Edison invented the electric chair to prove that AC was dangerous!

IIRC, he didn't invent the electric chair he merely pointed out the fact publically that all the electric chairs in use were run of off the Westinghouse AC generators.

Re:Why convert DC to AC to DC?

[Anonymous Coward]

What we actually need is a new generation power distribution system. The current one is over a century old. I would like to be able to have ultra low power gadgets, rechargeable, and can be connected to a low power dc power strip that runs around the whole length of the walls. Devices can be plugged into it anywhere. The only place were we would still need high power devices, such as heaters, etc, (tvs, computers, hi-fi etc, would all now be low power dc connected.), would still use AC.

The problem with low voltage being run around the house is voltage drop. The wires would have to be quite large (and therefore expensive) if run for any distance to reduce voltage drop, since if you lose a couple volts on a 12VDC line that can be significant where if you lose a couple volts on a 120V line (AC or DC) you normally wouldn't care. It's easier and cheaper to have the DC converters where they are needed, perhaps unfortunate but true as it leads to all those "wall warts" scattered about the house and collecting under computer desks.

Just because it is old doesn't mean its bad, "wrong" or outdated. After all we still use hammers and nails to affix one wooden board to another for a variety of structures, just because humans have been doing that for who knows how long doesn't mean its bad. It means it works quite well for its intended use, so well that we've been doing it for who knows how long.

Australian monopoly money

[Anonymous Coward]

I can substitute 110v for 220v easy enough, but can someone please be a karma whore and do a Google search to tell me how much $AUD1 is in a real man's currency?

Re:Australian monopoly money

[MaxVlast]

1.18 New Zealand Dollars =)

Re:Australian monopoly money

[Wild Wizard]

between 55c and 60c check the sign in the front window of your local bank they should have a list of exchange rates
or try a travel agent

Re:Australian monopoly money

[Anonymous Coward]

Rule of thumb

$US1 = $AU2

It's actually not quite that bad, but basically just half the $AU amount.

And what do you mean "real man's"? Your money is all green, and it all looks the same!

Re:Australian monopoly money

[andersbd]

A better way: Universal currency converter

Basically what I've got for my emergency radio

[Beryllium Sphere(tm)]

Coupla caveats:

Put a "battery isolator", or at least a power diode with a heat sink, between the power supply and the battery. And allow for the fact that it will drop .3 or .7 volts.

Don't even think about wet cells inside the house. Sulfuric acid belongs out of doors. There's a reason you're allowed to ship the Concorde battery without declaring it hazardous: it won't spill. Further, a non-sealed battery will release hydrogen while it's being recharged. Is your computer room free of all ignition sources?

Fred KC7YRN

(I've seen a commercial 500 VA unit for US$40)

Re:Basically what I've got for my emergency radio

[morcheeba]

I'll second the diode - it's essential!!

Some power supplies (even some fancy lab power supplies - I've seen people kill them this way) don't have a diode on their outputs, so if you turn off the supply (or, say, the power goes out), then the battery will attempt to put energy into the power supply. If the power supply isn't made for this, it could smoke and/or catch fire. A diode ensures that power only goes *into* the battery. Put the cathode end (with the band, "negative") towards the + side of the battery, with the anode (the other end of the diode) towards the + side of the power supply. Make sure that the diode can handle the current (most diodes drop ~0.7v, so dissappated power=I*E=Charging current * 0.7v)

Second, I'd be really cautious about putting power supplies in parallel to achieve more current. While this will usually work, the same problem exists that exists: power supplies don't always behave well when connected to another supply. With one diode isolating each power supply and current-limiting supplies, this should work safely, but the voltage regulation may be poor and the supplies may not share equaly - things not of great importance here. The general problem in paralleling output transistors is that, depending on the circuit, increased temperature can lower the resistance of the transistor, which causes more current to flow through it (relative to the other transistors in parallel), which causes more heat, etc... until it blows (or the current limiting of the supply kicks in).

For another project, I wonder about UPS modding. I've got a UPS that puts out the right amount of power, but the battery is kindof small. It seems that I could replace it with a higher capacity car or motorcycle battery of the same voltage.

Re:Basically what I've got for my emergency radio

[newerbob]

You mean you have a battery for your CB radio? (I see your CB callsign in your sig. Or are you a no-code Extra? It's really the same thing.)

Is CB radio really useful in an emergency? I thought it was dead, and all that remain are trucker and gangsert wannabees yelling at each other with overmodulated audio.

Re:Basically what I've got for my emergency radio

[Bartab]

CB doesn't have callsigns, it's "no code Technician" not Expert and it's not the same thing by a long shot.

As for usefulness, police still monitor the emergency CB channel, and a Tech or better ham license will give you access to phone connections that are usable to dial 911.

Cellphones are better.

Re:Basically what I've got for my emergency radio

[evilviper]

a non-sealed battery will release hydrogen while it's being recharged. Is your computer room free of all ignition sources?

No, but my car engine sure as hell isn't either!

Re:Basically what I've got for my emergency radio

[Anonymous Coward]

Yes, cellphones are more handy, provided that the infrastructure supporting them hasn't been hurt in some way... which makes them somewhat less desirable in an emergency situation.

Re:Basically what I've got for my emergency radio

[Anonymous Coward]

I know some police may monitor the CB channel 9, but I know that in college, a few times I had car troubles, and the Truckers were definitely more helpful than channel 9.

In fact, I never ever got responses from channel 9.

Re:Basically what I've got for my emergency radio

[CharlieO]

Be warned that the charger rate of any rechargable battery will vary according to the size, given that they use the same chemistry.

Now small batteries need lower currents. This means the charger is cheaper, as it is cheaper to regulate small currents.

If you hook up a battery that is bigger than the original you run the risk of:
1) Not getting your battery fully charged - and this will effect its output voltage and the cutoff voltage of the invert circuits in the UPS so you may end up with LESS run time - wierd or what?
2) You may overheat the charger - if it is a really small battery then it may be a really cheap charge that does very poor current regulation (if at all) so you new big battery sucks current - result very very hot UPS.

And don't, even though it isn't sensible, put a smaller battery in a UPS. It will most likely be charged at well over its normal current rating - this leads to venting of hydrogen in all lead acid batterys, no matter how fancy the technologies - yes even the vented ones (see my reply further up this chain.

Re:Do-it-yourself UPS

[rmohr02]

What's a separate-boxes do-it-yourself UPS rig good for, besides making you look all technical and competent? ...You can use a bank of truck batteries to power your PC for a week without mains, if you like.

I fail to see a practical use for this, but that's gotta be one of the coolest things I've ever heard of.

Re:Better than paying 100 bucks for a Blackout Bus

[TibbonZero]

Could someone please mod this down a bit? :)

No hard feeling zorg, just the third post thing..

Great solution...

[Anonymous Coward]

But now you have 3 big boxes under your desk, instead of 1

Australia runs 240 V, not 220

[Anonymous Coward]

did you even read the article?

Re:Better than paying 100 bucks for a Blackout Bus

[zorg50]

Yeah, I agree with you...I was in the mood for a bit of trolling.. :/

Mistook UPS for..

[Kelerain]

United Parcel Service. It was kind of a shock at first. "out of spare parts"..

&nbsp&nbsp&nbsp&nbsp&nbsp'Yeah Bob, I just happened to have a couple hundred large moving vans, some tracking gear, and a few spare employees out in the back yard, so I decided to start my own parcel service! Now if I could just find some boxes...'

&nbsp&nbsp&nbsp&nbsp&nbspAlthough the real article is kinda cool, its didn't hold a candle to my origional expectations. Foiled again...

Expanding batteries

[seanadams.com]

One of the main gripes I have about the offerings from APC et al is that only their expensive, high-current supplies have the connector for expanding the batteries. This is unfortunate for those of us who care more about running time than wattage rating.

The other thing that's irritating it that they rate these things in "VA" (watts?), when watt-hours would be a more useful to know.

Anyway, it turns out that it's not too difficult or expensive to jury rig your own UPS with extended run times. Pick up some 12AWG power cable, a couple of marine/RV deep-cycle batteries (don't waste your money on sealed or gell cell). Then take apart the UPS, and wire two of the 14V batteries in series with the internal 28V supply. Oh, and use a fuse. :)

For about $500 in all, I was able to build a UPS like this that could power six servers for over 24 hours.

Re:Expanding batteries

[El_Nofx]

When I did tech support for Gateway I got a guy who worked for APC, he had a UPS on his Fridge, his microwave, his TV, his stereo, and his pc but forgot to protect his phone line, Lightning struck by his house and took out his modem, along with his mobo. After he told me all that I laughed so hard he hung up, I wonder what ever happened to him, hehe

Re:Expanding batteries

[GigsVT]

Keep in mind the AC safety rating of 12 guage wire (for wiring houses) is 20 amps. Probably less for DC. If your UPS is more than a small one, better use 6 or 8 guage.

Also, running non-sealed batteries indoors can be dangerous. Putting them in a box outside and running wires in would be best. It also allows for more expansion, and solar charging systems. :)

Re:Expanding batteries

[tconnors]

Anyway, it turns out that it's not too difficult or expensive to jury rig your own UPS with extended run times. Pick up some 12AWG power cable, a couple of marine/RV deep-cycle batteries (don't waste your money on sealed or gell cell). Then take apart the UPS, and wire two of the 14V batteries in series with the internal 28V supply. Oh, and use a fuse. :)

For about $500 in all, I was able to build a UPS like this that could power six servers for over 24 hours.

I tried doing that, by plugging in two rather large 12 V batteries in series, but blew the UPS while testing, because it just wasn't expecting to be up for more than 15 minutes, so the transformer was seriously underrated and got very hot very quickly, before developing an open circuit. Because I couldn't be bothered re-winding the transformer, I just grabbed my 350VA inverter, whipped together a circuit that flipped a relay within 4 milliseconds of the mains failing (2 cycles @ 50Hz Australian), and using the 12V batteries in parallel. I haven't tested uptime from fully charged to empty yet, because I only just finished the charger circuit, but it seems to last for 5 hours of more. Oh, of course, because my stereo is "mission critical", I have it plugged in too :)

Re:Do-it-yourself UPS? It's been done.

[rmohr02]

Then you keep asking yourself "What can brown do for you?"

Energy drain.

[Renraku]

Where's your battery-power going to go when the mains fail? How is it going to be stopped from running back into the mains? Thats the same problem with smoke-detectors that plug into the wall and have a backup battery. When the power fails, the battery is pretty much instantly drained back into the main.

Re:Energy drain.

[MaxVlast]

Burly diodes?

Re:Energy drain.

[GigsVT]

A single diode is all you need to prevent that. As another poster pointed out, make sure the wattage of the diode is high enough, and also allow for voltage drop of the diode.

An alternative would be to have a relay operated off a wall wart that would stay energized while the wall power was on, and cut the charging system off when the wall power went off. Again, watch amp ratings.

The value of your data

[ObviousGuy]

Aside from corporate networks where constant uptime is absolutely necessary, why in the world would someone want to shell out for a power supply? I can understand the hack value in piecing together your own UPS, but it's all pretty much worthless in the end. Any catastrophe that could knock out power to your outlet is going to be big enough to ruin the UPS in the process.

Unless you live in Myanmar with its unpredictable power producing capabilities, this kind of expensive toy is useless. Even in Myanmar, though, you'd expect that you'd be accustomed to backing up every once in a while.

Re:The value of your data

[Anonymous Coward]

Any catastrophe that could knock out power to your outlet is going to be big enough to ruin the UPS in the process.

