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Capacitors to Replace Batteries?
An anonymous reader writes "MIT's Joel Schindall plans to use old technology in a new way with nanotubes.
'We made the connection that perhaps we could take an old product, a capacitor, and use a new technology, nanotechnology, to make that old product in a new way.'
Capacitors contain energy as an electric field of charged particles created by two metal electrodes, and capacitors charge faster and last longer than normal batteries, but the problem is that storage capacity is proportional to the surface area of the battery's electrodes.
MIT researchers solved this by covering the electrodes with millions of nanotubes.
'It's better for the environment, because it allows the user to not worry about replacing his battery,' he says. 'It can be discharged and charged hundreds of thousands of times, essentially lasting longer than the life of the equipment with which it is associated.'"
I'm sick of that bloody rabbit. Now it's going to last forever. Perfect.
Meta will eat itself
How do I manufactured super nanotube capacitor array?
More to the point, how do you do that on a mass scale? Yeah, they don't actually design the mass production stuff at MIT now do they?
Finally... the flux capacitor we've all been looking for!
I thought the charge was on the parts of the plates nearest each other, so the surface area would only be that of the ends of the nano-tubes. This would be smaller than if they had a flat plate!
Philip Jose Farmer predicted "batacitors" in his novels decades ago. Chalk annother one up for life imitating science fiction.
..to only allow opration in one's own high draining devices?
Fine, as long as it doesn't buldge, leak, dry out... like two of my abit mobos and no telling how many others. Besides it's never going to happen and more than flying cars or robotic lovers.
The fast charge has its obvious benefits, but I'm wondering about the durability of such nanotube filaments in the face of, say, the treatment your average laptop battery would have. Are these things resilient enough to be bashed around?
Are these capacitors only likely to be suitable for for small scale charges/discharges? Mobile phones? laptops? cars themselves?
More questions than insights, I'm afraid, but I find it fascinating
Thats just fantastic, sounds like the ideal replacment for batteries, and puts fuel cells out of business for small consumer products like laptops I'd have though, especially as they wouldn't cause any problems on planes.
hydrogen fuel cells would still be great for larger things like cars.
could these be produced in a way to fit in existing devices as soon as possible? I'f this really is safer for the environment, I'd love to see these asap, especially as most batteries are standard sizes already, even inside a laptop battery there are often (always?) muliple standard sized cells.
I hope they're easilly recyclable too, for when they do finally fail.
Where others see the potential to supply low power for a long time, I can see much potential for supplying a hellofalotta power for a very short time. That is, take a few of these capacitors and join them together in a combination of series and parellel until you have something like a 70V, 5F mega-capacitor. Charge it up. Insert probes into, well, anything conductive. Turn on.
Splat.
Fun.
With its longer life and faster recharge time. I wonder if this could lead to an electric car that is good for the masses where they can cross country and take only 5 to 10 minutes to recharge. That is the primary reason why the Electric Car never made popularity it is because it is not convenient enough for normal people.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
I guess this means laptop designers will have no excuse to not make a battery that fits in multiple models even if that means models that are 'generationally' different.
So, when they don't do such design, we'll know it's most likely because of bad design in the first place or sheer I-don't-care-what-you-think-give-me-your-money-... -again kind of attitude.
I'm not saying they don't have a right to do so. What I am saying is that the company that doesn't do so might have the consumer's pleasure more at heart.
actually, I suppose it could well be more environmentally friendly to just use these, if they can provide power on par with, or greater than fuel cells for size/weight. There wouldn't be any emissions with a capacitor? and weather you use fuel cells or these, there are power requirments to charge them/produce the hydrogen for their respective systems..
This is a really good plan in theory and on "cost is no object" plans it's a great idea BUT theres no real way this can replace batteries because your cost per unit is going to be much higher than standard batteries already are. No one is going to pay $20 for a pack of AAAs that you can get for $4 and just have to replace in six months.
You implied that a Slashdot comment author has a wife/girlfriend. Please don't. It only makes the inmates restless.
http://gtresearchnews.gatech.edu/newsrelease/nanoc apacitors.htm
http://www.physorg.com/news10525.html
Summary says this technology would allow batteries to charge faster. It's a big understatement since the article says they would only need a few seconds to be fully charged...
First, safety. One of the amazingly cool things about capacitors is that they can deliver all their charge over the course of a few milliseconds. This makes them very useful for things like strobelights and subwoofers. But it can be very, very dangerous: What happens if you drop your in the toilet? Or you drop your iPod and it gets run over by a car? If they have batteries, a short circuit will cause the battery to get warm for a while, or it will release some slightly caustic goo and you have to wash your hands. But if they have capacitors, you get an explosion and a violent electrical arc.
Second, durability. You can beat the hell out of a chemical battery, expose it to shock and vibration to no end and it will continue to operate. These nanotubes, OTOH look awfully easy to break. Breakage could cause two things to happen: loss of capacitance, or worse, an internal short circuit, and see above.
It will be interesting to see how these two problems are addressed, or if these cool toys will be relegated to industrial and other controlled-environment applications.
This is not my sandwich.
This article seems to suggest that capacitors are just an "older version" of batteries. Capacitors are not batteries at all. They are two different things. One creates a charge. The other simply stores a charge.
This is similar to a pump in some water that can create a higher pressure, and a bucket which can store water and release it later. Two different things.
Now, I'm not saying that you can't use big capacitors to power stuff or do what the article is suggesting. I'm just saying the premise is a bit misleading.
Yeesh... It switches between the terms battery and capacitor like they are interchangable. It's really annoying because in one sentence they use capacitor and then in the other they use battery. Battery stores energy using chemistry while a capacitor stores energy in electric fields.
Ooo man the floppy drive is broken. No wait. The computer is just upside down.
TFA says nothing about what kind of capacity improvements we're talking about here. Can anybody offer some insight? What kind of a charge will they be able to hold compared to today's chemical equivalents?
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Some time ago a 10 uF capacitor in a PSU exploded close to my face while servicing a PC. Luckily the PSU box was pretty well robust, and I had no injuries at all, but I'll remember for ever the loud BANG that followed (with a lot of smoke). I wonder if the same could happen by misfortune with one of these devices. AFAIK cellphone batteries seldom explode, so I am not so sure if capacitors would be a safer alternative.
Capacitors also have another difference: they can be (dis)charged extremely quickly. That means you will be able to recharge very quickly (if you have a spiffy charger), but I wouldn't want to drop a capacitor powered cellphone in the toilet.....
10 ?"Hello World" life was simple then
I'd gladly pay 4 times (or more) the price of regular batteries to have batteries that recharge in seconds and never need replacing. This will be great in cell phones and laptops, too.
Really, the true test will be if it can handle the load of a Hello Kitty Vibrator.
Whew! This water sure is cold!
I would pay 20 bucks for a pack of AAA batteries that had a life-span longer than the device I used them in and recharged in seconds instead of minutes. I don't know of any batteries that last 6 months (unless you mean they last 6 months in something like a tv remote).
Uhh... nanotubes easy to break? Since when? They're the only material strong enough for a practical space elevator! Think a bit about that.
On the contrary, if I have the option to buy a pack of two batteries for $20, or 4 for $4, and the two batteries will charge "in seconds" and last for hundreds or thousands of cycles, after just ten cycles I have "free batteries".
I go through AAs very quickly because of my discman, I know I'd be interested at a $20 pricepoint.
The sea changes color, but the sea does not change.
Perhaps, though, such batteries might be useful for (relatively) expensive systems that must often be recharged (i.e. laptops, razor, just about any large electronic commodity...
This Citizen watch is solar-powered and stores electricity in a capacitor rather than a battery. The capacitor rumoredly wears out after 5 years or so (hence, the warranty only lasts that long...).
:-) (If you're ridiculously-loaded and/or exceptionally-generous, it'd make a fine father's day gift I'm sure.)
It's a great watch, BTW, for anybody looking for a decent new watch.
Is Capitalism Good for the Poor?
The problem with capacitors is energy density. They can charge and discharge quickly, but the amount of energy per unit volume or per unit weight is usually not very good, even compared to batteries.
New supercapacitors (existing term, really) will improve the energy per weight or energy per volume, but they may cost more (energy per dollar).
If this is cheap and hig density, it could be a great step forward.
