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Building a Laptop Trickle Charger?

Posted by Cliff on from the recharging-on-the-go dept.

chimpo13 asks: "In 18 months, I'm planning on riding around the world on a 1966 Ducati 250 single. I have some problems, but there's one that can hopefully be answered on Slashdot. I think my Powerbook G3 will take the vibration of the bike, but I'm trying to find out how to trickle charge the laptop battery on my bike. It's a 6 volt bike that will be converted to a 12 volt. Has anyone built a trickle charger for a laptop?"

53 comments

  1. A likely story by L.+VeGas · · Score: 0, Offtopic

    Trickle charge to your laptop, huh? I want to do this too. Computer? No, I don't need a computer.

    --
    Best Windows Freeware
  2. Invert by Ledge · · Score: 2, Informative

    Why not just hook an inverter up if you are going to convert it to 12 volts?

    --
    If it ain't a Model M, it's a piece of crap.
    1. Re:Invert by cymen · · Score: 2, Informative

      In my experience inverters are very wasteful in terms of energy requirements and motorcycles are very fruagal in their providence of said energy. In other words, even modern bikes 700cc often have a hard time powering heating riding gear let alone inverters. This old bike probably won't have enough juice to power little more than the headlight.

    2. Re:Invert by cymen · · Score: 1

      Oh yeah, has the story poster considered a KLR-650? Not romantic like your current choice but it should get you there and back. /me goes off to motorcylce troll elsewhere

    3. Re:Invert by longbottle · · Score: 1

      Kinda offtopic, but I love your sig. :)

      Model M's, the only keyboards you'll ever need... and the only ones I'll ever use.

      --
      I don't suffer from insanity. I enjoy every minute of it!
    4. Re:Invert by MarcQuadra · · Score: 1

      Inverters are really inefficient. They suck a TON of juice.

      --
      "Sometimes, I think Trent just needs a cup of hot chocolate and a blankie." -Tori Amos on Nine Inch Nails
  3. Will it work? by TheSHAD0W · · Score: 3, Informative

    I don't know if your notebook can be easily connected to trickle charge. Most laptops' DC in are designed for a full-current connection, and the charging circuitry won't function properly with a less-than-optimal supply.

    There are two possibilities I can see; one is, to remove your battery (or get a spare) and trickle-charge it outside of the laptop; or to trickle-charge an external battery and use that as a voltage input. I recommend the latter; I don't know what the Powerbook's battery terminals are like, but I suspect it'd be inconvenient to hook up to.

    1. Re:Will it work? by chimpo13 · · Score: 1

      Thanks, this is EXACTLY what I'm looking for. It hadn't even occured to me that I might not be able to even trickle charge the laptop.

      --
      riding round the world on an old motorcycle
    2. Re:Will it work? by GigsVT · · Score: 2, Informative

      I don't know what the Powerbook's battery terminals are like, but I suspect it'd be inconvenient to hook up to.

      If it's Lithium Ion, better be careful charging it. They can and will explode if not used with a proper charger setup. Other types of battery are much more tolerant of dumb chargers.

      --
      I've had enough abrasive sigs. Kittens are cute and fuzzy.
  4. HUH by mugnyte · · Score: 1, Informative

    this guy built one and it seems rather trivial.

    I hit it on the first link of a yahoo search. So, for that, you get the big middle-finger-in-the-face award.

    1. Re:HUH by jargonCCNA · · Score: 2, Insightful

      Actually, that's not quite what the article is looking for. Can that trickle charger interface with a Powerbook? Doesn't look like it.

      Calm down before you flip somebody off.

      --
      Matthew G P Coe
      http://mgpcoe.blogspot.com/
    2. Re:HUH by chimpo13 · · Score: 4, Informative

      That's dc to dc. The bike is ac. The alternator will probably put out about 100W. It also needs to run my headlight, my taillight, and my brakelight.

      I don't know much about electronics, but I'm learning now.

      Here's stuff I've heard from an electrical engineer who has old Ducatis:

      First, if you choose to implement a charger running off the bike, the charger will have a cord that plugs into the computer presumably through the carrying case. You'll have to plan in advance how long the cord needs to be, and you'll have to route it so it doesn't conflict with any moving parts.

      The AC configuration presents some special challenges. Batteries are DC creatures. A rectifier (a diode) handles the job of converting AC to DC nicely and cheaply.

      We like to design something called a full-wave rectifier, because that uses both positive and negative AC (alternating current) cycles. The trouble is, you need a reference contact to the center of the AC transformer, which in your case is the bike.

      The AC bike doesn't provide that. It can't be done because one side of the "transformer" is tied to the bike frame as a ground reference.