You mean like a lightning bolt hitting a power line? I don't know about you, but up in Massachusetts, we get power outages once in a while - especially during winter. My (APC) UPS has saved me more than once this last year.

Re:The value of your data

[Anonymous Coward]

"Any catastrophe that could knock out power to your outlet is going to be big enough to ruin the UPS in the process"

A tree limb knocking down a line blocks from me will not hurt my UPS to the best of my knowledge.

Re:The value of your data

[ObviousGuy]

I'm sorry you live in a third world neighborhood where the power lines are still above ground. Do the cows stampede when there's thunder?

Re:The value of your data

[delta407]

Any catastrophe that could knock out power to your outlet is going to be big enough to ruin the UPS in the process.

What about high winds knocking over power lines? Or too many laser printers on one circuit tripping the breaker? Neither of those (usually) toast a UPS. Circuit breakers and fuses generally prevent the average commercial quality UPS from dying.

UPS systems exist for a reason; to supply backup power for small hiccups, to protect from surges, or possibly to give power for just enough time for the generators to get online.

Re:The value of your data

[Anonymous Coward]

The USA is a third world country now?

Re:The value of your data

[GigsVT]

Any catastrophe that could knock out power to your outlet is going to be big enough to ruin the UPS in the process.

You must not have weather where you are or something. 98% or so of the people in the world live in areas where natural events knock out power at least once a year. (educated guess)

Re:The value of your data

[TheOnlyCoolTim]

"america is a third world country, and people don't recognise it...and i think that that's pretty god damn sad, that they don't recognise their own country as a third world, third rate, third class slum."

Godspeed You Black Emperor! - bbf3

Tim

Re:The value of your data

[Anonymous Coward]

You've obviously never traveled outside of the USA if you really believe that.

Take your rap shit out of here.

Re:The value of your data

[TheOnlyCoolTim]

I don't believe it, I just thought the quote applied.

In context the guy saying it is some sort of nutjob....

And Godspeed You Black Emperor! is about as far away from rap as you can get.

Tim

Re:The value of your data

[ObviousGuy]

I'm probably going to get modded down for this, but...

I'd agree that approximately 98% of people around the world (give or take a couple percentage points) experience weather. However, in many modern countries (perhaps yours excluded) power is generated using modern techniques that are impervious to all but the most severe weather, and the transmission lines are underground, making them impervious to all but the stupidest backhoe drivers.

This is not a flame, but perhaps you need to expand your worldview to include those areas outside your hick town.

Re:The value of your data

[Wild Wizard]

> and the transmission lines are underground

yea right do you have any idea how much that would cost in australia where the power lines go for 1000's of km's across a very large and sparsly populated country

Re:The value of your data

[Anonymous Coward]

Why oh why you ask? My apartment has a low amp rating breaker. Everone once in a while I'll forget, and run the washer, dryer, air conditioner and microwave at the same time, and POOF! There goes my data. Yes, I want one. Yes, I think I'll build one.

Re:The value of your data

[ObviousGuy]

do you have any idea how much that would cost in australia where the power lines go for 1000's of km's across a very large and sparsly populated country

No. Do you?

Re:The value of your data

[DanCo]

From what I know about power systems (everything I know about power systems, I learned from watching Nova...), underground systems get knocked out by lightning just as often as above ground systems. Granted, it will be a little harder for someone to take out a power line with their car when the line is underground...

Re:The value of your data

[Enigma2175]

Any catastrophe that could knock out power to your outlet is going to be big enough to ruin the UPS in the process. Unless you live in Myanmar with its unpredictable power producing capabilities, this kind of expensive toy is useless.

Since when is a "catastrophe" the only time the power goes out? Wind, rain, snow, tree branches and many other things can cause power outages. If you live in California, you may also get hit with rolling blackouts.

Most outages last only a few seconds. Instead of all my computers rebooting, they just continue running. Rarely does an outage last long enough for the computers to actually shut down, but when it does they shut down gracefully. No lost data, no waiting for filesystem checks, just pure computing enjoyment. I can't understand why anyone would not have backup power for their delicate equipment.

Re:The value of your data

[Anonymous Coward]

1,000 per meter. Underground is rather expensive and with the fact the power source is a few hundred km away - or further - underground.

Feel like ponying up the bucks?

Re:The value of your data

[Anonymous Coward]

Let's assume you mean that in Australian dollars. You're saying it costs one million Australian dollars to lay 1km of power lines?

Those contractors must be direct descendents of the criminals Britain originally brought over!

Re:The value of your data

[ObviousGuy]

Source, please.

Re:The value of your data

[Grail]

Are you serious? Why wasn't your comment moderated as a troll or flamebait?

If you use computers for anything more than just running screensavers, you really do need to have a UPS. Here are some things that have caused outages at my home or office:

1) Vandals who break the lock on the fusebox and flip the main switch
2) Lightning striking the nearest substation, resulting in a half-second outage as the substation's circuit breakers break then reset
3) Trees rubbing the powerlines, shorting them out, thus tripping the circuit breakers at the substation
4) Housemate doing dodgey things with power supplies, thus leading to blown fuse in the fuse box

These are not catastrophes.

Besides, the money for a decent UPS is (from my POV) worth it to prevent my computers spending the next day and a half being rebuilt (by me) after suffering major hard drive corruption. I keep backups in case my machines are stolen, I'd like to have a UPS to protect against power failure.

There's nothing quite as bad as being seconds away from that final epic battle in Baldur's Gate 2: Throne Of Bhaal, having spent two hours already, then having the power fail. Ouch.

Re:The value of your data

[CrayDrygu]

However, in many modern countries (perhaps yours excluded) power is generated using modern techniques that are impervious to all but the most severe weather, and the transmission lines are underground

Are you some kind of idiot or something? That's not a flame, that's a serious question.

You obviously have never been on the eastern side of the USA, where the power grids were built before anyone thought to put them underground, and since the cost to bury them would be prohibitive, the power companies don't bother.

However, even that isn't an excuse, as above ground power lines can even be seen in Seattle (evidence: 1, 2), Salem, Oregon (1, 2), and Los Angeles (1, 2).

(Note: Most of those links aren't direct evidence, however there would be no need to mention staying away from downed power lines if they're all buried.)

Re:The value of your data

[Anonymous Coward]

Go live in Northern Alaska for a year.

Re:The value of your data

[CantGetAUserName]

I live in Hockley, it's a small town close (7 miles approx) to Southend on the south coast of Britain. In the last two days there have been fifteen separate events that have required use of the battery. We haven't had any blackouts for a couple of months, which is about normal, but any one of the above will bugger my computer if it's running. I know because that's the reason I got a UPS. Since the 16th, by the way, 127 events that needed the battery (mainly voltage dropping out, down to 90 at one point) (BTW, UK has 230-240 main, not 110)

Realistically

[r_j_prahad]

I live where there are a lot of storms and blackouts. Most of us aren't concerned with an UPS when shit happens that takes out our power. We're looking for candles, culverts, and the closest basement. We're filling our bathtubs with water because when we lose power, our water company does too. We're throwing first aid supplies in the back of a 4WD truck, not fucking around on the Internet. We're searching for loved ones, not URLs. I don't care if my PC suffers an unrecoverable crash as much as I care that my children are OK.

Get a life, people.

Re:Realistically

[Gerrioholic99]

Well UPS's are useful in large corporations that can't lose anything at all, and it can help to keep the company network running while a generator heats up.. that way there is absolutely no down time.. But why would a big company need to build their own.. beats me. I agree with you that as far as PC's go, a UPS isn't really worth the extra effort or cash

Re:Realistically

[Anonymous Coward]

whoa! whoa!

obviously since you have no use for a UPS, all efforts are wasted.

really, get a life and stop preaching.

Re:Realistically

[Anonymous Coward]

Hey, you forgot the tags!

Re:Realistically

[Anonymous Coward]

Get a life, people.

Some of us have lived in countries where power outages are common and not necessarily caused by natural catastrophies.

Re:Realistically

[MaxVlast]

Cut back on the coffee, man.

Re:Realistically

[Nogami_Saeko]

Agreed - I have a reasonable UPS on my machine at work (out of my pocket) and my machine at home. Both will run the machine for anywhere from 10 minutes (home) to an hour (work).

I really don't care about running my machine when the power goes out, I just don't want it to fry, want to survive power bumps without losing my work, and let things auto-shutdown when the battery gets low.

Some guys doing construction near my office apparently hooked their arc welder into a common power panel, and the UPS was going nuts clicking on/off every few seconds... But nothing happened to my PC because of it. Other people had assorted lockups, etc.

Re:Realistically

[ArsonPerBuilding]

Some of us have lived in countries where power outages are common and not necessarily caused by natural catastrophies.

So you mean California?

Is it worth the trouble

[Gerrioholic99]

I want to know... just how reliable is it.. is it worth the extra few bucks you save. Isn't the whole point of a UPS reliability.. and for someone who has never done anything like build one.. is this method a reliable and safe alternative to saving a few extra bucks.. IMHO it is worth sacrificing a few extra bucks to make sure that you don't lose that precious data

too easy

[lingqi]

slashdot is supposed to be for geeks: i would like to see a DIY flywheel backup system; efficiency is on the order of 95-98% if you use magnetic bearings... there is an exellent IEEE article in the IEEE spectrum magazine a while back -- it's not online though; few links here: Flywheel energy storage Magnetic Bearing stuff

Re:too easy

[Anonymous Coward]

Here in Austin, TX, there's another company that specializes in that. See their web page.

Or Even Better ...

[Snoopy77]

You could substitute 110V to 240V for us Aussies.

And whoever modded the other guy down who pointed this out, grow a brain.

220V

[Anonymous Coward]

How the heck did 220V suddenly become Australian? :D. here i thought we used it over here in Europe too, just those wierd yanks that use 110v :)

Re:220V

[Anonymous Coward]

Shoot, my wall-voltage last summer was over 135....called the power-company and they adjusted the neighborhood transformer...of course, it's still over 125.

Re:220V

[Anonymous Coward]

>...just those wierd yanks that use 110v

I guess us Yanks should apologize for being first to come up with an electrical distribution system.
IEEE goes into this matter but I've always found it interesting that if Edison chose 120v, then why have 110v rated light bulbs? What's with the 10v difference?

Lacking some features

[BagOBones]

IMHO un attended shutdown is one of the best features of the higher end UPS systems.. It safely saves your work and turns the computer of in case of an extended outage.. also what kind of surge protection do you get from that getto unit? Remote battery status? I use a UPS to protect my self from bad wiring and surges.. Hooking up to a settup like that would just be to unstable IMHO.. To each thier own, I guess

Re:Lacking some features

[Wild Wizard]

the surge protection from this would be great due to the isolation of your pc from the main power via a battery

Re:Lacking some features

[BagOBones]

Looking at the picture I don't see any isolation. The charger and the inverter connect on the same contact on the battery.. So if there is a power spike on the charger is would pass directly to the inverter then possibly to your PC. Some sort of protector would need to be put between the battery and the inverter for there to be protection..

Re:Lacking some features

[Anonymous Coward]

you would need one of the battery's that have 4 terminals on them 2 + and 2 -

Re:Lacking some features

[BagOBones]

That might be one solution, but I would still feel better with some sort of control device between them.. Even with 4 terminals who is to say that the spike would not carry through the battery.. Comercial UPS units are built to inturpt spikes or to self distruct in the event of a spike that is to large to dissapate.. I would still rather cook the UPS than my system.. Then again the retail ones offer to replace your equipment if they fail to stop a surge.. This is still a cool project but not someing I think anyone should trust there main system to.. I suppose your could put a RETAIL surge protected power bar in place between the inverter and the PC that would give you a resonable level of safety..