PS, check out the powerlabs guys. They do lots of dangerous stuff with bit caps
http://www.powerlabs.org/railgun.htm
My experience with capacitors is limited but I do know that they are extremely dangerous. I do distinctly remember having to discharge the capacitors in my arcade monitor in order to replace some circuitry. This involved a screwdriver with a grounded chain soldered onto it, some rudder gloves, and some flinching like a little school girl when you hear that loud pop from the discharge. I'm not entirely certain I'd want this sort of thing powering my laptops and cell phones.
No one is going to pay $20 for a pack of AAAs that you can get for $4 and just have to replace in six months.
People already pay twice as much for lithium AAAs that are lighter and last longer. How much would people pay for something that you can recharge repeatedly for years to come, and that packs more power than a regular alkaline? Don't know, but there's probably a market if the price is "only" five times as much as regular batteries.
And don't forget about using this tech in your iPod or other portable energy-sucker. It wouldn't lose the ability to charge after a year, it would recharge a lot more quickly, yadda ya.
Nanotubes are extremely strong.
As for safety, just like Li-Ion batteries have safety devices, I would imagine a "batacitor" would probably have a current limiting device inside a casing of adequate strength (and waterproofness), so the current draw from exposed terminals couldn't reach dangerous levels.
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If you use your math, the two power sources are equivalent so long as whatever being powered lasts 2 1/2 years. It also fails to account for the fact that batteries come in many different stripes that match different needs - cell phones, watches, cars, etc. The world of batteries is not defined by AAA and surely there are applications where this new tech would be perfect.
Seems like I miss something. It's not the area of the capacitor that matters (yes, I know the formula C=A/d for flat electrodes) but an "effective area". These capacitors are supposedly two flat or nearly flat substrate surfaces each coved with nanotube "fur". There is a gap between these two electrodes. The gap is much larger that the thickness of the nanotube. Consequently, the effective area of the capacitor is not much larger than the area of the flat substrate electode. What's the advantage of the "fur"? I would understand if [+] and [-] charged nanotubes were alternating inside the fur, but it's clearly not the case judging from the picture.
For instance, take a wire, cut it in half and separate two pieces by a small gap. That's a capacitor. Its capacitance is going to be somewhat larger than the A1/d where A1 is the area of the wire crossection, and a lot smaller than A2/d where A2 is the full surface area of the wire. The same applies to nanotubes.
So, obviously, they are doing it differently. How?
I could finally have my FLYING CAR? :-)
The problem with quotes on the internet, is that nobody bothers to check their veracity. -- Abraham Lincoln
The capacitance isn't just a function of raw surface area. If that were the case, you could double the capacitance just by roughing up the surface of the capacitor plates. The contribution of any spot on the surface depends on the area of that spot and the distance between it and another oppositely charged surface as well as the dielectric constant of the material between the plates. You can increase the surface area as much as you want but you still have to get the surfaces to line up with each other.
It is hard to exceed a certain energy storage on a capacitor. As you move the plates together, the capacitance goes up and you can store more charge per volt. The breakdown voltage goes down as you move the plates together. So you can store a small charge at a high voltage or you can store a large charge at a low voltage. For a capacitor of a given volume, you can store only so much energy depending on the breakdown voltage of the dielectric material.
I don't doubt that you can double or triple the energy storage of capacitors compared with current technology. On the other hand, I am very skeptical about the possibility of getting enough capacitance to store enough energy to be a general purpose battery replacement.
I leave it to you as an exercise to calculate the capacitance of a 2 volt capacitor necessary to store one amp hour. ie. something similar to an AA battery cell.
Dude, You've obviously never shorted out a NICAD cell before. The wire turns red hot and the insulation melts. The NICAD just says 'Is that all you've got? CoMe On! FeeL the BuRn BabY!' --Tarp
You have never created an internal short circuit on a conventional (rechargable) battery, did you? It is also able to deliver all the stored energy on an explosion that will take your hand away.
Now, batteries don't explode all the time, because they are well blinded. Capacitors are less dangerous (carry less energy), so they are not that well blinded, and explode often. There is nothing stopping the people from making blinded capacitos out of economics, and it could be even safer than battteries, because there is no ion trading going on.
Rethinking email
I wonder what They'd do about the exponential discharge...Everyone knows batteries discharge much more smoothly...
If they have batteries, a short circuit will cause the battery to get warm for a while, or it will release some slightly caustic goo and you have to wash your hands.
:-/
Sorry, that's incorrect.
Try shorting a car battery with a screwdriver and tell me there isn't a violent electrical arc. Also, NiCads (and I believe NiMH) have very low internal resistance - if shorted, they can literally explode as they overheat dramatically. You're confusing this with non-rechargeable batteries, which behave as you describe.
Also, capacitors deliver charge at a rate dependent on the impedance of the load they're driving. It would be very straightforward to put a small resistor in the package containing the capacitor, so that the current out of it is limited.
Regarding the short-circuiting, capacitors require overlapping surfaces that are electrically insulated from each other. That means if you're using nanotubes, you'll want both sides covered in nanotube "fuzz" and the two sides then pushed together so that the two intertwine. This means that one (or preferably both) sides need their nanotubes coated with some kind of insulating material for it to work, otherwise the nanotubes will simply short out, and then you won't have a capacitor any more. And that means you won't get short circuits from random broken nanotubes in the structure.
Fragility I don't know about, but since carbon nanotubes are the strongest substance currently known, I suspect it's not going to be a huge problem. Also consider that the whole thing could easily be encapsulated in some solid insulating block so that it's a single physical chunk (remember that carbon isn't a metal so there are no significant expansion/contraction issues with heat). Batteries are only as solid as they are because they've got a solid metal case encapsulating well-packed electrodes and electrolyte - try dropping a plastic-case car battery from a height and tell us how solid it is.
Given how desperate battery manufacturers are for any kind of edge, I imagine this will be rushed to market as fast as physically possible!
Grab.
Even a regular alkaline battery can get pretty hot as I found out when I had a 9v battery in my pocket with a handful of change.
-William Shatner can be neither created nor destroyed.
No clues given as to the potential amount of power that can be stored though ?
Honestly, when you get your new state of the art motherboard with quad-SLI and all the latest bells and whistles along with Dual Quad-core CPUs and 4 Dual-GPU video cards all in a lovely brushed aluminum case with see thru side panels and neon lights, it kind of breaks your heart when you see those big ugly Tin Can capacitors sprinkled over your system like warts. Transistors and resistors have shrunken in size, now its time for capacitors to become almost invisible as well.
I haven't thought of anything clever to put here, but then again most of you haven't either.
The first problem with a space elevator is digging the shaft. You can't go more than 6.4Mm deep for obvious reasons. And the nearest object, the moon, is nearly 400Mm away. This means you'd need at least 63 segments to your piston, and probably more. And have you ever been near even a normal, two or three-floor building lift when a hose failed? Trust me, that's scary enough.
... And thus the comments about the mfg. process 'catching up'. I think we already don't use Li-Ion AA's and AAA's because they're cost-prohibitive, and the packaging is wasteful of space. I already wince at paying about US$2.50 per individual AAA for NiMH. But this technology promises features I think are worth paying for, just like having Li-Ion and Li-Polymer batteries in your cellphone, mp3 player, and PDA right now. Imagine when the battery for your cellphone or iPod is long-lived enough to be printed onto the circuit board and never replaced, and it can receive a charge in only a few seconds. If this is done properly, it'll eventually be the end of removable cells altogether.
This even opens up a lot of integration possibilities that just weren't there before, like peripherals that bring their own capacitor bank in to boost the system's capacity. Everything with a PCB can now cache its power, without all the bulk of a traditional battery. Imagine expansion cards that can carry the power needed for I/O (Wireless, Flash Memory, whatever) and charge with the system. You could even use the memory expansion slot as an auxiliary battery, like on some laptops how the optical drive can be replaced with another battery.
Take this with System-On-Package designs like were just recently discussed here, and we may get some really small electronics in our lifetime. You could even reduce capacity to save space -- I wouldn't mind charging my cellphone almost every night if it only took a few seconds.
True science means that when you re-evaluate the evidence, you re-evaluate your faith.