      That means all you can implement is a half-wave rectifier. So exactly half the time you're getting some voltage, and the other half of the time you're getting no voltage whatsoever. You have to average the two together, so some voltage averaged with no voltage equals significantly less than some voltage.

      Now we have DC voltage, but its pulsating DC. This isn't any good either. When the instantaneous DC voltage is above the voltage of the battery, the battery will charge. But when the DC pulse goes to zero volts during the unusable half-wave, of during the usable cycle when the DC voltage hasn't risen to the at least the same voltage as the battery, the battery will actually loose charge as it tries to send power to your charger!

      So now another diode is needed to limit current flow to the battery and prevent current flow away from the battery.

      Confused, I hope not. But there's more. We've got pulsating DC that's going from 0v to 10v DC. The 3.3 volt battery of the laptop might be destroyed by too high of a charging voltage. Now we need a special diode called a zener diode that regulates (not rectify) the voltage so we don't apply too much voltage to the battery.

      So now, by using a few diodes, we're shooting a tiny charge into your battery when the voltage is above your battery level, but not above the upper limit of battery charge. So for a few milliseconds of every cycle, as the pulse of DC rises and then again as it falls we get a tiny amount of charge into the battery. We can make up some ground by adding a capacitor to store some energy which we take when the DC pulse is too high a voltage for the battery level. But still, we can never make up for the fact that we can't use exactly half of the AC cycle.

      What I'm trying to get at here is that the constant 6 volts DC from a DC motorcycle can easily be regulated to the charging voltage of the batteries in order to supply a continuous recharge. The AC system would take some doing to make an effective charger for your laptop batteries.

      You need to see what your AC adapter or your car adapter say their output voltage is to the laptop. They should be the same. Maybe it will say something like 3.5 VDC, and it might even give a current specification, like 100 mA or 500 mA.

      You'll need a cord with the correct plug to mate with the laptop. I don't trust radio shack quality, but I'm not sure where else you can get the cord. If the car adapters are cheap enough, you can butcher one of those. They should have a higher quality cord.

      --
      riding round the world on an old motorcycle
    3. Re:HUH by mugnyte · · Score: 1


      no mention of running the laptop while on the bike. in this case, a battery is what he's dealing with.

      the point is /. is not a search engine - that was just the first link from a cheapass search. this post looks suspiciously like there's no research behind it. there are quite a number of circuit design sites out there. yawn.

    4. Re:HUH by stubear · · Score: 1

      "...but I'm trying to find out how to trickle charge the laptop battery on my bike."

      You mean this didn't clue you into the fact that he's looking to recharge the laptop while on his bike? Funny, it seems to be explicitely saying just that.

    5. Re:HUH by BigBir3d · · Score: 3, Interesting

      Considering Ducati's of that era have absolutely horrid electrical systems, I would use a seperate battery for the charger. At some point, you will most likely use it as a spare for the bike anyhow. I can not highly recommend enough going for a gel battery, no worries about loss of fluids during accidental tip overs, no boiling off in hot weather etc.

      I would like to post any pictures from your trip... www.yzedf.com

    6. Re:HUH by mugnyte · · Score: 1, Flamebait

      IS THE LAPTOP SUPPOSED TO BE ON OR JUST STORED?

      if he is keeping the laptop running and recharging ala as if we were plugged in, then this is a more complex problem. also, it seems kinda silly to me.

      if he is simply storing the laptop for the jaunt, then just pop out the batteries and put them in a simple trickle charger. 12vAC rectified to 12vDC transformed to 6vDC limited to %1 of max discharge mA.

      sheesh man, read MY post. Its not about a bike. Its about doing a SEARCH first

    7. Re:HUH by chimpo13 · · Score: 1

      I have searched and I've been asking all sorts of people. I think part of the problem is, I'm not electrically minded.

      Common sense isn't something that's common. When you've done something a long time, you think everyone should know how to do it. For you, knowing what I should be trying is easy. How are you at rebuilding an engine? I'm not going to sit over you making fun of you when you ask questions trying to rebuilt one. Although finding out how to rebuild an engine is a lot easier to find out how to trickle charge a laptop.

      The laptop will be stored and used when I'm not riding. I don't think I'd be a very good typist while riding a bike. Maybe I'll try coding when I'm riding to work though to see how that works out.

      A Ducati is ran off a magneto. No battery and it's 6 volt. The lights on an old Ducati don't work that well. So I'm going to have to switch it to 12 volt, put in an alternator, and run a halogen light. I think the largest alternator that will fit is 100W, and that needs to supply my lights and the battery that I'll have to add.

      --
      riding round the world on an old motorcycle
    8. Re:HUH by mugnyte · · Score: 1


      Good info. My suggestion: Sell the powerbook and Ducati and buy a bigger bike with a battery and a Palm along with you to read/write email.