Re:Lacking some features

[GigsVT]

All a surge protector that you get in a store is going to be is some MOVs (metal oxide varisistors). Since we are in a DIY mood, you could just buy some MOVs yourself and hook them up. Some spark gaps may also be in order, in case of something big surging, it will help to save the MOVs from a sustained blow.

I'm somewhat in agreement with you though. This isn't something that someone with no electronics experience should do, and think they have something that is exactly like a commercial unit.

MMMMMM, fried /.er's

[gricholson75]

Really, I love fried /.er's, with mashed taters and corn. mmmmmmmmmhh.

Although, the smell is hard to get rid of.

I Don't Know If I'd Want To

[dupper]

The Speed of Business has been estimated, by a group of eminent physicists and economists, as roughly equivalent to the Ludicrous Speed. Seeing as how I have restraining belts in my garage workshop, stopping for lunch might destroy my beautiful helmet, thus rendering me unnattractive to that nice Druish girl I'm holding captive. No, I'll leave UPS to the proffessionals.

Note to MOCs (Moderators On Crack): not offtopic, as comment is based on a rather uncreative allusion to what I originally thought was the story's topic after first reading its subject line, before reading the body.

UPS maintenance

[PD]

These do-it-yourself UPS thingies are going to require maintenance. Car batteries are designed to deliver about 3400 amps directly into the alternator of a car, only during the time that you turn the key. They they trickle charge very slowly off the engine mains.

By contrast, UPS batteries are designed to discharge at a slower rate, but charge very very quickly to be able to work if the power suddenly cuts out two or more times in a row.

The problem with using one battery where another is required is that a memory effect can develop. That slow discharge on a car battery can cause it to lose capacity and in as little as 6 months it'll be useless for any power failures over about 5 seconds.

How much does a car battery cost? about $50. But, you're going to need one every 6 months or so, making a home built UPS actually many times more expensive than one you buy at Comp USA.

I know it's counter-intuitive, but many things about batteries are.

Re:UPS maintenance

[Anonymous Coward]

Actually car batteries also act like capacitors when you car is running giving you better DC regulation then the almost AC your alternator puts out. They would probalby work fine in this situation, but given that they leak acid I wouldn't use them in doors.

Re:UPS maintenance

[Sponge!]

Valid point, but you can actually purchase VRLA (Valve Regulated Lead Acid) (sealed of course) batteries, on the cheap, which are the same damn thing that go into the APC UPSes.

Check out www.batteryworkspa.com for some more info, they seem to be on top of things, and have good pricing, and I know for a fact they have these type of batteries, because thats where I get mine for my UPS-en when I need new ones.

Cheers!

Re:UPS maintenance

[nochops]

You're wrong.

First of all, your battery doesn't send power to the alternator...the alternator sends power to the battery. Why in the world would an alternator need power? It takes some energy from the running engine, and turns it into electricity to recharge the battery, not the other way around.

Second of all, no car battery outputs 3400 amps continuously. A UPS needs continuous output. Do you have any idea how much power 3400 amps is? And besides, you're probably referring to CCA or cold cranking amps, which tells you nothing about how much output the battery can sustain. For reference, a battery for an 8 cylinder diesel engine needs only about 1000 CCA.

Go here http://www.uuhome.de/william.darden/ and learn all you want about car batteries.

Re:UPS maintenance

[Thornae]

The problem with using one battery where another is required is that a memory effect can develop.

The author of the article might take issue with that statement. He recently penned a rant about the whole memory effect issue for the magazine he works for, which unfortunately isn't on line. I did find this paragraph, though:

Nor, by the way, do I intend to in order to "maintain the pack?s capacity", because I do not subscribe to the myth of "memory effect". If you think your camera, laptop, cellular phone or cordless drill battery suffers from memory effect, you are wrong. Check out http://www.repairfaq.org/ELE/ F_NiCd_Memory.html and the full NiCd Battery Frequently Asked Questions file at http://www.repairfaq.org/ELE/F_NiCd_Battery.html before you flame me about this.

I don't know enough about it myself to comment, but I'd suspect that Dan would be willing to indulge in a heartily technical discussion were you to email him about it...

Re:UPS maintenance

[Anonymous Coward]

Actually, YOU are wrong TOO. Some battery current IS used.

Alternators require a small amount of electricity to make electricity...it's called field current. Crawl under your car sometime(or pop the hood, depending upon the model car you have) and look for two wires...one will be fat and probably red; that's the output and goes straight to the rest of the + side of the electrical system. You'll also see a smaller wire, generally it's blue...that is the field wire.

Alternators are just generators with electromagnets in place of real magnets(because electromagnets, for the same size, can produce FAR stronger magnetic fields.)

Depending upon the vehicle, the output of the alternator is actually controlled by varying the current through the field coil.

Oh...also...alternators produce AC which is converted to DC. Internally they have diode packs(they look like little buttons) which are arranged to give you DC from the AC.

Re:UPS maintenance

[Phork]

correct! this is what deep cycle batteries are meant for. You can buy them in auto shops uasualy, they use them for RVs and boats. They are designed to be used fo rlong periods of time, recharged, then used most of the way down again.

Re:UPS maintenance

[Compuser]

As a physicist I had to design a portable
experiment. Imagine an industrial table
full of physics equipment. It drew more power
than any desktop or small server but needed
to run for hours. We bought a single AGM sealed
valve regulated deep cycle battery for $80 and
it has worked well. It provided power continuosly
for more than 4 hrs and as far as we can tell
has not lost much capacity yet (i.e. after a few dozen fairly deep discharge cycles). It has also
worked for a couple of years now without a hickup.
So from personal experience, this scheme works
very well, but a quality setup will run you ~$300.
Look at boating and RV sites and newsgroups for
names of good battery manufacturers and compare
prices. We have nothing but good things to say
about Concorde's Chairman batteries.

Re:UPS maintenance

[bigberk]

The problem with using one battery where another is required is that a memory effect can develop

Has anyone built a home-made UPS yet that relies on a flywheel for temporary power delivery? Not as crazy it sounds! See this article from IEEE Spectrum. Not as crazy as it sounds!

Re:UPS maintenance

[Grail]

Lead Acid batteries are not Nickel-Cadmium batteries.

If you slowly drain a car battery, then slowly recharge it, you'll end up warping the lead plates. That's one reason car batteries die so quickly in winter - people leave the lights on and the battery gets totally discharged.

The charging/discharging of a lead acid battery affects the structure of the battery. During the charge/discharge cycle, the lead sulphide isn't being laid exactly where it was taken from. The thickness of the plates changes, and any heat works to warp the plates a little. Eventually plates will crumble, or warp enough that they're in contact with each other. Dead battery.

No, it's not "memory effect", since you can't remove the crystals by running high amperes through the battery. But it's still "dead battery" land.

Re:UPS maintenance

[Christopher Thomas]

Has anyone built a home-made UPS yet that relies on a flywheel for temporary power delivery? Not as crazy it sounds! See this article from IEEE Spectrum [scientecmatrix.com]. Not as crazy as it sounds!

I thought briefly about this, but 1) energy density *really* sucks compared to batteries unless you're buying a carbon-fiber flywheel for $lots, and 2) a catastrophic flywheel failure is even worse than a catastrophic battery failure. It takes surprisingly little energy to make a very effective bomb (it's the momentum that gets you).

Batteries are cheap; batteries work. Just get marine deep-discharge ones and be prepared to handle catastrophic failures down the road (batteries outdoors, and limestone gravel is your friend).

Re:UPS maintenance

[nels_tomlinson]

Car batteries are designed to deliver about 3400 amps directly into the alternator of a car, only during the time that you turn the key.

Whoops, a couple of boo-boos here. That would be 300 to 400 amps into the starting motor. The glow plugs will have cold current of around 400 amps for a little 4-jug diesel, but that falls off to 40+ after a few seconds, as they warm up.

I agree with most of your information about starting and deep cycle batteries.

Re:UPS maintenance

[ndege]

Car batteries are designed to deliver about 3400 amps directly into the alternator of a car, only during the time that you turn the key.

<BIG rant>
Man, you have no freaking idea what you are talking about! How in the world did this get modded up to a score of 4!? Just fyi, I thought it was a starter that started the engine. AND, where did the 3400 amps come from!? This should have: (Score:4 Funny)

AND, a car battery doesn't develop "memory"...that is NI-Cad cells. I just wish all the supid little jerks that /. seems to have aquired over the past few years would disappear. BLARR

(I remember when /. was run over an ISDN. Times have indeed changed.)
</BIG rant>

Re:UPS maintenance

[mpe]

Alternators are just generators with electromagnets in place of real magnets(because electromagnets, for the same size, can produce FAR stronger magnetic fields.)

Most generators use electromagnets. Some have a small permenent magnet generator on the same shaft, powering the field coils.

Depending upon the vehicle, the output of the alternator is actually controlled by varying the current through the field coil.

Or by using a voltage regulator. Sicne the voltage needs to be kept constant, regardless of the engine RPM.

Oh...also...alternators produce AC which is converted to DC. Internally they have diode packs(they look like little buttons) which are arranged to give you DC from the AC.

An AC generator is easier and cheaper to build than a dynamo.

Re:UPS maintenance

[mla_anderson]

A marine style battery may have better performance for a UPS, they're usually designed for slower discharge rates.

The guy sounds interesting.

[gooberguy]

(Note - driving around the city with a passenger who's pointing a 240 volt disco strobe at unsuspecting pedestrians is neither condoned, nor encouraged, by the author. And even though it makes rain look really cool, please do not stand in the rain holding the strobe.)

It looks like he's tried this before. I wonder if he'll have an article on how to take apart your UPS and use it to scare pedestrians with a strobe.

D/\ Gooberguy

Home brewed UPS

[ClimberTech]

My friend once made a UPS out of some furbies and a big-ass fishtank... it was sort of cool, although it didn't really work, at all. But it was cool, ie: when we cut the power, one of the furbies blew up, and the water started bubbling... but the computer still shut off, o well.

Re:Home brewed UPS

[mikefoley]

I'd highly reccomend, if you are in the Boston area, and you like Furbies, to check out the Furby Wall at the DeCordova Museum in Lincoln, MA. Furby Wall

Australian Voltage

[Anonymous Coward]

Isn't Australian mains Voltage 240v not 220v

Re:Australian Voltage

[Anonymous Coward]

ACTUALLY is NOT 240 vac at all - it's in between 227 and 234 volts - depending on loads/power factors etc - I'm reading my DVM display now in Sydney and its 229 ~a/c...

Re:Realistically, Stupid HTML tags

[r_j_prahad]

Good of you to remember to include the new [asshole] and [/asshole] tags with your post as well.

Asshole.

speaking of conversion...

[trb]

$1.00 AUD = $.56 USD = €.60 EUR

Re:speaking of conversion...

[e-gold]

No, you reversed USD and AUD here.

http://www.xe.com/ucc/ is a converter.
JMR

Re:speaking of conversion...

[trb]

No, I had it correctly above. An Ozzie dollar is worth about half a US buck.

Re:speaking of conversion...

[e-gold]

I'm sorry, you're right, my bad, I had them reversed/confused.

My pals tell of great deals there lately, apparently exchange rates work well for US tourists there at the moment.
JMR

The Remains

[peterdaly]

Be careful with this stuff. Batteries can be nasty. At my previous job we had a "switch room" which housed out 50,000kva (yes "K"va) UPS. On the wall across from it were huge "grab the handle and yank" circuit breakers...which were covered in battery acid from the previous UPS.