I've got a small scar on my right index fingertip from just such a mishap. Back in the 70s when I was in grade school, I had several of the Radio Shack n-in-1 electronics kits. I built some circuit or other and used a NiCad from Dad's calculator to power it. Since I didn't have a battery holder that would accommodate the NiCad, I used my fingers to hold the wires onto the battery. Said circuit had a short in it and the wire got really hot, really fast. The resulting burn was painless and bloodless, but the scar is still there 30 years later.
I think this article is crap because it does not address that question. Who wants a cap that can store a lot of energy if the voltage decays from 120 volts to 3 before all the power is used? Capacitors are great for filters, but they will never replace laptop batteries.
Simon's Rock College
This story just confirms what we all knew to be true some 20 years ago...The flux capacitor is real!
I used a 1989 vintage computerized stage lighting control console used a big capacitor soldered to the back of the PCB to hold the settings in RAM while the unit was switched off. Typically, the capacitor could hold a show for about three to four weeks and every time it was switched on, the capcitor would recharge. It still had a "modern" 720k floppy disk just in case.
This is a boring sig
When I was in the Army, they taught us to use those 9V batteries with a fistful of fine steel wool to make fire.
Money for nothing, pix for free
I think also we might see a new type of 'tin whiskers' problem with this technology.
--
WHO ATE MY BREAKFAST PANTS?
This is really good news for the portable device market. Our portable devices can only get as small as the battteries needed to power them. While more renewable resources like ethenol seem attractive, the prospect of needing to purchase a cartridge is quite a turn off. Because these capacitors are significantly smaller, using them in portable devices will help us really break the barrier in energy storage.
We're all hypocrites. We all have hidden parts, it's the contrast between them that make us more a hypocrite than others
The thing is, one kg of petrol holds around 45MJ of energy. One kg of NiMH batteries hold around 0.25MJ, a factor of almost 200 less. A lead-acid battery holds half that. A normal capacitor holds 0.002 MJ/kg.
So, even to compare with lead-acid batteries in energy-storage this thing needs to be 50 times better than normal capacitors.
Recharging in seconds is fine, assuming you can build a sensible car that goes oh say 100 miles at the least between recharges, that's perfectly acceptable for most people. Same for cellphones; faster recharging is very nice. But only if you can still go for 2-3 days without recharging, and talk on the phone for atleast an hour or two before its empty.
A car that could only go 20 miles between recharges would not be a hit, not even if the recharge was done in a minute.
The fusion of capacitors and batteries was foreseen in the "River World" series
of novels. The device was called a "Bacapacitor", and it powered Sam Clemens
riverboat in the novel. The bacapacitor was charged from the "grail stones"
which flashed once a day to delivery food and supplies to the people living
in River World.
A rustic farmer is sitting on his porch. In the distance a "toom toom toom" noise can be heard. A pissed off look crosses the farmer's face as he reaches for his shotgun. He opens the breach of the gun and inserts shells that look distinctly like Energizer batteries. As he looks out over his cornfield, a pair of white ears can be seen serenely sliding above one of the rows. He takes aim and then bolts of lightning lash out of the shotgun towards the stately sliding ears. Drumsticks, drumpieces, and exploded bits of Energizer bunny fly everywhere. A smoking pair of sunglasses lands right at the farmer's feet.
"I jes hate it when rabbits get in ma corn."
Well now that made me think. What would be the incentive for companies to sell these bateries? Once you buy it, you never buy from them again because it lasts near forever. Sales would be good in the begining and then drop sharply once everyone has 'em.
Life is rarely fair. Cherish the moments when there is a right answer.
Everyone knows that, in the future, computers will rule the world and those computers will use humans for batteries.
Duh. Not capacitors! Stupid MIT!
The thing that really defines how useful a capacitor is the leakage current. This is the rate at which the stored charge slowly reduces over time even when no current is being extracted. For a perfect capacitor you need a material with infinite resistance to separate the plates, which I don't think is solved by using nanotubes.
Wow, what a great idea.
Now if only we could combine this with crystal power cells!
http://www.americanantigravity.com/hutchison.html
They have been using this concept in better watches for a long time now. Ones that charge via solar and ones that use the motion of your body to charge them. This is just moving up to the next level.
The "boom" would be cool. :-)
However, there is now a lot of academic and business interest in them as they are ideal for a wide range of modern applications. Devices like UPS's and power smoothers still run on lead acid batteries, which are bulky, contain corrosives and are prone to unexpected failure (at least mine seems to be). There is also a big push from the electric vehicle crowd. Note though that they are unlikely to form the primary power source for an electric vehicle (they still have poor energy density compared to chemical technologies), but are extremely attractive for both initial power-up (i.e. heating a fuel cell to running temperature) and for sensible implementation of regenerative braking - charge the supercap when you brake, use the energy for short term bursts (driving up a hill, overtaking etc).
You don't have to store high voltage in it, if you have a really huge area and microscopic distance, you can get a lot of energy with moderatevoltage. And if they get nanotube tansistors working they could use huge arrays of these nano caps and shunt them in in sequence digitally.
sudo ergo sum
I think we should all get bars of copper and zinc medically inserted into our stomachs. I guess we might need a friend or two if we wanted to run those latest high powered processors.
Hobby Robotics
People are already paying that much for rechargeable set-ups. I use it for my Digital camera and my wireless video game controller. Theyre great, when they go dead i just stick em in the charger for an hour then Im back off to save the universe.
At the very beginnings of electricity, it was stored in Leiden Jars, a form of capacitor. In the 1930's, the accumulator, a form of capacitor, was sometimes used to power early radios. Apparently, you used to carry these back to the shop to have them charged up.
The strenght of a capacitor explosion wont be any bigger just because it will have a larger charge. The explosion is not caused by its energy directly, its caused because of the expansion of its components breaking its wrap. No matter how many KW its charged, a 12V capacitor will never give more than a 12V tension, so its current will be limited by any resistance it finds, you can touch it with your hand and it wont hurt you more than a car 12V battery.
Impale a sausage on two nails, connect to a 9V battery. Just a few seconds, and it's cooked.
I was working desktop support for a large company that used HP machines. We had a batch of machines that acted very oddly, right from the start. NT Workstation (this was 1998-9) thought it was the year 1701. Telnet would not work. All sorts of weird things.
Turns out that HP had decided to use a capacitor instead of a battery to provide power to the CMOS BIOS. The units had been imaged by a contractor, then they set on a shelf for about 3 months before they got shipped to us for provisioning. The capacitors had lost their charge in that time, so the BIOS lost its settings. I don't know why this impacted NT so hard, but it did, and we had to send the whole lot back.
If you can't beat them, embrace and extend them.
This is why the batteries will cost like $200 for a four pack of AA's.
However, they'll still sell like hotcakes, because of the other characteristics, such as very rapid discharge, like the capacitor used in photo flash units, and the ability to work well in the cold.
All the technology in the world won't hide your lack of vision, talent, or understanding.
Ah but if you didn't have to replace those AAA's every couple of weeks/months then $20 would be cheap!
Women don't want to hear what you think. Women want to hear what they think, in a deeper voice.
i am really hoping that battery replacements, which we hear about all the time, will actually start coming to market, and actually make it past the researcher's desk. i think americans are willing to pay a premium for long lasting power, companies just have to finally make it available!
WTF? Charge isn't measured in kW. It's measured in Coulombs, and the stored energy in Joules (or kJ) would be the important thing. No idea what 12 V of "tension" means. And saying something won't hurt you more than a car battery leaves a lot of room for dead/burned people (ask anyone who's been using a wrench on the + battery terminal when the end happens to hit a grounded part of the car - nice light show, and it's a good way to remove small chunks of metal from the wrench)
Then do what is done with laptops/cellphones etc. Make different "form factors" so that batteries aren't interchangeable, and when you get a new model cell phone, the company gets to sell you a new battery.
See? They do this already!...
Karnal
The promise of replacing your computer battery with a capacitor that recharges in a few seconds probably can't happen all that time soon.
Some math to back this up: My work laptop, a Dell Latitude D610, has a 53 WHr battery. My home laptop, an Apple 12" Powerbook, has a 46 WHr battery. These aren't huge laptops, mind, and battery capacity is only on the rise as consumers demand more.