Now this wasn't your home little ups box, this thing would blend in with three refrigerators side by side, and would run a 500 person electronics factory, and 500 person office (PC's at least) for 8+ hours. That was a kickass battery box.

Just remember, UPS's can go "BOOM" and I wouldn't want to try my hand at making my own and seeing it for myself. Some things are better left to APC and crue.

-Pete

Re:The Remains

[markmoss]

Also, anytime you've got a heavy battery, remember that when there's a short, the battery is a source of almost infinite DC current. At high DC currents, circuit breakers may weld shut when they ought to open, and if that's your only protection, your battery will pour energy into the wires and short until something burns away. It's a real fire hazard.

For proper protection where large batteries are involved, use fuses - best are those cylinders bigger than your thumb, like they used for the mains in houses 50 years ago, but the 1-1/4 by 1/4 inch glass fuses are apparently good enough for a car battery.

If you're looking for exandability...

[Corgha]

What's a separate-boxes do-it-yourself UPS rig good for, besides making you look all technical and competent?

Well, it lets you have monstrous battery capacity, if you like.

Why not buy the power supply and inverter in the same box, like this one, which sells for around USD$235.

Maybe it's a bit more expensive, but it can deliver 500 W (1000 W) peak, instead of 210 W (there are larger models available as well, up to 3600 W), you can use all the car batteries you want, and you may run less risk of electrocuting yourself.

Re:If you're looking for exandability...

[Anonymous Coward]

AFAI can tell, the only problem with TrippLite
stuff is price.

Re:If you're looking for exandability...

[Anonymous Coward]

I have an extra Tripplite APS1024 hooked up to my refrigerator (lock rotor current is only 39.8 amps). The two problems with the APS models are 1) the somewhat noisy fan runs constantly even when the inverter is off sucking up dust and 2) the 20+% harmonic distortion when the inverter is running. My Oneac line conditioners downstream help clean that up and I have a number of Sola ferroresonant line conditioner elsewhere which regulate and condition *exceedingly* well, with a pure 120V sine wave output even for a square wave 100V input (from my cheapo 7200W Generac generator). Ferroresonants are inefficient and noisy, and they don't work with motors high amperage when starting. If you buy Tripplite APS models get some air conditioner filters and cover the fan otherwise you'll end up with dust on its innards and it's a pain to open the case.

Frankly, I'd buy an APC SmartUps "XL" model instead (I use 1000XL and 2200XL models) which allow you to run the inverter for 6+ hours if you have enough battery power, and you can supply your own batteries too (either by crimping your own connectors or buying the Anderson power connectors that APC uses from a solar supply place like www.solar-electric.com. APC also have AP9606 ethernet expansion cards as well as emergency power off, redundant switches (2 separate UPS's feed your load switched by a relay when one goes) and other nifty expansion options.

Definitely use deep-cycle batteries -- golf cart (6V though), fork lift, or marine batteries are good, but solar cell batteries are really the way to go IFF you water them and maintain them. US folks should check out Costco, West Marine, even Sears for cheap deep-cycle batteries. Some cities have a Batteries Plus store, although their prices aren't very good. The one near me has Tripplite APS models though.

the Tripplite APS1024 wants 2/0 AWG wire for the batteries. If you haven't worked with that before, it's not cheap and it hardly bends. Welding cable at that gauge is more flexible but not US code-compliant (if that matters to you). And please please use a class T fuse too; you're dealing with some hefty amperage. Again, check out the solar supply dealers.

I do like the Tripplite APS ability to handle different battery chemistries: AGM, SLA, etc. and its ability to change the threshold where the inverter kicks in. That alone gives me 2+ days of run time on the frige.

If you want to graduate from Tripplite and APC check out Exeltech and Trace sine wave inverters, designed to power your whole house and loved by the Solar crowd. See Home Power magazine at www.homepower.com for lots of inverter info and reviews. www.nooutage.com has inverters and lots of other power stuff.

And yes, I live in California and this is my first /. posting.

obTrivia: while Tripplite isn't exactly known for their UPS equipment their Isotel Ultra surge protectors are better than anything else I've found for the money...

Good luck!

Re:Realistically, Stupid HTML tags

[Anonymous Coward]

I don't get it. Are you saying that I'm an asshole for calling the parent poster a whiner or that the parent poster is an asshole whiner?

Comment removed

[account_deleted]

Comment removed based on user account deletion

What a lame article

[frovingslosh]

This is hardly building a UPS, it's more of taking several expensive items (inverter, power supply and large battery) and hooking them together. Considering my $120 900 VA runs my power hog AMD system(including 3 hard drives and 3 CD/DVD drives), my 21 inch HP monitor and a hand full of other things (including the DSL modem and the d-link) at about 41% load, I'm a lot further ahead than trying this expensive hack. And if I need more power for additional hardware I can always add another (less expensive) UPS and still be way ahead, if I thought I needed longer backup times I could use the same large capacity battery the article uses, mount it outside my UPS, and I would still be way ahead. I'm all for build it yourself when that will save you cash and/or get you something better, but this hack just seems an expensive way to kluge together a UPS when you can buy better stuff for less cash.

Comment removed

[account_deleted]

Comment removed based on user account deletion

why australia?

[tahpot]

Why on the front page mention converting to Australian voltage? Why not english or something? I'm Australian, but what's so special about us.... /. surelly doesn't have the much of an Aussie representation does it?

Re:why australia?

[Wild Wizard]

actually its for the benifit of the large american audience
dansdata is an australian website and thus the article talks in terms of 240V (NB to idiot editor its not 220V)

Re:why australia?

[Anonymous Coward]

I beleive that was refering to converting from rather than to it. (the article is australian)

Re:why australia?

[lostchicken]

It's the other way around.

The article is about building a 220VAC/50Hz device. It converting from Aussie voltage.

Re:why australia?

[Anonymous Coward]

Did you even bother to read the article?

All units of measure in the article are Australian. The author makes mention of an Australian supplier. Perhaps the author is Australian? That would explain the conversion between AU and US.

Re:why australia?

[Zeddicus_Z]

The Dans Data article was originally written by Dan for our magazine, Atomic Maximum Power Computing.

As we're an Australian mag with a (mostly - we sell in New Zealand, Singapore and a few other places) Australian audience, its setup for 240V.

The UPS D-I-Y article appeared in AtomicMPC Issue 13 (latest issue is 18)

Re:why australia?

[Sanat]

When I worked in OZ back in the 70's the voltage varied by locations. Somplaces it was 240V AC and other places it was as high as 270V AC.

Did they standardize the voltages?

Well, are the train tracks the same gauge now?
Going into some territories they had to change the carriage wheels on the cars because the tracks were different widths

Old man needs an update!!

Re:why australia?

[Anonymous Coward]

a) Voltages
The voltage tolerances have been tightened, I can not remember what the mean value should be but the max and min is now within the European limits despite having a higher mean value.

b) The original voltage in the 70's was 250V, dropped to 240V in the late 80s.

c) Train tracks in rural areas are probably different gauges however the main inter-capital city lines are standard gauge.

Re:Do-it-yourself UPS? It's been done.

[willybur]

Brown says, "I want some more pie... *chuckle* Brown didn't say that."

Nonspillable batteries...

[Anonymous Coward]

They are hazardous and unshippable on a carrier not rated for hazardous shipment (in the US) unless they are for an electric wheelchair, and the wheelchair user is also being transported.
So suck it.

http://auction.apc.com/

[MattRog]

Or, you could visit:
http://auction.apc.com/

And get refurbished, and sometimes brand-new, warranteed APC power units for pennies on the dollar.

Two years ago I purchased two 420VA refurbished backups for around $50 each. They're currently protecting my three boxen, one of which I'm on now, and have been flawlessly through brown-outs, sags, surges, etc.

Typically the refurb'd units are from companies who have agreements with APC to buy many UPSs and return them when the batteries run out. Why? Customers used to return UPSs marked as 'defective' when in fact it was simply a dead battery. So, they tape over the battery bay and simply have the customers return the units with dead batteries and pick up a new one. They replace the battery and sell the ok unit again as refurbished.

Re:http://auction.apc.com/

[SONET]

I have purchased three rack-mount UPS units this way and I have been very happy with them. Now that everyone on slashdot knows, the prices will probably skyrocket. Oh well, it was good while it lasted! :)

--SONET

Re:http://auction.apc.com/

[gerardrj]

I can't get to the actual article due to it being /.ed. but from the converstation here I can assume that this is what APS would call a CPS.

At APS, a USP has a switch in it that causes the inverter to discharge the batteries and power your equipment when line current is lost.

This homebrew device seems to continually charge the batteries, and continually run the inverter from the batteries. (again, this is an assumption from the comments I've read here about the parts required).

The advantages of the homebrew are several:
1. no switchover time on line current failure
2. no switchover mechanism to fail and cause system downtime
3. provides for power conditioning
4. true spike protection
5. isolates systems from the line

It may seem unlikely, but it does happen that the solenoid/switch in a standby UPS does fail. Mechanical things jam, corrode, get dirty and such.
A true UPS eliminates the mechanichal switchover and associated risk.

This is so cool!

[Anonymous Coward]

I don't know what's better: the chance to hand out a few Darwin awards to people with no business around high-voltage, or the chance to laugh at someone who's trusted their data integrity to something they built using a car battery...

Brought to you by the good people at Folgers Crystal Meth Labs

Be careful with automotive batteries!

[llzackll]

Ordinary automotive batteries, like those used for cars, produce gases while charging, which can ignite and cause an explosion. Marine deep cycle batteries do too, but to a lesser extent.

I would be sure to keep them in a well ventilated area.

Re:Do-it-yourself UPS? It's been done.

[writermike]

Stupid S-N-L joke.

"Are you enjoying yourself?"
"Yeah! GO BROWN!"
"Oh? Do you go to Brown University?"
"No, I work for UPS."

I think I just lost some karma. :-(

Only problem

[Chacham]

Only problem with this UPS thing, is that I'd have to shutdown my computer to put it in! And lose my uptime, no way!

Besides, I don't use electricity anyway. It's all coming from monopolistic power companies that don't opensource their generators. My computer runs completely on GNUicity (power is generated everytime RMS blows a fuse). I guess that makes my system GNU/GNU/Linux. Or would that be GNU/Linux/GNU?

Re:Only problem

[Anonymous Coward]

Sheesh! Offtopic? Overrated maybe, but off-topic?

I love this guy

[nutbar]

A bench power supply is also a generally useful thing. I use this supply all the time when I'm building and testing things, or when I just feel like setting fire to a pencil.

I bet he used to set fire to ants with magnifying glasses too. Not that I'd ever do anything like that. No-sireee. Stop looking at me!

Re:I love this guy

[BakaMark]

A "acquaintance" of mine used to light up pencil leads that were used in the push type pencils. Of course you could not directly look at the result, the bright white light was probably be enough to blind you.

Re:I love this guy

[Anonymous Coward]

That is the basis of an arc lamp,

take 2 carbon rods, connect power... BRIGHT light!

from what i remember these are what they used to use to light movie projectors, and If memory serves me right the new HID headlights that every expensive car has, is just an arc lamp too, different design and luminessence

try taking 2 pencils to a stripped power cord and see the results... then do the same with 1 dill pickle and the power cord

You mean "Exploding batteries"

[plover]

I hope those batteries are properly ventilated, keeping all the generated hydrogen away from ignition sources such as monitor switches, light switches, etc. (Of course, you wouldn't have that particular hazard with sealed or gel cell batteries, but you didn't "waste" your money that way.)

I also hope that they're on a concrete slab or on a floor over a beam designed to hold up the unusual amount of weight. If it's just a wooden joist construction room on an interior wall, you may find your floor sagging in a year or two as the nails slowly release.

The other thing is that your UPS may run fine until a deep discharge or two, and then blow out the charger because you're drawing more current than the power supply was designed to deliver.

Re:You mean "Exploding batteries"

[seanadams.com]

I hope those batteries are properly ventilated

Did I mention there were quite a few servers? This room was very well ventilated, with a large fan pointing outdoors on one side of the room, and an intake vent on the other side of the room.

keeping all the generated hydrogen

UPS supplies use a slow trickle charge, so the hydrogen from the electrolysis is produced at an incredibly slow rate. I might be worried if I had banks of hundreds of batteries in a sealed undergruond vault... but let's be reasonable here!


I also hope that they're on a concrete slab or on a floor over a beam designed to hold up the unusual amount of weight.


Yep, these sat on the bottom shelves of heavy duty racks, which were bolted 6" into the concrete.

your UPS may run fine until a deep discharge or two, and then blow out the charger because you're drawing more current than the power supply was designed to deliver.

Like I said, this was just to get more run-time out of the UPS. I wasn't running it anywhere near to it's current capacity. I did a test run and monitored it for overheating before I put it into production use.

Don't be so prophylactic. Some of us know what we're doing!

Re:The Remains ( EE rules )

[Anonymous Coward]

The forgotten skill called Electrical Engineering ... Alas there all these computer geeks who make a motherboard with SMPS unit just next to the PC !!

See, these electoronics/Computer engineers are not really engineers--they probably be called at most poet or writers ...

REAL men would use THIS

[Anonymous Coward]

http://triggur.org/silo/env.html

We had a diesel generator sitting outside where I was working. Not that big but still.

When are the fuel cells coming?

Batteries ok

[TibbonZero]

Actually, the batteries are ok, I have tested them with a multimeter, and they seem ok

Re:Batteries ok

[Anonymous Coward]

that just shows you there's voltage, doesn't show you the current capacity and run time of the battery, which is the problem

kinda like those battery testers from Radio Scrap. Useless, even if they say the battery is good

Re:Batteries ok

[_Wrath_]

Beyond not knowing the current capacity.. or the amp-hours.. your multimeter is reading the surface voltage; the battery needs to be under load to know whether it actually holds charge or not.

Be prepared

[Anonymous Coward]

I live in the midwest United States. The only life-threatening storm around here is an occasional tornado. When the power goes out, it's usually because lightening took out a substation, or ice built up on a line and broke it.

When the power goes out around here, I do not throw first aid supplies in the back of a 4WD truck. That would be stupid. I stay inside where it is warm and cozy. Where I have food and water prepared ahead of time. I grab my flashlight (right by my computer), head off to the second shelf in the pantry, and grab some candles and matches.

Around here, instead of cutting taxes, we make sure the Public Utilities Commission has a backup generator. We put our water reservoirs on a hill, so that, should the backup generator fail, the entire city will continue to have running water for several days (that's the benefit of living in a valley).

Oh, and if I need to go someplace, I keep a first aid kit in my car all the time.

It would sure be nice, if I could sit down in front of the TV and find out why the power went out. Unfortunately, I do not have a UPS hooked up to the TV. Instead, I have to listen to RIAA sponsored music on my walkman, and wait for a weather report.

Atomic Magazine

[Anonymous Coward]

This guy writes for atomic magazine. They printed this article a few months ago.
If you can, check out the mag, its pretty good. The writers are nutcases but they really know their shit.

KABOOM!

[Nightwraith]

One of the major components of a QUALITY UPS is the surge protection provided in them. APC even has a warranty that will cover the cost of your fried equipment if your box gets fried while connected to their UPS.

If that contraption was struck by lightning (I've seen comps get hit) the surge would go stright through the DC supply and the BIG lead-acid battery would then become a GIANT burning ball of hydrogen and concentrated sulfuric acid.

I don't know about you but I have a few things in my "lab" that I don't want eaten by acid (not the least of which, ME!).

Problems with this

[Anonymous Coward]

1) The inverter will generate quite a bit of noise and heat.
2) Unless it's a really good inverter, it will not survive very long at 100% up time.
3) At 85% efficiency from the inverter, and far less from the linear power supply, this guy is paying for twice the electricity he needs to run his computer.
4) With no charge controller, he's going to ruin the battery soon. Worst case is a hydrogen explosion that kills him and his neighbors.

been there done that

[Anonymous Coward]

A few years ago, the Solar Car team at MTU (www.sos.mtu.edu/solar) had to do the same thing while at a race. We were running a data collection system and the power kept failing. We just used some of the old batteries from the car, hooked up a car charger and a small inverter from best buy. It was pretty kicking, and worked very well, when all other teams were cursing the power supply in the pits, we were sitting high on life

-Matt

Re:been there done that

[Anonymous Coward]

sorry... www.sos.mtu.edu/solarcar

-Matt

This is dumb and dangerous.

[newerbob]

I would not recommend doing this. Batteries are dangerous and can overhead or explode.

Also the cost for these components is *much* higher than a $59 APS UPS.

However, if you wanted to roll your own you would ditch the inverter and simply regulate the gel-cel down to the +12, +5, +3.3, +2.2, etc that your computer needs, and use a DC-DC converter chip to get the -12 and -5volts.

That's much more efficient and somewhat safer.

You wouldn't want a person without a CS degree writing software; we shouldn't have folks without EE degrees designing power supplies.

Re:This is dumb and dangerous.

[nd]

You wouldn't want a person without a CS degree writing software; we shouldn't have folks without EE degrees designing power supplies.

That's a pretty ignorant attitude. Plenty of people professionally write software without a CS degree (either they have some unrelated degree, or no degree at all). Do you think everyone developing the Linux kernel has a CS degree? Not even close. The fact is, programming isn't all that uncommon of a hobby, and people can get started at surprisingly young ages. It doesn't take long for them to get to the point where they're qualified to write good software if they do things right.

The statement is more true for "non-EEs shouldn't be designing power supplies", but still false.

Re:This is dumb and dangerous.

[Anonymous Coward]

Yeah right - designing a PC PSU is not as simple as slapping together a few Maxim ICs though...

Re:This is dumb and dangerous.

[gerardrj]

Edison shouldn't have built the first power station without a degree in EE.

The Wright Brothers shouldn't have built an airplane without a degree in airframe design or aerodynamics.

Denis Papin shouldn't have built the first steam engine without a degree in thermodynamics.

Most "cool" stuff was developed/invented by the crazy people without a degree in a relevent field. If you understand what you're working with and exersise som sound judgement you can do anything.

Re:This is dumb and dangerous.

[Anonymous Coward]

No, this is just dumb. STFU

Re:This is dumb and dangerous.

[Anonymous Coward]

You wouldn't want a person without a CS degree writing software

Fuck you, pal. Just because you're MSCE doesn't give you any right to make cracks like that. Hey, I've got an idea- How'sabout you pay for everyone who programs and has NOT got a CS degree to go out and get one?

What's that? You don't want to?

Well gee, in that case, bite me.

You open your mouth and let your lips flap in the breeze, meanwhile your foot gets jammed so solidly into it that you'll have to clip your toenails rectally.

-Sincerely, 3/4 or more of the people who make the Internet run.

Re:This is dumb and dangerous.

[jd_esguerra]

I agree that regulating dc to dc would work fine. However, moving from AC-DC operation to DC-DC operation in this manner would require switching from the normal AC at/atx power supply to your DC regulation circuit. This would probably happen inside the pc case, between the pwr supply and the motherboard. It's more convenient (maybe not elegant or adventurous) to create/feed AC to the pc's power supply than to splice into the cables going to the motherboard-- all the hardware hacking and stuff remains external to the PC.

Re:This is dumb and dangerous.

[newerbob]

HA HA HA HA HA HA! Just because you're MSCE

An "MSCE" is *NOT* a college degree. It's a certificate meaning you passed a test. And they're worth little. Maybe you give the nod to the guy/gal that has one if you need to hire some kid to crawl around on the floor hooking up PCs, but that's it.

Re:This is dumb and dangerous.

[Anonymous Coward]

*I* know they're worth crap. In fact, I'd likely pass over someone who's got one (for reasons of their current mindset, and likely lack of true imagination - think back to QBASIC.. ;). Problem is that many more places than ought to will take MSCE as though it were a real degree. So my statement stands, but I do acknowledge your statement as true.

110 Volts..

[Anonymous Coward]

..is for wimps.

SUN.COM DEFACED

[Anonymous Coward]

sun.com was just defaced! cracked into by some guy who called himself the fluffy bunny! huge news!

Old Old Old Old

[TheDarkRogue]

Back in the day I use to have an account on a BBS that did this exact thing. The sysop then got others to do this too.

On another note, one of the nice things about this is the ability to expand the source of the 12v in. For instance, a small array of solar cells wired together and into the battery taking the load off of the house current/AC->DC thingy during some days. When we did the math for it, it paid for it's self in about 4 month of sunlight every day, or about a year in real life. 12v is a nice little voltage to work with when it comes to this and alternitive energy sources. Hell, wire a nice little 12v DC generator to an exercise bike for when your bored. Get a work out and save on your electric bill. Also, if you want to go real insane/creative, suck off of the telephone lines when not in use, they got something comming through them i'm sure. It's alot easier to get 12volts then it is 110ac.

110 vs 220

[Anne_Nonymous]

>> Of course you can mentally substitute U.S. 110 volts for Australian 220 volts wherever necessary...

Holy S#!t! And I thought the Canadian exchange rate was bad!

Re:110 vs 220

[bollocks]

Don't laugh the exchange rate for the AU$ has been around the 50c US for quite a while.

I still remember when it was 1-1

Change of name

[SimplexO]

I heard to avoid confusion with 'brown', they were thinking of changing "Uninterruptible Power Supply", to "Power Management System".

Get it? :P

Wireless power?

[steveha]

You can beam power around as microwaves or a laser beam or something, but the equipment to collect the power and convert it will be large and bulky. And unless you want to turn your apartment into a large microwave oven with you inside it, you would need some kind of complicated aiming system to make sure the power only goes where you want it.

Simpler would be to have your gadgets run on battery power, with charging cradles.

If you imagine ultra-low-power technology combined with ultra-high-density batteries, you would have gadgets that don't need charging often and have no power leads. Then just have robots run around in the middle of the night, charging them while you sleep.

:-)

steveha

Re:The Remains ( EE rules )

[Anonymous Coward]

Well it's obvious you're neither a poet or a writer and I doubt that you're even a competent EE considering your attitude. Your post had nothing to do with the parent? WTF?

220Volts

[loddington]

Funny I thought we ran on 240 volts in Oz

Re:Do-it-yourself UPS? It's been done.

[Fulcrum of Evil]

I've even got a little portable touchpad for them to sign on, so it feels like the real thing.

If you really want it to feel like UPS Ground, shouldn't you kick the box around the back of the truck en route?

Myth.

[mindstrm]

Totaly myth.

Not possible.

Even if the resistance was only 1000 ohms, and it was most certainly a great deal higher, he would only have 9 mA, not 80.

Re:Myth.