Let's use the Dell example, 53 WHr. Change hours to seconds, that's 53 * 3600 = 190,800 Watt-seconds (more usually known as Joules). 191 kJ - that's a fair bit of electrical energy to store, either in battery or in capacitor form. Let's ignore losses that occur in the charger and energy storage device - assume everything is 100% efficient for a moment.
What if we wanted to charge up that 191 kJ capacitor in, say, 10 seconds. That would require a 191 kJ / 10 s = 19.1 kW power supply. Hmmmm, don't think we'll be seeing one of those in a laptop bag anytime soon.
Laptop batteries are a particularly high-energy example, but it illustrates the kind of power increases you'd need to accommodate if instead of charging in hours, you charged in seconds. If you had a battery that used to charge in, say, one hour (cellphone, PDA, whatever), and you instead wanted to charge it in (again, for example) 10 seconds, the charging power supply would need to put out 360x more power. Even to charge it in a minute would require a 60-fold increase in power. That'd be an amazing and fascinating power electronics problem to consider - how to make such charging devices as compact as today's.
"These nanotubes, OTOH look awfully easy to break."
Isn't the space-elevator being made from these bad-boys?
Imagine refulling your car by simply stopping at the traffic lights. A swipe system like the toll roads handles payment, and your off again. It would not be hard to have a recharge every 50 - 100km on the highway if they aren't manned. Just a drive though pitstop - and your back on your way.
Who cares if electric cars don't have huge range if recharge stations are everywhere. And if your a "but I like to spend 4 days driving in the wilderness", then you take extra storage... just like you do with petrol.
Oh,... and it would not be hard to fix the complaint about exploding capacitors... Seal them in plastic so there water tight. Only two wires in/out... A very small amount of circuitry would allow high current in for recharging, and have a current limiter on the way out. Not crush proof, but certainly water/short circuit/toddler proof.
Ultracapacitors have been around for a while. http://en.wikipedia.org/wiki/Ultracapacitors They are commercially available -- manufactured by a company in San Diego called Maxwell Technologies. I believe there is a company in Reno making some as well.
What do you mean, Li-Ion AA[A] are cost prohibitive? They cost $3.59 and $2.99, respectively, on, say, batteryspace.com. And each has more than double the voltage of a NiMH cell.
Tsunami -- You can't bring a good wave down!
MOD PARENT UP INFORMATIVE
That's one proposal, but chances are that instead of using individual, free-standing nanotubes a few micrometers in length secured only at one end, they'll weave millions of somewhat longer ones together into cables that will be under tension.
This is not my sandwich.
You wouldn't sell this technology to consumers, you'd sell it to manufacturers. They will always be creating new gadgets that need power sources. All the manufacturers will of course demand that the format is proprietary to their device so that it is not easily replaceable without further purchases from them.
"If I were bound by all laws everywhere I'm sure I would have committed a capital crime somewhere."
...less [time] if you use a dedicated high-current circuit...
There's no reason why the charger/base station unit couldn't load up an internal capacitor over a longer period of time and then rapidly dump that energy into a portable device in a few seconds. That give you the rapid recharge times without using a clothes-dryer style power plug or browning out your lights whenever you recharged your cellphone (or, worse yet, laptop).
I think the biggest obstacle to rapid charging will be the physical connectors: nobody wants a 3x8 cm charging connector on an iPod or Razor! (But a few of minutes charge time instead of a few seconds is no big deal: you plug in your cellphone, brush your teeth, and by the time your're done it's fully charged and ready to go).
Mr president, I need such a battery in all my cool gadgets right now !
Please allow me to torture the hell of those MIT scientists and all their family to speed research up so i can save the world from $FATAL_MENACE by throwing my numerous cellphones at the face of evil terrorists.
Please hurry your ass up, i've only got 40 minuts left and 20 of those are commercials.
Your sincerely,
Jack Bauer.
Caps charge fast, but they can also discharge fast.
Batteries have an inherent resistance that stops them discharging all at once. Without a resistor in the circuit, caps can discharge fast enough to be a hazard.
Depending on your application, this can be a good or bad thing. I haven't heard of any pocket flash cameras shorting out and hurting someone (unless modified it to be a "ghetto taser"), but larger devices like laptops could be another matter.
I see people saying this should bring the Electric Vehicle closer etc. This may be true, I don't know. But what I do know is that charging in 5 min would be hard to do. If I remember correctly, the EV1 had about 20kWh onboard. Charging that in 5 mins would mean a charging energy of about 240kW (not counting losses). That's serious energy.
Even charging, say, a mobile phone battery pack would be a challenge. Say, a 4Wh energy content. That's nearly 50W going in for 5 mins. That's going develop some heat.
Maybe a battery-swap construction would be more viable.
I already pay $20 for a pack of AAA NiMH batteries that last me for years.
Find environmentally and socially responsible products on http://buy-right.net
Go find yourself a 12V high-amperage battery. I recommend a deep-cycle marine battery.
Grab the electrodes.
Write back.
- Michael T. Babcock (Yes, I blog)
The page in your sig is down.
The guy has a poster discussing uses such as electric car batteries, so I would say no. One part that bugged me in the "poster" is the energy density. A value of 60Wh/kg (is this gravimetric charge density?) is less than lead-acid. The power density is a whole lot higher at 100kW/kg, would someone care to explain the difference between the two?
What if, the capattery itself was sealed watertight, so just the wires came out... then somewhere in the phone we could put some... thing. And this thing could kind of make some sort of break in the circuit when too much current went through it... some sort of "circuit breaker" if you will.... And after you get the phone out, well you could dry it off and then reset this thing so that the circuit was restored. Nah, if such an easy solution for dealing with high current discharges was so easy, someone would already have thought of it and it'd be in every home and office by now. Forget I mentioned it. Crazy idea.
Introducing the new Occam Fusion! Now with sqrt(-1) fewer blades!
double the voltage? or double the capacity (2xmAH)?
I think we already don't use Li-Ion AA's and AAA's because they're cost-prohibitive
The bigger problem is cell voltage. A Li-Ion cell puts out about twice the voltage of an alkaline or NiMH cell. A lot of electronic devices cannot handle the higher cell voltage. This is the main reason you do not see Li-Ion cell in conventional button-top AA format at Wal-Mart.
I guess you are not aware of the little firebombs called Lithium-Polymer batteries you hold up to your head every day in your cell phone.
Overcharge a Li-Poly or Li-Ion battery and they will literally explode and burn.
Drain them to low and they won't ever charge up again.
Thanks to smart chargers and current limiting circuts in the packs themselves they are safe for every day use.
Here's a Video of a Li-Poly pack being over charged.
Lithium Poly Fire WMV
If you think it's expensive to hire a professional to do the job, wait until you hire an amateur. --Red Adair
Yes! Encase it in titanium! It's cheap now!
Yesterday was the time to do it right. Are we having a REVOLUTION yet?
OK, sure, theoretically you can recharge these things in seconds... but to do so will require moving scary amounts of current around.
Right now, those NiMH "fast recharge" batteries you see at the store take about an amp to recharge 4 2500mAh AAs in about an hour. So, what if you want to charge them in, say a minute? That's about 60 amps of current.
And there's the problem: your average houshold circuit tops out at probably 15 amps; Hell, even your air conditioner or electric stove circuit probably doesn't provide more than 30 amps. So the fastest you could charge those new-fangled "battacitors" is four minutes *if* there's nothing else on the circuit; or more realistically, 10-15 minutes *and* all the lights in your house dim while they're charging.
Circuits were never my thing. Maybe I'm missing something here. I'm sure you EE types will correct me...
Learn from the mistakes of others. You won't live long enough to make them all yourself.
Double the voltage, with a little less than half the mAh rating of a same size NiMH cell. Therefore, it provides a little less energy capacity. (mAh gives Coulombs, not Joules).
On the plus side, its discharge curve is more abrupt, so it tends to be better for powering electronics. Further, it provides many more charge cycles, has no memory effect, and has great shelf life (won't discharge as quickly as NiMH if not used).
Tsunami -- You can't bring a good wave down!
I'm thinking this might be a great improvement in terms of the battery life of mobile probucts... On the other hand it might be very sensitive to mechanical impact. That would probably end up reducing the battery power anyway. Leading to more expensive waste...
Blind are we who do not know that we are blind. The world has been boring ever since I got here.