[Uller-RM]

Not quite. Your skin's resistance is quite high... but once it pierces your skin (it takes an arc about 400V to do it, but if you stab yourself, tada), inner muscle and soft tissue racks up about 10 ohms an inch. And if applied across the heart, 9mA is enough to trigger fibrillation.

You don't need to be paranoid when working with lethal voltages... but you do need an ounce of common sense. Work with one hand.

(Cue web surfing while masturbating joke here - but I'm quite serious.)

Re:Myth.

[|<amikaze]

Work with one hand.

How do you use a multimeter with ONE hand?!?!

Re:Myth.

[Anonymous Coward]

>How do you use a multimeter with ONE hand?!?!

Alligator clip leads.

Re:Myth.

[rot26]

As we used to say in rokit sientist skool "volt's jolt, mil's kill".

Re:Myth.

[tzanger]

You don't need to be paranoid when working with lethal voltages... but you do need an ounce of common sense. Work with one hand.

That's not even enough. 60Hz will capacitively couple quite nicely through an inch of rubber sole to concrete.

One hand helps a lot, but it doesn't mean you can go grabbing conductors. :-)

Don't-do-it-yourself UPS

[AlexA]

So, if I didn't want to build my own UPS, what are some good brands to get for affordable yet good quality UPSes (reliable, has computer interface that Linux supports, etc.)? I've heard not so great stories about APS...

VA? Watts?

[plimsoll]

| The other thing that's irritating it that they
| rate these things in "VA" (watts?), when watt-
| hours would be a more useful to know.

APC has published a white paper that explains the differences between Watts and Volt-Amps.

Further, it explains why VA are really more relevant when figuring out which UPS would look good on you.

Re:VA? Watts?

[gerardrj]

From the introduction of that paper:

The power in Watts is the real power drawn by the equipment. Volt-Amps is called the "apparent power" and is the product of the voltage applied to the equipment times the current drawn by the equipment.

so what they're saying is: VA = volts * amps
And W =volts * amps

Now I'm no algebra expert but even I can see that W = VA.

Then to quote dictionary.com:

Volt-ampere: A unit of electric power equal to the product of one volt and one ampere, equivalent to one watt

So it seems to me that APS is the only entity that thinks W != VA ??

Re:VA? Watts?

[threephaseboy]

W=P=E*I ONLY for purely resistive loads.
W == less then E*I for inductive loads, like computers, motors, etc... anything with a power factor less then 1. On the other hand, VA == E*I for any device, and gives the total amount of power required by the device, not how much it is using.
(E == volts, I == amps)

rollyerown

[Anonymous Coward]

----got one of them home made "ups" thingees here. 36 deep cycle 6-volters in a series/parallel config for 24 volts dc, run through three trace charger/inverters. Get 120 and 240 VAC --> out. Hmm, lots of it, too... Power supply is 40 large solar pv panels. It seems to provide a lot of cushion ;^)

UPS Suicide

[Linuxb0y]

This's sure way to kill yourself.

Stupid stupid idea.

Absolutely. And there is a reason we don't do it.

[mindstrm]

It's totally impractical. You would have to ensure that no metal objects were in the house, or they would pick up the power as well.

Read up no Tesla, he was a fan of this. Lots of wireless lights in his labs. High frequency, high voltage electric fields really.

Non-redundant UPS problems

[Animats]

One problem with this is that your inverter may be less reliable than your power line, in which case you've made things worse.

There are modular inverters with N+1 redundancy, but those are usually seen only in large units.

Some words of advice on UPSes

[NewtonsLaw]

I have two UPSes -- I used to have three but one died a horrible death for no apparent reason.

The smallest unit I have is a 600VA no-name Taiwanese box with two 7A SLAs. It has no fan and, although it's just an SBS, it still runs hot as hell.

As a result of this hot running, I discovered that the SLAs tend to dry out rather quickly such that you get a much shorter time than you'd expect when the mains power goes off (as I discovered just the other night :-(

My other box is a Siemens 1KVA full-time UPS with forced ventilation and a bunch of other cool features.

It's worth noting that even a fan-cooled UPS such as the Siemens can run way too hot -- as I discovered about a year after I installed it.

Without warning, the UPS started screeming at me with a continuous alarm buzzer. It was still working but it was not at all happy.

On touching the case I discovered why -- it was too hot to touch.

I shut things down really quickly and opened up the case to see what was wrong...

Dust!

The intake holes in the front panel have a fine wire mesh over them and, since this UPS (like most others) lives on the floor under my desk, enough dust had been sucked into the holes to totally block them.

So here's a DC-AC inverter busy delivering about 500W of power to several computers and monitors -- but without the benefit of any cooling. No wonder it wasn't happy.

I blew the filters out with compressed air, checked that the fan was okay and put it back together. It's been working fine for nearly two years since -- albeit that I check and clean the intake meshes every few months now.

That the Siemens box was smart enough to warn me it was in distress (rather than just failing) shows that nobody ever regretted buying quality.

So.. rules of thumb for UPSes...

If it runs hot-- expect the batteries to last just 18 months to 2 years -- and don't wait until the power fails to find out that you should have changed them already.

If you have a fan-cooled UPS mount it up off the floor or check that the cooling holes are clear at regular intervals.

Re:Some words of advice on UPSes

[Anonymous Coward]

You could of course vacuuumclean your house at regular intervals....

And the idea scales well!

[zerofoo]

I did some network consulting at a lawfirm that had offices in a high-rise tower. They couldn't get the EPA permits granted for a diesel powered backup generator, so they built a "UPS" room.

The inverter came from these guys here.

They hooked up half a room full of 12 volt lead-acid batteries to charging systems and inverters and put the whole system under a vent hood. We never did figure out exactly how much runtime their server room had.

-ted

Health Issue

[Quirk]

Can anyone clarify if there are serious health issues from derivative fumes from the battery charging? A health worker once mentioned in passing that charging batteries, esp the larger ones, in closed areas, creates a gaseous discharge that is _very_ unhealthy to breath. I ran a google but came up empty on a precursory search. Anyone?

Re:Health Issue

[Agamous Child]

It is only an issue if you are smoking, or there are other sparks/flames, as batteries can emit Hydrogen (re: flammable) gas.

I guess inhaling hydrogen could be dangerous, I wouldn't want to do any long term personal studies.

Re:Health Issue

[Anonymous Coward]

I'd also guess that it wasn't the hydrogen per se, but maybe some of the sulfuric acid wafts out of the same vents as the hydrogen. Just a guess, tho.

do-it-yourself UPS is easy

[g4dget]

Get a laptop. They come with a built-in UPS, and the power management is tightly integrated with the BIOS. They also tend to be pretty energy efficient.

Standard Internet Horror Story

[_bobs.pizza_]

• some guy creates cool thing
• said guy puts directions on his homepage
• some bored /.er finds it, submits it to /.
• editor likes it, it gets posted
• INSTANT DEATH to the guy's homepage
• inventor guy looks at how many hits he's gotten, realizes why server is dead
• guy learns not to share innovations online

This is how we thank people that invent cool things in this day and age.

Re:Fixing APC Smart Rack UPS.. ---UPS Fire story..

[Mad Quacker]

The author cautions about taking an existing UPS and trying to add more, bigger or extra batteries. The power supply inside is built (cheaply) to deliver only the amount of current required to charge the battery it was designed for, and no more.

Actually the problem is that they were designed to run only for 5-10 minutes at a time. Instead of heatsinks they just use blocks of metal that have enough thermal mass to keep it within operation temperatures for that period of time.

I found out the hard way.. wired up an additional 25Ah in parallel with the 10Ah that came with it (rated for 500VA). Ran fine for 30 minutes. Then a burning smell and beeping for no reason (battery meter at ~40%). Unplugged it and immediately opened it up (30 seconds), as soon as I did one of the heatsinks (err lob of metal) fell onto the hardwood floor, with the semiconductor still attached glowing white hot. In about 1/2 sec it burst into flames (Oxygen starved from inside case!) and the whole block started to burn into the floor. Luckily I had some pliers to pick it up so it wouldn't burn the house down. There is still a big black square burnt into the floor. Branded by my ex-UPS.

I got damned lucky because I didn't drop the heatsink on any part of myself, I imagine any clothing would have caught fire instantly, etc.

In retrospect I suppose I could just add large heatsinks and a fan and it should work. The semiconductors have to be rated for the current, but the wasted energy just has no where to go.

Two too many voltage conversion steps

[nsayer]

Surely someone out there makes an ATX power supply that takes 12 VDC as an input. You could take a rather expensive component (the AC inverter) out of the picture and increase the overall efficiency by a measurable amount.

Oh, and the greeniacs out there will be no doubt pointing out that there's no particular reason that the AC->DC step couldn't be replaced by a bunch of solar panels and a charge controller. :-)

Unreal

[Anonymous Coward]

I can't believe this lame BS made it to /. How disappointing. I was expecting someone to show us how to procure power company transformers, set up battery banks, and roll our own power inverters using massive arrays of transistors. Blegh to this loser! BLEGH!

Late to the Party

[Agamous Child]

As someone who has spec'd out and designed industrial grade battery banks for electric utility substations, I would not suggest doing anything this person has done in a household that doesn't have these things:

1. Proper Ventilation (Like those hoods you see in Chem Class)
2. Proper Fire Safety Equipment (Chemical Fire Extinguisher as well as conventional water)
3. Proper Acid Retention and/or Mitigation (Chemical type Acid neutraliser) and a way to keep all of that acid from eating up your carpet)

Also, the household shouldn't have any of these things:

1. Small Children
2. Smokers (People who smoke)
3. Pets
4. Wives
5. Intelligent Human Beings

Oh, let's not forget Safety Glasses and a Hard hat while you sit at your computer... dufus should have gotten a regular old APC.

Re:Late to the Party

[Anonymous Coward]

He used sealed batteries, dipshit.

12v DC input ATX power supplies...

[Radi-0-head]

I think these are what you're looking for:

http://www.keypower.com/DC_power/DX-250H.htm

Grumble.

[Anonymous Coward]

"Of course you can mentally substitute U.S. 110 volts for Australian 220 volts wherever necessary"

Godamnit, not everyone on the internet is a f**in American!! You know this whole global network thing, actually spans the globe, oh damnit nevermind.

Re:Grumble.

[kentborg]

And if you are not in US, you don't have to substitute. (Presumably everyone who is not an American knows that fact.) The word was "can", not "must".

Americans, being rather insular (not all countries can equate "overseas" with "foreign"), sometimes need help dealing with the outside world, and they ARE a lot of the slashdot readership, so it is not efficient to tell them to do the conversion. (Isn't it?)

Oh, and not only folks in the USA need to convert from 220 (or 240). Mexico and Canada too. And Japan, they are 100 VAC. (Ever wonder why those little universal switching power supplies go all the way down to 100 volts? Not for California brownouts but for Japan.) I am sure there are others, but I can't recall them right now.

-kb, the American Kent whose daily paper is the International Herald Tribune.

P.S. 110 volts is low in the US. I think 117 is the nominal voltage, and I think of it as 120, for my outlets sometimes measure a smidge higher than that.

ups?

[THEbwana]

laptop? Works better. Thats why you find laptops in server rooms in the third world. Best ups you can get.
/m

beowulf cluster batteries?

[thogard]

At work we bought a 3kva upsonic ups. Its good for about 10 minutes. That just would not do so we hooked up 16 deep cycle batteries to the thing. Now it will run for about 4 hours on a full load and a very long time when we start pulling things offline. It takes 4 days to recharge the thing.

We got a UPS because it has a good inverter and auto switching and a built in charger. An inverter would have cost more. I've got a snmp card so I can measure different things.

You have to be careful about these things beause you get a large voltage and massive amounts of current. Our system has two 96 volt banks and good for at least 300 amps. That can kill and it can also cause batteries to explode. Treat these with the respect they deserve. We have a small circut that goes between each battery that has 4 led's that let us know if any one of the batteries go bad. Its also hooked to a monitor system so we can get real time alarms if anything goes bad.

Deep Cycle Battery experience with BBU/UPS units

[octalman]

When the gel cell battery in a 450 W TrippLite battery backup unit failed (after over 12 years in service), and a replacement battery was not readily available (I'm in the boonies), I bought a deep cycle battery at WalMart and hacked the connectors and cables. It has now been in service over four years with no problems, and has powered through many power sags and interruptions.

That worked so well that when the battery in a second, similar TrippLite failed (also after about 12 years), I did the same with it. It has powered two old computers through power problems for about two years. Both batteries are reasonably well ventilated and sit in polyethylene tubs. Though the users have been cautioned to top up the cells with distilled water occasionally, I don't think it has actually ever been done :-))

UPS size twaddle (was Re:The Remains)

[Anonymous Coward]

Are you sure you had a 50,000KVA UPS in 3 fridge-sized units?

Surely something nearer 500KVA is what you saw - we use 3 of these for two acres of kit in racks.

The largest I've ever seen is a 6,000KVA unit which comes as a 28', 30 tonne trailer container. It's not 3 fridge sized.

It can feel great to boast but, for crying out loud, get some of the facts right - especially as you emphasize the various numbers.

Moderating such nonsense to a 5 doesn't help either, guys.

Re:UPS size twaddle (was Re:The Remains)

[sysadmn]

Indeed. Just last week I saw a 24,000kVA backup power system. It's 5 tractor trailers, one of which contains a modified jet engine. The bad news is that it puts out 13.8kV or more. CS majors - don't hook that to your PC. Rent one today!

DC - AC - DC conversion?

[Anonymous Coward]

If you use a battery, why not supply 12V, 5V and 3.3V directly. Why do DC-AC conversion and then AC-DC conversion?

KISS

Re:DC - AC - DC conversion?

[TheCubic]

This is not easy, Coward. You'd need a giant voltage regulator setup. However, if you want to build a circuit to change 12V to 5V that _doesn't_ suck, you would need to convert it to AC first because AC is the only type of current that can be transformed by coils. So, inverting the power is less complicated than scrweing with the DC.

The power supply already does the job of regulating power, why get rid of it?

Re:DC - AC - DC conversion?

[Glumdalclitch]

DC-DC converters are often actually DC-AC-DC
converters. They waste less electricity in
terms of resistors. Otherwise you'd need
three separate batteries: 12v, 5v, 3.3v.

everyone runs 220-240

[Anonymous Coward]

220 V are the same as 240, because it has a 10% legal variation, and it is considered the same voltage (1110-140 are the same in fact)

trust me, i'm an electrical enginner, not a computer geek ;D

oops!

[Anonymous Coward]

I read the headline, and thought it was a DIY package-delivery solution!

Used / Refurbs / Hand-me-downs

[tweakt]

I'll stick with my APC Back-UPS Pro 1000 I got for $100 at a computer show. 670W of capacity, 1000VA, will power my workstation for several hours.

Look for people selling these from companies who've tossed them when upgrading to larger more centralized backup power (APC silicon, etc).

There was another rackmount 1400VA unit for $100 when I went back a few weeks later... I was a little upset but what the hell 1000 is enough for me, and I dont have a rack in my apartment (though I'd like to) ;-)

about VA's and Wh

[Anonymous Coward]

Va are voltamperes, it is (more or less) volts*amperes, and it is stimating the amount of energy needed tuo pass throgh te electric line to feed your system (and no voltameperes are not watts, watts in fact, are lesser than voltamperes, specialliy in high inductive charges, as electronic ones).

how they are related? well, you have that thing cos fi, if we call s to VA's and we calll p ti the watts, we have that
s = p * cos fi
you know

trust me, i'm electrical engineer, and not a computer geek ;D

This is good and all but.....

[cjc84]

I want to see someone build a UPS inside a PC that takes in the standard 110V (or 220 V for our friends across the pond), cleans it, provides power back up storage capibilities, and outputs this power into the many voltages required by a PC. And also providing the neccessary wattage required by a fully-loaded PC. Next step would be to make a laprop charging cord that is a UPS too.

Surge protection..

[dk.r*nger]

I live in a very well developed country and power outages are unheard of. It's been serveral years since we had one. But then the other night there was a thunder, and my DSL adapter got fried.

ISP replaced it not questions asked, but what it that had been my beowolf cluster of [insert cool tech here]?

- Ranger

Re:CS and EE degrees, etc...

[Anonymous Coward]

You wouldn't want a person without a CS degree writing software; we shouldn't have folks without EE degrees designing power supplies.

You're offending many by making such a statement. I know of many people who have desinged power supplies, radio equipment, etc.. that never even went to college. Some of the greatest inventions and discoveries in the world have been made by those lacking a college education. Not to mention numerous software packages, some which rival their commercial counterparts, written by those with no college degree.

One word of warning...

[wirehead_rick]

that was not particularly covered in the article.

I used to design UPS's for a major American UPS mfr. The author slightly mentioned that you would not want to use a normal UPS for continuous operation due to overheating. He is correct but for the wrong reason. It is NOT overheating of the battery cables you have to worry about. It is the Transformer.

Since the Transformer is the biggest cost item next to the Battery they are highly optimized for the performance/price point. That means a transformer designed to run at 400VA for 3 minutes will probably melt into a glob of laquer, copper, and steel in about 20 minutes. Of course that also means it could short out, catch fire, or send unknown voltages to your computer possibly destroying your computer PS.

Just as a point of reference the industry has made a distinction between continuous duty and back-up supplies. UPS means temporary supply to allow you to save data. Inverter means continous duty.

If you wish to try this project I make two suggestions:

1. Use or purchase an Inverter. Tripp Lite sells the PV series inverters which were designed to be used exactly in the fashion of the unit in that article. They also sell APS's which are UPS's that _are_ continous duty.

2. If you MUST use a UPS inverter, then get one that is overrated by at least 10 to 1 in VA handling capability. Depending on the UPS you get this may not be enough, but it will get you close.

3. If you are really ambitious, replace the UPS transformer with a much bigger one. Keep in mind that the power handling of the drive circuitry is important too, but hey - you want to tinker, right? Just make sure you understand the proper step-up ratio and winding configuration of the original transformer.

Australia Centric

[Anonymous Coward]

What's with everything around here being
centered on Australia/Europe. Us yanks
read Slashdot too you know.

Not only that

[Sycraft-fu]

But UPS battires are just simple Lead-Acid battires. Generally nice sealed ones, but none the less still a Lead-Acid battery which can be built fairly cheaply. They are, after all, a very old technology. Laptops, needing a much better power to weight ratio use more advanced battery technologies. At a minimum they use something like nickel metal hydride and generally all newer laptops use something like lithium ion battires. Well, while these provide great storage for their weight, they are much more expensive to construct and hence more expensive to buy.

I thought of this also

[Anonymous Coward]

But on a bit bigger scale, 2x300Ah batteries in serie, but te battery charger cost 1000+ euro's the converter around 500 euro's battries 250 euro's. So it's not cheap but I'll stay on line all day if the power falls. I think it's even big enough to run lights and alarm clock, videos etc.

And mayby it's possible to charge them (partly) with solar power.

And to make it just a little bit more fun: Add a diesel engine with a 10kW elektric motor.

One day I'll build it 8).

Why not a DIY operating system?

[ReelOddeeo]

From the screen of the computer, I can see that he builds a DIY UPS, but he doesn't run a DIY operating system.

Mr. Mom...

[dman123]

220, 221... whatever it takes.

As long as we're talking about ghetto UPSes

[TheCubic]

When I was shopping in my local store I found dead power backup units for $5 each and fixed them up to create several UPSes. I used a car battery (type 24) for power storage. I haven't used it much; It's really bulky with the car battery. The supplies are rated at about 500W (and they can power a lot) and work great.

When I was building one of them I accidentally hooked the battery up backwards and a few transistors popped. The part that was damaged was the charger and line in; i turned it into an inverter for my car (with much success), and have powered TVs off of it and such.

One time I dropped a fan across the car battery and the 24-gauge wire burnt up like crazy. The advice I'd have is to seal up the battery as soon as possible so stupid crap like that doesn't happen. Oh, also use the proper gauge (a/l 10 gauge, 12 if you're not going to put much load on it), if you put 24 gauge on it it will burn, oh yes...

but what about UPS monitoring??

[e40]

He says nothing about monitoring, which is a big drawback to this approach. Did he ignore it because he intends anyone to build in massive over-capacity?

substitute U.S. 110 volts for Australian 220?

[The Vorlon]

You mean even the volts have a poor exchange rate in Australia?

I've heard of weak currencies, but never of weak electrical potentialcies.

Parallel Extra Batteries

[Mr_Perl]

A friend of mine works for a hospital which recently changed out all their batteries in their UPS as they do every few years. He salvaged a few good ones, and gave me a couple.

I connected them in parallel to the power connectors on my APC UPS and can now expect many more minutes of power outage without interruption.

Your local hospital might be a good source of batteries for a project like this since they have to pay to dispose of the batteries anyway.

Software support

[rossz]

What good is a homebrew UPS if it doesn't support decent management software such as NUT?

Having a UPS means nothing if you lose power and the server dies when the battery runs out. You want the system to gracefully shutdown when the battery level becomes critical.

Is it just me?

[Jay L]

A UPS is an emergency backup solution for mission-critical applications. Building a UPS out of spare parts based on instructions from a web site seems like sewing a parachute using recycled grocery bags with a pattern from McCall's.

Re:Is it just me?

[Anonymous Coward]

It's just you. He explains why this makes sense in certain situations, and the explanation seems quite reasonable. Obviously you wouldn't use this approach for a production database server. But in a lab, with plenty of bench supplies etc., using daisychained batteries and an inverter seems perfectly reasonable and is probably actually safer than many commercial UPS black-box solutions.

What about DC-DC converters ?

[Anonymous Coward]

You're right! DC - AC - DC conversion is not only silly, but it lead to power loss at every conversion stage by Joule effect (heat). We want to power the computer, not to heat the computer room. :-)

My question is, Why can't we find a power supply that looks like a normal computer PSU, that has the same electrical and mechanical specifications than a computer PSU, but the primary power is a DC input, instead of an AC one.

Plus, you can stuff all the input power measurement and management stuff inside the box, with an interface to the mobo, this would probably be the best PSU/UPS available ever.

DC light bulbs

[Frank T. Lofaro Jr.]

"Regular" light bulbs should run fine (and actually last longer) on DC.

Re:DC light bulbs

[Anonymous Coward]

"Regular" light bulbs should run fine (and actually last longer) on DC.

I've heard the opposite. An incandecent bulb will run just fine off of DC since it's just a resistor run hot enough it glows. However once the filament gets hot the metal is suseptible to metal creep. The metal becomes somewhat fluid at such high temps and the metal will slowly move with the electrical current, which creates weak points in the filament. Once the weak spots get to the point it cannot withstand the heat it will blow violently and often arc for some time. The bulb may blow so violently that the glass will shatter as well. A bulb on AC will not do this since the current alternates the current goes in one direction as much as the other so the creep will mostly cancel out. Also arcing is minimal since as the current alternates many times per second it also goes through zero volts, which normally breaks the arc quickly.