Well, consider that a CRT (TV Picture tube) is among other things, a giant fricken capacitor. And it can hold a charge of 18-25 kilovolts for many years. (Go ask anyone who worked on those puppies back in the day when there were television repair shops about the precautions they would take when handling a old picture tube.)
Now, consider that the recharge time for capacitors can be measured in seconds or less - after all all you need to do is stuff electricty in there for storage. Trying to fully charge a battery in seconds will result in an explosion because you are not storing electricity - you are reversing the chemical reaction that the battery uses to provide electrons.
Here is a better question:
Assuming that 50% of the volume of the nanotube capacitor will be taken up with voltage regulators etc. , then what would be the capacity in mAH of a direct replacement for an "AA" battery?
You either believe in rational thought or you don't
I noticed my digital camera getting warm one time and thought to check the batteries. I removed them and almost burned my hand off. They were way too hot to touch. I tossed them out into the gravel driveway for safety, knowing full well that if they felt like it, they'd make a fun light show out of my forearm.
Another $15 pair of NiMH's bites the dust.
- Michael T. Babcock (Yes, I blog)
Which also means that the first company to sell these will make the most money. There's going to be a rush.
Now I'm getting a little OT but I dislike the Energizer Bunny commercials and thought of a cool commercial. We could see the Energizer Bunny marching down Death Row. They strap him into the electric chair powered by a big Duracell battery and zap him to death. :-)
"A government is a body of people, usually notably ungoverned." - Shepard Book Quoting Malcolm Reynolds
I can imagine portable arc welder powered by these things. And really powerful power tools, not that weak crap we have today.
I'm not insane. My mother had me tested.
Think of all the energy we could muster by capturing all the hot air coming out of MIT.
Yes I know they produce some very nice tech, but they also seem to speculate and use their good name in a loose manner lately.
Autonomous Retard -- Is your camp safe? UnsafeCamp.com
I'm pretty sure all AAA, AA, C, and D batteries provide roughly the same voltage.
No. Their AAA cell provides 3.7V (that's the Li-Ion cell voltage dictated by physics) and 350 mAh. Compare this to a 1.2V NiMH cell with 850mAh.
Li-Ion cells
NiMH cells
What Li-Ion might improve on is mAh (read: how long they last before needing to be recharged)
Not quite. mAh specifies the charge, not energy; a battery than can supply 100mA for an hour at 100V has much more energy than the one at 3V. With the above two cells, the Li-Ion stores 4.6kJ, which is more than the NiMH with 3.6kJ.
Tsunami -- You can't bring a good wave down!
The xbox's cap doesn't last for days. I learned that back in the days when I had the font exploit running on it. It caused the xbox to fail to boot if it forgot the time. I could never leave it unplugged for more than about 6 hours.
this would be quite a break trough.
The current problem with electricity is we cann't store it well.
Most storage solution cost a lot of energy.
A wind turbine a solar power plate it al depends on the wheater and vary in production.
While on the other side demands also vary. Having a power saving plant based on this technology would be great.
Having something which can be charged a lot times without loose of lots of energy like current bateries is a dream of anyone who manages a large electric grid.
would have a proprietary battery that would only fit into Sony cars :-)
Seriously, compatibility has always struck me as the weak point of the battery-swap idea. You would have to get all the car manufacturers in the world to agree to a standard size, shape, connection, and electric properties. This would prevent Ford (for instance) from saying "The new Escape has a battery that lasts four times longer than the competition" and would discourage battery improvements, because when you dropped your "improved" battery at the station, who is to say if you'd get the same "improved" type in exchange?
Indeed, there's a similar problem for recharging battery-powered cars, as you'd have to have standard charging paddles. But at least you could upgrade your batteries (or the charging equipment) and keep the old charging system.
The big benefit that gas currently has (aside from high energy density) is it's a physical substance that's easily used by "common" physical interfaces. A BMW, Ford, and Renault may all have different length/shape/diameter filling tubes, but as long as it's "close enough" you can get the end of the pump nozzle into the hole.
Interested in a Flash-based MAME front end? Visit mame.danzbb.com
Theres nothing to explode when its a capacitor. If it gets hot enough fast enough, it will melt the plastic casing, then melt any metal in the vicinity if it hasn't run out of heat. I imagine you could make a mess with these, but they aren't a lot worse than chemical batteries. You wouldn't want either to be in your pocket while in a hard collision.
"And we have seen and do testify that the Father sent the Son to be the Savior of the World"
1 John 4:14
The recharge time problem was solved with safe, high voltage recharging technology which has since been withdrawn from the market. You could get an 80% charge in five minutes, which would then take you 100 miles (real miles - unlike gas burners, EVs don't burn fuel at stop lights) making range comparable to 1960s compact cars. You will be sued if you try to deploy the technology today; and GM (the patent owners) have been forcing California businesses to rip their installations out.
Every EV1 ever built was immediately snapped up and thousands of people were left waiting in line when GM successfully subverted the will of the people of California and killed the vehicle. They only built 800, despite their promises, and they have spent more $$ on preventing EV production and distribution than they ever spent building them (most of their development costs were defrayed by Clinton & Gore's EV subsidies).
Who Killed the Eletric Car(Warning: hideous flash and cookie onslaught)
That's why you're in IT and not marketing.
Gamingmuseum.com: Give your 3D accelerator a rest.
after half the charge is gone out of a capacitor, you're only going to have half the voltage. So what are we going to do about powering a dc device that needs constant input voltage? Go dc to ac to dc to get constant voltage, very wasteful of energy do to conversion inefficiencies. Put a voltage regulator on it and lose trememdous amounts of energy to heat (and also have the device shut off as the input voltage falls too close to the desired output)? any practical substitution of capacitor for battery is going to have this problem of being extremely wasteful, never mind the much lower energy density.
"...making blinded capacitos out of economics"
So there is a use for economics!
Optima has a patent on unrolling the core and creating a spiral.If they are able to use this, then they would have quite the batteries.
I prefer the "u" in honour as it seems to be missing these days.
You are wrong. The amperage is limited by my body resistance and the battery tension. 12V dont hurt anyone.
Typically, capacitors discharge like this and batteries like this.
That means the voltage of batteries usually behaves more constant than that of capacitors when discharging. This surely has it's repercussions through the power lost at the power management units.
I hadn't the slightest objection to his spending his time planning massacres for the bourgeoisie... (P.G. Wodehouse)
You are trying to do with electricity again what is wrong in America (and the world for that matter); we depend on one technology; oil. A better solution is to create an electric car with a small bank of batteries and a bay; In that bay, you could order it with batteries (exactly what you want, but good for cities and 2'nd car), a gas/diesel/ethanol based generator that creates at least a portion of the electricity needed, or in the future a fuel cell.
What is needed is flexability in our system.
I prefer the "u" in honour as it seems to be missing these days.
I wouldn't mind charging my cellphone almost every night if it only took a few seconds.
Exactly how little sleep are you getting that you can't charge your cellphone every night? One of the last things I do before I go to bed is plug my cell phone in, and one of the last things I do before leaving for work is unplug my cellphone. That gives between 5 and 9 hours to charge, and most phones only take a few hours. So where's the problem?
Now, if it only took a few minutes to charge, I'd want them to throw all kinds of features on there that would suck up power (if used). Recharging a few minutes a day in even a busy schedule is nothing - just plug it into your car while you're heading to work.
Sure I'm paranoid, but am I paranoid enough?
Chemical battery manufacturers have built their business around highly-specialized component manufacturers. There are the case manufacturers. They won't be needed anymore, since I seriously doubt anyone would stick a capacitor in a metal case. Different companies make the chemicals, the internal parts, the plastic label, the glue, and the packaging. The only one that will still be relevant is the packaging maker.
Great idea, though. Rechargeable batteries turned out to be A LOT more expensive than the alkaline ones (they fail to hold a charge long before they catch up with A/h provided), and are more dangerous to the environment and consumers. I can buy 240 batteries at the dollar store for the cost of a NiMH charger.
He'd just take the opportunity to recharge. Defeats the purpose.
The ultra cap I looked up had an energy density of about 4 wh/kg. Given that the battery in my car has about 1200 watt hours, I could replace it with an ultra cap weighing 300 kg. It sounds like the ultra cap is an order of magnitude worse than lead acid.
You misunderstand basic physics.
0 65.Ph.r.html
http://www.madsci.org/posts/archives/feb98/887061
- Michael T. Babcock (Yes, I blog)
No one is going to pay $20 for a pack of AAAs that you can get for $4 and just have to replace in six months.
Personally, I have found myself buying those new 5 year light bulbs that cost 5 times as much as a normal light bulb because I was just sick and tired of getting on a ladder every time the hall way light went out.
Given the choice of having to constantly do something (like change light bulbs, batteries, etc) and buying something once and then forgetting about it, people will eventually go with the route that requires them to do less labor.
Now if I could get one of those new LED light bulbs and I'll never have to put forth physical effort in my house ever again.
"I am the king of the Romans, and am superior to rules of grammar!"
-Sigismund, Holy Roman Emperor (1368-1437)
"A little bit of caustic goo" coming out when you mistreat batteries? Do a web search for lithium polymer (lipo) batteries and safety. Find some video. (hint the charging instructions say to use a fire proof box) NiMh cells will also 'violently rupture' (aka explode) and lead acid ones can leak hydrogen...
Xbox.
It uses a supercap for the real time clock. Each time you turn it on, it's good for a couple weeks. Leave it too long, and it loses the time.
http://lkml.org/lkml/2005/8/20/95
You're close. I just scratched this on an envelope, so bear with me. It may not be 100% correct.
4 x 2500mAh = 10,000mAh
1.5V per cell -> 15,000mWh = 15Wh = 54,000 Joules
To charge the batteries in 1 min:
54,000 Joules / 60 seconds = 900J/s = 900W
That's not that bad at all. It's about the current draw of a small microwave.
You are wrong,at least if you use efficient switching power supply.
Charging 1.2V/2500mAh cell in 1 minute would theoretically take current of 60x2.5A=150A, but at some 1.5V that would mean power of cca 230W. At 230V of mains voltage your current draw would be cca 1A. High output current doesn't neccesarily mean high input current.
If things were working as you say, at some 100A feeding CPU in your machine, your electricity bills would be _VERY_ interesting...
I'll take the moment to speak like a pyromaniac (electromaniac?) and say that the safety and durability issues just maen it's easier to visualize this being weaponized.
So what difference does the battery's amperage make? Did you mean internal resistance?
Does dry-skin resistance (quite high) not come into play at all?
Please explain.
current = tension / resistance If you put a voltimeter in a short-circuited/touched van de graff generator it will show you it loses its tension when it has load. The famous "its the current that kills" is a quite empty catch-phrase, since current and tension are directly proportional, and your body resistance is fixed. I already touched the outlet at 220V and did didnt kill me. I can hardly imagine what would be the maximum current that power station is capable of throwing at me, but its limited by my body resistance.
carbon areogel capacitors? I remember reading somewhere that these where going to be the new batteries because of their super high surface areas.
Si vis pacem, para bellum! For evil to succeed good men need only do nothing!
This article is a good example why science news is poorly reported. Critical facts omitted from the article:
Ratios between capaciter and equivelent battery with the same energy stored
- Volume ratio
- Weight ratio
- Recharge time ratio
- Estimated number of recharges during its lifetime
The lack of basic facts in the article should be corrected.
Given these densities, could you build one suitable for a house? What would that cost? It seems ideal to be recharged by intermittant power sources such as wind and solar.
"We reject as false the choice between our safety and our ideals." --The American President (20.1.2009)
I have a Seiko kinetic watch. It is powered by a capacitator. The movement of my arm is enough to charge it. Fully charged it should work 4 to 6 months when lying still. More expensive watches by Seiko can last for 4 years I believe.
Theres nothing to explode when its a capacitor.
:)
Reminds me of my electronics class some years ago. Working in teams of two, we had hooked up a small circuit to an oscilloscope to watch how the signal was affected by the circuit.
After some time, I hear from the back of the room, with a nervous tone: "it's getting bigger, it's getting bigger!" followed promptly by "turn it off turn it off!", to which the other guy replied "but it IS off!". Next there was a loud crack, like a big firecracker had gone off. I turn around and see the two guys sitting there all frozen up and confused, covered in fine fur along with the table.
So yeah, cap's can be fun
Many dc-dc converters can be 80-95% efficient over a wide range of voltages.
Neat trick. I'll have to remember that.
-William Shatner can be neither created nor destroyed.
Nanotubes are strong like you say, but they're also brittle.
I take it you've never heard of fuses and circuit breakers? Look them up. They're quite useful for providing protection from short circuits.
-scsg
>I assume there must be some inherent difficulty in making them with both a large capacitance and high-voltage rating
Other things being equal, the way to get a large capacitance is to get the plates, or electrolytes, or whatever as close as possible. Which is ofcourse antithetical to using high voltage. Current ultracapacitors have their active elements just a few molecules apart.
I was going to post a similar thing, but from the other side.
I've shorted my RC NiCds before, and they won't vaporize a screwdriver. They do puff up, get very hot and leak, but not damage the screwdriver. And NiCds have very low internal resistance, 10X lower than a NiMH, which is more than 10X lower than LIon.
You've created an incorrect comparison. A battery will cause a violent release of energy like a capacitor, but the release is so much smaller compared to a capacitor that you need to use a very big battery to see results.
You can use a capacitor that is less than 1/10th the size of that battery (and thus has less than 1/1000th the energy storage of it) and put a screwdriver across it and get the same effect as that battery.
Note you cannot put a small resistor in the package to fix this problem. Small resistors have small power dissapation characteristics. If you put in a small value resistor, it will present little resistance and as such the currents in a short situation will be very high. Let's say you have a 4V battery (like a LIon) and you want to keep the current down to 10A. That means you have a 0.4ohm resistor. Now, when you short it, it will dissipate 4W across the resistor. That means your resistor will have to be something over a cubic inch in size. You probably want a smaller value resistor so as to waste less power but then your power dissipation goes up! An active circuit that cuts out on over current might be a better idea. It could have lower resistance and still not have to be large since it will open the circuit rapidly.
Car battery cases are very strong, it's just that car batteries are very heavy. A metal case wouldn't perform any better on something that heavy. The difference is when a car battery cracks open, the only thing that comes out is chemical energy. You end up with ionized electrolyte at your feet. If you impact a capacitor and the plates touch, you're gonna have a quite different result.
I really don't see this being a big player. Supercaps have been around for a while. They're good for some things, and not for others. Oddly, they aren't as good as batteries due to their high resistance (more than a LIon, IIRC). Also, they can't hold a charge for long enough to be useful as a battery in many applications. How'd you like to come back from a 2 week vacation and find your car battery dead?
http://lkml.org/lkml/2005/8/20/95
Uhmm, you must be thinking of diamonds, nanotubes arn't known particularly for brittleness to my knowledge.
Electric car manufacturers decide on a few standard battery packs. You drive up to the battery station, the attendent ejects the low battery, pops in a charged up battery, and throws the low one on the charger. Doesn't really matter what the charge time is.
I was talking about the batteries for portable electronic devices, not car batteries.
And I've witnessed the explosion of a truck battery before. What explodes is the hydrogen produced during the charging process. Sulfuric acid gets sprayed everywhere. Way the hell fun.
Capacitors surely have the advantage of not doing that when they explode, but let's just look at the rate of discharge and the stored energy. Example: My camera uses four 2800mAh AA-size batteries. That's 40,320 coulombs, which at 6 volts comes to 6.7 kilofarads or 242 kilojoules. A capacitor storing that can discharge it instantly. An 80 Ah car battery stores about 3.5 megajoules. Discharging that much energy in 5 milliseconds (a number I pulled out of my ass (making it exactly the same as every other number here)) comes to 691 megawatts.
Hook two of those babies to a flux capacitor and Dr. Emmett Brown can send you back in time. Do yourself a favor: instead of taking your hot teen mom to the Enchantment Under the Sea dance, sit down and write a Kurosawa-in-space knockoff called Star Wars. When it's time for the second sequel, see if you can do it with no fucking Ewoks. You'll be glad you did.
This is not my sandwich.