Metal creep is a common problem on ICs since its powered by DC and if you run the circuit a little too hot (as in overclocking your PC) the circuit may die suddenly because of this. I've talked to people at the university that worked in an old building years ago that for some reason had high voltage DC for the lights using common 120V bulbs. They said they looked a little funny as the voltage wasn't quite right, and had seen the bulbs blow violently and often.

Re:Deep Cycle Battery experience with BBU/UPS unit

[Pontiac]

If you want a cheep sealed battery with automotive capacity just run down to Schucks, Checker, Kragen, Autozone, pep boys, wherever and pick up an Optima Yellow top (deep cycle). Then you don't have to worry about hydrogen build-up in your computer room.
These batterys are sealed wet cells that will last for years.. expect to drop about $150-200 US

Optima's and other type of sealed automotive batterys can be ordered from either Summit Racing or Jegs

These are great ideas

[GPS Pilot]

Think about how the cost of a whole computing system could be reduced.

A PC that is designed to be permanently connected to a UPS that provides DC power would need no power supply. Not only would this this probably shave $40 off the retail cost of the PC; lack of a power supply would make the PC smaller, lighter, and more electrically efficient, and reduce thermal output.

The problem is that your monitor, modem, etc. all expect AC power.

Just as the PC would have to be redesigned to use DC-only power, peripherals would too. But it's doable. My external modem and printer use AC-to-DC adapters, and both CRT and LCD monitors can easily be designed to run off of DC (as Apple has done -- its "ADC" series monitors all run off of 28 volts DC). Once all your peripherals no longer use AC-to-DC converters, then the UPS no longer has to contain a DC-to-AC inverter. Major cost and efficiency savings all around!

Actually its 120 Volts, not 110 Volts

[displacer]

Check it with a multimeter some time, make sure the meter is set for voltage reading though or you'll get a nastsy surprise.

My laptop has a built-in UPS ....

[rbook]

My laptop has a built-in UPS that lets it run for 2-3 hours after a power outage -- that's a lot longer (and it's more portable) than the standalone commercial ones, and even longer than this DIY version!

alternator? huh? no. try : STARTER MOTOR

[Anonymous Coward]

and where the fuck did you pull 3400 amps from? your ass?

alternator? no. STARTER MOTOR.

[Anonymous Coward]

moron.

Home Made Car Battery UPS

[Anonymous Coward]

We have a bigger version of this going on the plant floor at work. We use a car battery, ac to dc converter and a battery changer housed in a locked cart. When the battery is fully charged we have been told it should go for 32h without needing to be recharged. We only plug it in at night and I've seen it run without the charger being plugged in for 12H without an issue.

A little more info...

[cr0sh]

A few people on here are bemoaning the fact that this "ghetto" UPS doesn't have monitoring. Even the author of the article notes this. However, building such a monitor wouldn't be too difficult.

Basically, you are looking at a relatively simple voltage window comparator circuit. Most of these circuits use op-amps arranged in a differential mode to provide 2 or 3 "windows", and typically light up LEDs to show "high", "medium", and "low" voltage levels. Simple digital signal probes do the same. Most of the time, these devices can be built using cheap op-amps or comparator ICs that house four comparators in a single DIP package. Hook the LED lines to a PIC/MAX232 system and monitor the data via RS-232. Or, simpler - monitor the status of the lines using the parallel port.

The "el-cheapo" solution is to just simple start the shut-down as soon as power is completely lost. Drop a relay across the 120 VAC input, then have a 5V source (from the battery and a 7805) switched "on" when the relay is disengaged when the voltage fails. Run the 5VDC to a opto-isolator circuit (to isolate the computer port from the mains at the relay), and the ouput from the opto-isolator to the parallel port or serial port (you could monitor this directly). Configure the software monitor to check every so often, and if the power is indicated to be "out" after 15 or so seconds, begin the shutdown sequence (this will allow for transients in power that might occur - you could up this to however long you wish).

Software would have to be written for both of these solutions, but it would be rather simple, for either *nix or 'doze.

In regard to the danger of this kind of "battery-box" solution - you definitely have to be careful with this, when it is on, and "off" (ie, doing the UPS thing). LA batteries can source a lot of current - you can easily make a cheapo stick welder with a couple of good 12V car batteries - that is serious current. Also, when an LA battery (actually, any battery) is under load, it will generate heat, and in the case of an LA battery, a lot of heat can be generated. This heat can cause the electrolyte to "boil", forming funky gasses. The batteries can also explode (heck, I have even personally witnessed dry cells explode). If you want to see an "interesting" site, go to an electronics junkyard and look for an old "heavy duty" UPS (look for refrigerator size boxes needing 440VAC input). If the batteries are still in the box, take a careful look at them - you might notice that they are "swelled", some may have even leaked or burst. This is because the UPS kicked on, and remained on for a VERY long time, and the batteries literally "cooked".

What the one poster said about having cleanup supplies, etc - yeah, that could be needed. If it was me, I would store the UPS outside my house, in a ventilated shed or something...

Not 60 Euros, tenfold error?

[stere0]

You probably meant 0.60 Euros

Re:Deep Cycle Battery experience with BBU/UPS unit

[Anonymous Coward]

Or go to (or get a friend to go) to Costco and get the same Optima Yellow top deep cycle battery for $100.

Re:Be Careful - Don't try this at home

[masonc]

As an electrician in a former life, and having a lot of experience with UPS's, unless you really know what you are doing, this is a project best left to the crazy guys.
Large numbers of Lead Acid batteries are extremely dangerous, I have twelve heavy duty cells and I take extreme care around them.
Also, this design provides no way to equalize the batteries, which will ensure they will die prematurely. UPS technology is very complex.
I have a 10 year old 3.1 kVA Best UPS that has 90,000 hours on it. They are available second hand for pennies, much better idea than trying to build a half assed experiment.

Typically "harsh" weather isn't required

[lingon]

However, in many modern countries (perhaps yours excluded) power is generated using modern techniques that are impervious to all but the most severe weather

How about the following situation: Winter. Heavy snowfall. The temperature is one or two degrees above freezing (thus making the snow a) very heavy and b) very "sticky"). The snow accumulates on the nearby trees surrounding the lines, making them VERY heavy. Old trees cannot withstand the extra weight and they fall on the power lines. This happens a few times every winter in Sweden (where I live).

the transmission lines are underground

No, they aren't. All lines in towns and cities are underground, granted, but not in the country. Do you know the cost of putting all underground? I don't think they do that even where you live.

More info and summary of some good points made...

[Hyped01]

First, to summarize some points made:

Creating a circuit to monitor one is easy.

Creating a circuit and software to allow it to "interact" with a computer is easy.

The design, contrary to a previous post can and will provide VERY stable power - far better than most "household" UPS's sold - because you are always running off the inverter - if you buy good quality true sine-wave inverters. StatPower is a good source of them and you can buy them cheaply from JC Whitney - AND - JCW offers a 60 day unconditional money back guarantee on everything they sell - you wont find better customer service. Each and every order shipped by them comes with prepaid return labels pre-authorized for merchandise returns. No annoying calls for an RMA number and such. Simply drop the item back in the box, slap the supplied label on it and call UPS for a pickup. (in 15 years, I havent returned more than 2 things... YMMV... instant credits on them).

Adding a fan(s) and enclosure for cooling and "safety" (not dropping something across the battery leads) is easy. Using a thermistor to regulate when the fan comes on is child's play.

Wire sizes as already noted are extremely important. Whenever working with DC, keep in mind the wires need to be large (ie: low gauge). Generally, in case of overcurrent situations, I use 2-4 gauge less than "required"). You cannot use AC current wiring specs to determine wire gauge on DC wiring - unless you want a puddle of copper and insulation and possibly a neat little fire. Because AC does just what the name implies - alternate - heat buildup for the same amount of current is a lot less. Also keep in mind, for longer DC runs, you need lower gauges than for shorter ones of the same load. (there are a dozen sites on line that will help with this info - look up DC house wiring to find some).

Installing a breaker type automotive fuse block of the appropriate size will facilitate avoiding a number of problems. Again, make sure breaker(s) and wires are properly rated for the load you wish to pull.

Buying an inverter that only generates the load being drawn will help increase efficiency. There are some that use only milliamps in "idle" mode (no load, but online).

Exide is the place for batteries... besides the fact that they make more brands of batteries than most of you could imagine (as a comparison, 40 "brands" of soap on the shelf at the supermarket, 5 major soap companies...), they also specialize in industrial deep cycle batteries and seem to have the size factor at a very acceptable level for the current they store and "create". For instance, the one we have been looking at for a similar (house level) application is an Exide 840ah 24v 6 hour rated battery... (you do the math... it'd power your computer for a very very long time...) they are designed for the in-building forklifts you can find at various Home-Depot's and such. Thus, charge, full/near-full discharge during heavy use, and repeat daily abuse and they handle them well. Exide makes smaller versions as well. All the way down to the RayOVac (and bigger brand name) batteries. Keep in mind many such battery solutions will require a 24V charger and 24V inverter - or 2 inverters in series. They are ideal for big UPS' that use 4 12V batteries.

If you are serious about this, battery quality does count big time. The correct lead acid battery type will last YEARS of continuous charge, discharge cycles. We used a bunch Panasonic made for an entertainment venue a number of years back and got 8 (on the first to die) to 12 years out of them doing 2 charge/discharge cycles a day every day. I wouldnt recommend them any more (Panasonic) as they far exceeded the rated life and charging cycle - which Panasonic rectified when they revamped the battery series. 2 years on the same model number battery of the new design.

These same plans can also be used with solar, wind and water power generation systems to charge, maintain or top off batteries with a little planning - as well as with backup generators. Thus, you can use a cheap backup generator in your house or business to create the DC charging current to then provide beautifully stable AC current via the battery(ies) and inverter(s).

For larger applications (VERY large), consider one of the "household" inverters... they are chainable to create 240V (which is really 2 120V lines in cyclic opposition), and usually contain charging units in them that you can provide power to via your incoming utility line, generator, solar, wind, etc. For 4400 Watts expect to pay about $2500 for the inverter, but expect the power to exceed the quality of your utility company 130% of the time and keep your batteries "professionally" charged. I am talking about this as a solution because it is ideal for companies with big server rooms wanting to use a similar method as described on the web page but for higher loads to maintain a lot of servers. It would be very simple to use an Exide 840ah and a Trace inverter (the makers of many other brands of inverters too like StatPower and PortaPower) to power a server room for hours or days.

ASE Americas makes 315Watt and down solar panels in roof mount sizes with high efficiency ratings and certification for many areas and setups. They come in a wide range of voltages per wattage output (meaning you can mix and match inverter/battery/solar cell options to create an ideal system). Solar would be more likely for people out in nowhere areas who needed long backup times or wanted to operate entirely off-grid.

Price shop like crazy for your inverter, batteries and more... I've seen the 4000W Trace inverters as high as $5800 and as low as $2490. Same model, different places. Same probably applies to the lower watt models like the StatPower (which have models to 3000W). Both StatPower and Trace home inverters feature very high surge ratings and stable "true-sine" power output on their higher end models. For StatPower, JCWhitney usually cannot be beat on price [except on auctions (eBay maybe?) and closeouts] and cannot be beat on customer satisfaction.

Some links for reference:
- Inverter
- 12V House
- Exide
- ASE Americas - Rob www.Hyperforce.com

Confirmed..

[Patrick Cable II]

Yes, and this story was confirmed i believe by the Darwin Awards committee. (fyi)