In radio controlled stuff these days, Lithium Polymer batteries are now widely used because of their high capacity and high amperage abilities. But they are highly volatile. They can explode sometimes, especially when charged incorrectly, or if they are shorted out. Search google for "lipo fire" and you'll find some pretty interesting pyrotechnic videos. Also google video has a few. But from what I understand capacitors are more dangerous than batteries for reasons other than fires and explosions. The voltage that can come off of a cap can kill a person. In the case of an auto accident, chemical fires can probably be dealt with by emergency personel. But having an accidental discharge of a large capacitor could kill emergency responders as well as the people trapped in such an auto.
Please cite (not just mention) a repetition of Franklin's kite experiment according to Franklin's published methodology.
The page you linked is a long discussion, without rigor or evidence, of circumstantial implications for Franklin's story's plausibility, boiling down to "he wouldn't risk his scientific or resulting political credibility on such a hoax". When his scientific reputation was being stolen, preempted by European plagiarists, the target of the hoax, which would have protected his reputation.
The very page you linked has a response citing analysis of repetition attempts, which electrocuted the experimenter following Franklin's methodology, and the relevant differences in methodology (grounding) that protected the "successful" experimenters.
The always murky field of historical inference yields to the facts of scientific history. If you want charges of sensationalism to stick, you should look at the easily-available counterarguments to the hype you're pushing, which are dry facts.
--
make install -not war
anyone say me wtf is that?:? lang=English
http://www.esma-cap.com/Products/Capacitor_cells/
super capacitors already here %)
Agreed. :-P
Part of my problem is that my cellphone's charger is on my bedside outlet, connected to a switch which my wife often turns off when she comes to bed. I don't find out until the next morning that it sat there most of the night not charging, but if I leave it in another room I will sometimes miss customer calls in the mornings. The real point I wanted to make is that I'll be glad to charge it more often, as long as it spends less time suckling at the wallbound teat.
True science means that when you re-evaluate the evidence, you re-evaluate your faith.
i) Your body is not the only component of the circuit, and hence does not provide all the resistance. Some is provided by the battery itself. ii) The current that a battery can produce varies immensely iii) The 220V alternating current of a mains electrical socket is not the same as the direct current of a battery.
The "internal resistance" of traditional alkaline batteries is fairly high, which is why you can "tongue test" a 9V brick and just feel a slightly uncomfortable tingle. The current being run across your tongue is low.
The internal resistance of a 12V lead-acid car battery is much lower, and it can produce a much higher current, because the internal components have a much higher surface area for the electrochemical reactions involved. You didn't think all that extra bulk went into providing an extra 3 volts, right? A car battery can provide you with severe burns, because it can spit enough current to start a car.
The internal surface area in a car battery is NOTHING compared to one of these babies though. The area is the key to how they would work. A nano-cap would be able to discharge itself just as quickly as it charged, which means, say, the discharge from a 1kWh unit would be a similar amount of energy to having 60 cups of boiling water poured on you simultaneously.
The reason a 220V jolt from an AC unit didn't kill you was because AC alternates 60 times a second. Just as soon as the charge has travelled a little distance one way, it wants to travel another. The current is thus basically nil - the major damaging effects from low-voltage AC current (yes, for AC, 220V is low) are more to do with the disruption of neuroelectrical processes.
A van der Graaf generator has huge voltage, but very little current. It is, in effect, another capacitor, but the charge it stores is very low. These are specifically designed for the charge to be high, like batteries, with the added wrinkle of extremely low internal resistance.
or...
No, the power company couldn't possibly throw enough at you. Ignore the "danger of death" signs and go suck a substation.
I think we already don't use Li-Ion AA's and AAA's because they're cost-prohibitive, and the packaging is wasteful of space. I already wince at paying about US$2.50 per individual AAA for NiMH.
That cost savings for alkaline AAA over Li-Ion AAA does not include the disposal/recycling cost, which is significant, yet consumers don't pay it at the cash register. It's a hidden/deferred cost. I'm not discounting the benefits that this new capacitor technology could bring (if it works) - but the benefits of rechargables are crippled, economically, by the cost-deferrment of standard AAA's.
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
Never shorted a car battery with a screwdriver, eh?
You get a violent electrrical arc and (quite possibly), an explosion, as well as all that acidic goo.
You could've hired me.
1.) Nothing never wears out. Ideally a part doesn't wear out in the system's lifetime, but even solid state components die eventually, even if it's from corroding away 10000 years from now.
2.) If a company picks up on the technology (or the MIT guy picks up some venture capital and develops it himself), they have a serious market advantage over traditional battery companies because they have a better product (hopefully). The other companies have to follow suit to remain competitive (patents allowing). The first guy has an interest in getting to market as fast as possible to gain market share before the competitors catch up.
3.) We will never have all of the capacitors we need. Selling them as replacements like batteries might be unlikely, but in the near term they could compete against rechargeables, and in the long term, new products will continue to need onboard power.
4.) The intially high demand would allow manufacturer's to quickly recoup their development and tooling costs by charging more early in production while avoiding the need to invest in extremely high manufacturing capacity. As price drops, they become financially feasible to a larger market.
5.) Waning sales from market saturation are just one more thing companies deal with on a regular basis. Compare these to another item that doesn't typically wear out: silverware. Everybody's got forks and spoons, but consumers still buy new sets.
I've seen a couple of these posts - this is not true.
I've shorted many NiCads from full charge to zero, using 16-gauge wire. I've never once seen an explosion - the battery's internal structure is very much like a capacitor, except with an electrolyte instead of an insulator between the plates. These plates are extremely efficient in conducting electricity - the battery does not heat rapidly enough nor to a high enough temperature to cause any such explosion (if there even is such a temperature). The reactants have a maximum rate at which they're react at - the low internal resistance serves to prevent heat buildup.
None of my R/C friends have ever reported exploding batteries - leakage, yes, shorting wires burning incandescently, yes, fires (not caused by the wires), no, explosions, definitely not. And we deal in the 40+ ampere range on a regular basis.
The above may not be true for NiMH and Lithium Ion batteries, I don't have much practical experience with those in high amperage and short-out situations. In fact, I believe Lithium Ion batteries either catch fire or explode if overcharged.
You capacitor people should spend some time researching coin shrinking, by the way.
About capacitors - I have a bag full of pieces of these things from explosions - little metal cans, torn apart, wadding from the insulator, bits of very thin metal... You want to make these in the kilo or megafarad range? The exploded ones I have are in the microfarad range! Capacitors aren't limited by chemical reactions as to how fast they can dump their stored charge! I'd like to see some serious safety laboratory testing for these before mass production begins!
When you put a voltimeter in a car battery, its internal resistance already reduced the tension on its terminals. So, that 12V has already taken that into account. The 220V in an AC outlet has also already taken into account everything you said. Its peak tension is HIGHER than 220V. It burn you with the same heat as 220V DC. AC is a bit safer because you feel its effets and react faster. So, go learn something before coming here and insulting me.
Why don't you try refuting the facts or logic of the grandparent? You have no idea who posted it. It could even have been an "MIT and Cambridge scientist" for all you know. From the tone of your post, I am guessing that you have neither the knowledge nor the experience to comment intelligently on the subject.
The article doesn't mention either the leakage current (which causes caps to self-discharge) or series resistance (which limits the current you can get out of them). Caps traditionally are much worse than batteries on both of these, but with recent NiMH's sacrificing leakage for capacity, they self-discharge much faster than they used to, so maybe these caps can win by batteries just getting worse enough fast enough! :-)
- ST
FWIW, the deep-cycle battery won't hurt him as much as a regular car one.
Car batteries are opimised for low internal resistance; providing energy at a high rate. They like to be kept pretty fully charged all the time, and their total capacity isn't that great, which is fine because they are going to provide that one quick jolt to start the engine, then get recharged by it.
Deep-cycle batteries are designed to provide power over a longer period; They're what you want if you are going to actually run stuff off the batteries. They have greater total capacity, and are more tolerant of actually getting significantly discharged, but with the trade off of not delivering quite so big a jolt all at once.
Either one will hurt you pretty good though.
You guys are forgetting another obvious application of extremely high density capacitors, weapons systems! Keychain tazers and bombs and being able to literally bust a cap in someone's ass. Discharge through a coil and have a car mounted railgun.
Someone please create a company, call it Flux, and start selling capacitors :)
Most thoughts on this are for portable items or even cars, but what about having ones designed for powering homes. Having something with a decent capacity that recharges quickly and at a constant rate in each house would be preferable to having hundreds of thousands of homes pulling power at constantly varrying levels. I live in California so I normally get to deal with the rolling blackouts durring the summer months due to people running their AC's too much, but something like this could spread the power draw evenly throughout the day, so extra power is being drawn from the capacitor durring the day while the AC is running, then recharged at night when power use slows down.
This might be able to also remedy the insane power bills from running items at "peak hours". I'm not sure what the cost or actual feasibility of something along these lines would be, but it could be alot better than things currently are. It could also serve as backup power incase of a blackout or brownout, possibly even have a backup mode where it just provides power to certian locations or outlets so some lights work and alarm clocks don't reset. I may be way off base here, as I'm not overly informed in EE but it seems possible.
i got the same scar on my finger from a paperclip and an old nicad camcorder battery. permently altered my fingerprint
Don't try the screwdriver trick suggested by this post's parent. You could get serious burns due to flying molten metal, and sunburn/blindness due to the UV light that is released. Seriously.
I'd envisioned the nanotube capacitor as using the inside and outside surfaces of the tubes as the "charge plates". That is, the inside of each tube might be negative, the outside positive, or vice versa. Thus, the walls of the nanotubes would themselves be the dielectric. The article seemed short on that sort of detail, though, so I'm just guessing.
Great men are almost always bad men--Lord Acton's Corollary
sure, for constant input applications, I've seen greater than 90% efficiencies for telco dc (-48 vcd) to gate logic level converters, but here we're talking about input voltage going linearly to less than 5% of original value if we don't want to leave any capacity charge/energy unwasted. I'm thinking a converter will be 80% efficicient over such a huge range.
hah, less-than sign removed as being html-ish, wrote less than 80%
Most battery powered electronic devices have a switching dc-dc convertor already because battery voltage is not contsant either.
The big advantage of fuel cells is that you can carry a bottle of meth around with you and recharge without being anywhere near an electrical outlet.
No sig today...
Fiddling with the electrodes in capacitors is not a new idea. Supercapacitors often use ultra porous carbon aerogel/activated carbon as an electrode material. The porous electrode is then immersed in an electrolyte which also acts as the other electrode. The gaps between the ions in the electrolyte and the surface of the aerogel are incredibly small, on the order of a few nanometers! Anyways, carbon aerogel is 90-98% pores. I doubt that any surface area gain over and above that of aerogel will be able to justify the increased cost... at least not in the near-term.
That said, capacitors probably will replace batteries. The most likely route for improvement is for tweaking the dielectric mechanism between the electrolyte-aerogel. Current supercapacitors have atrociously bad maximum voltage; they can only take ~2V before breaking down. Furthermore, the energy stored in a capacitor is proportional to the SQUARE of the voltage and only directly proportional to the area. In fact, these very high surface area electric double layer capacitors haven't been around that long. I think it is most plausible that a better cap will be realized by increasing the breakdown voltage, we already have insanely high surface area.
As an aside, the best attribute of a capacitor is its power. The quick discharge/charge is more than enough for virtually any application. Anyways, complaints about needing DC/DC convertors for these for vehicle applications are warrantless. You need to closely control the voltage supplied to the electric motor no matter what! Controlling the voltage is the electrical equivalent of your gearbox, only it can be made far more durable and is cheaper.
I dunno about unplugged. I'm just talking about switched off here. If you don't even switch on your Xbox for a couple weeks, it'll lose the time. At least on the model I have.
It might go even quicker if you unplug it, I never checked. Not that I've never unplugged my Xbox, just that I've never unplugged it for more than 15 mins and less than a few weeks.
http://lkml.org/lkml/2005/8/20/95
Capacitors will rarely replace batteries, because you need a much larger volume to store the same number of amp-hours.
Sure, when you fill your care you're moving 5MW of power. But there are severyal problems with your reasoning
- A filled car lasts days/weeks worth of driving. It's not like you need 5 MW of power / day. A fraction of that is all you'd use in a 24 hour period. With electric cars that can be recharged anywhere, including your house, you don't need to hold 5 MW of power all at once.
- That gasoline may contain 5 MW of power, but you don't get anywhere near 5 MW of power out of it. Even th emost efficient internal combustion engine sin cars only get about 40% of the potential energy of the gasoline into actual locomotive movement. There is a ton of wasted energy in heat and friction. Electric cars are much more efficient - there is less friction inside the motor (because of the very fact that it is electric), and there is ahrdly any loss due to heat. Because of these reduced requirements you can go further with a lower overall engery desnity in an electric car.
To put it simply, both you and the GP are wrong. The problem is not charge time, it is energy capacity. The reason electric cars are not taking off has nothing to do with how long it takes to "fill the tank", because who gives a shit how long it takes when i can "fill the tank" while I sleep at my own house? The problem is that with current battery technology, even a "full tank" will last you about a day at the most if you have a 1 hr commute - a real pain in the ass if you get unlucky and are stuck in traffic!
I don't know enough about this technology to know whether or not it can actually improve on current battery *capacity*, but that is what matters when it comes to a fully electric car. We need an electric car, whose battery bank can run it at 55-60 mph for 8-12 hours non-stop. Once you hit that threshold, it will become a useable piece of technology. It doesn't matter if once drained it takes 6-8 hours to charge, cause you'll be sleeping during that time anyways.
The real stats for this technology are about 187MJ and 520kW for the 336 lb./ 153 Kg array, => 340Wh/Kg and about 3.4 kW/Kg.
About half-way down the page I found this recent patent which is quite revealing:
"Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery?" - Patrick Henry
Amp-hours for batteries is a 20 hour rating. Thus, a 2500mAh battery outputs 2.5Ah / 20 = 0.125 Amps. Times 1.2 V = 0.15 Watts.
.15W * 20 = 3W. Recharging in a minute would take 180 W. Four batteries in a minute would be 720 W. The maximum power of a 15A circuit seems to be 15A*120V = 1800 W.
That's discharge over 20 hours. Recharging in an hour would take
So I agree with the guy who said it would run like a microwave.
After all, whereas a battery stores energy in chemicals, a capacitor stores energy in a magnetic field.
Will this disrupt any nearby devices?
Hmm... my HP 48G calculator has been running on the same 3 AAAs since December... and before that, the AAAs were in a LED flashlight.
Sounds pretty good for alkaline bateries. (But, then again, HP had some genuis engineers before they killed their calculator division.)
--Nick
But do you get messages when an AC replies to your posts?
"I'f this really is safer for the environment" Since the charging process do not rely on any chemical reaction, these capacitors should last longer and people won't dispose of them as often as with regular batteries. Maybe not before disposing of the device itself.
Saw this mention
and I imagined the followingKen: (coming in during a snow storm) "Barbie honey, I've had a serious accident .... really serious for us"
Barbie: (concerned) "Wha..What happened, honey ?"
Ken: "I slipped and fell on the ice !"
Barbie: (thinks, "Is that all?") "Here, let me ....."
Ken: "No, please, no"
Barbie: (shocked but beginning to notice the peculiar smell and the burn marks on Ken's trousers) "???????????"
Ken: "I had my key-chain in my trouser pocket when I fell, and my key-chain tazer ... well ... "(falls to the floor in a dead faint)
Clauswitz said it, and it is forever true, "Begin by looking after your own ass!"
How many beans make five, anyhow ?
Thanks for that :-)
I know touching the connectors on a UPS battery will make you regret it, from experience.
I've also watched a co-worker get tossed across a room by a 230V 20A line because he stuck a screwdriver in the live socket (I guess he deserved it).
- Michael T. Babcock (Yes, I blog)
I think this would be a great deign. Maybe houses would one day have one large capacitor in their basements just like a heating oil tank. The service from the power company can be directly connected to the one large cap, and the house service panel can be stepped down and connected to the service panel and supply the house with power, with a special outlet to provide the high output to supply cars or other larger power sources. This would also alleviate the power grid from brownouts as during peak power period in which power can be coming from the cap and slowly recharge during the day at acceptable intervals and it can replenish lost power during the day at night when there is less load on the grid. ~Truckie174
This kind of energy storage technology may make the energy-based weapons which are a staple of science fiction practical/off the shelf. Not that I don't like your mental image.
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