      Seriously, if you are nowhere near a good source of electricity for this long, wouldn't a piece of paper and a pencil still be the easiest way to keep notes?

      If you are near a telephone to read/write email, there should be some sort of power source nearby. Especially if you are looking for petrol every X km. No vibrational damage either (save for the wrists and arse).

      I don't think its even worth the geek factor to adjust too much for a powerbook. If you are making changes to the bike for other reasons, good on'ya. Even hauling a laptop seems excessive for a motorbike trip. Internet cafes exist in a lot of places, as well.

      I still have my journals from bike trips up and down the US west coast. Doodles and sketches add a lot to it. A laptop just didn't fit with the air of a road trip, to me.

      Good luck

      mug

    9. Re:HUH by chimpo13 · · Score: 1

      I like small bikes. I'm not in a hurry and I want to see things. There's a lot more bikes that are better suited -- stuff like BMW 650 and KLR650s. But I want a small light unusual bike. I can work on it, so I'm not worried if it breaks down.

      I figure with a laptop, I can have a place to store photos and do a site of my wacky shenanigans. Which I'm sure will say, "Day 83. Zanzibar. Man, my ass hurts." But I'll also be bringing paper and a pencil because I don't know if my laptop can survive the abuse. Although when I see wild elephants, I'd draw a horrible picture of 'em.

      I'm not sure how often I'll be able to reach a phone to update. And I'm not going to be staying in hotels a lot. Plenty of camping by the side of the road.

      My favorite post so far is, "Wear an hat with solar panels. That would look great on you. Also, don't forget to add a night lamp to your bike (just above your head) and then you'll look like a perfect weirdo". But it's been modded down to invisibility.

      I'm probably going to use solar panels for the digital camera batteries.

      --
      riding round the world on an old motorcycle
    10. Re:HUH by Hadlock · · Score: 1

      in an airline magazine, and probably elsewhere, you can find a solar 12v car battery trickle charger, it is roughly 5x18" and maybe 3mm thick. they run about $100, and while you wouldn't be trickle charging the battery off of the engine any more, it would likely be more reliable overall. maybe that will help some. what website will you be posting your updates to?

      --
      moox. for a new generation.
    11. Re:HUH by chimpo13 · · Score: 1

      It'll be posted to rtw.nokilli.com but of course, I need to fix my cornputer at home. Part of todays plans...

      If it's a car battery trickle charger, would it work on a laptop? I've been told that laptop batteries are picky about how they're charged.

      --
      riding round the world on an old motorcycle
    12. Re:HUH by Webmoth · · Score: 1

      "The bike is ac."

      Well, um, pardon my ignorance, but... couldn't you just use a transformer, then, and, like, y'know--step it up from, oh, say 12VAC to 120VAC?

      Then you could, maybe, just plug in the laptop's regular ordinary PS into the xfmr. That would be suhweet.

      Am I missing something here? Like: needs of the powerbook exceeding the capabilities of the bike's altenator?

      --
      Give me my freedom, and I'll take care of my own security, thank you.
    13. Re:HUH by Hadlock · · Score: 1

      well you had mentioned that one of the major problems was getting a semi-steady power source, and that your motorcycle engine, over a wide range of revs, would produce different amounts of current, and whatnot. this should at least help you in the slightly more predictable current department (assuming a fairly sunny day each day). it might be worth it to invest in a second small 12v battery and charge the G3book off the battery that is being charged by the solar 12v trickle charger via a 12v adaptor for your powerbook. i am using a similar setup for my PSOne, sans the trickle charger, 12v motorcylce sized battery from radio shack, cigarette lighter adaptor, and a 12v adaptor for my PSOne, and then the PSOne attached to that. your setup would be similar, but with a solar trickle charger charging the battery and a powerbook and cigarette lighter adaptor for your powerbook (i know they make one for my tibook, and pretty sure they have one for a g3 powerbook). this would keep the ducati from being bogged down by the charging off the alternator, if nothing else. if you wanted to, you might be able to run both batteries in paralell/series (i forget which one simply gives you added capacity w/o doubling voltage) for better reliabilty of the system overall at the cost of increasing the complexity of your system signifigantly. or you could just add the solar trickle charger to your existing battery with a logic switch attached to the charging line to your battery with a switch that would give juice to the laptop via a cigarette lighter adaptor only when it was fairly bright out with a light meter, or an "angle meter" when the bike is going downhill, so that the engine is only charging when going downhill and you're not overstressing your engine and alternator. ok i'm done rambling. i'll check out that site hopefully in 18 months.

      --
      moox. for a new generation.
    14. Re:HUH by chimpo13 · · Score: 1

      How would I step up the voltage?

      If I can get a 100W alternator (and that's a mighty big "if" I'm guessing 80W), the halogen headlight is probably 50W. I'm not sure of the tail light/brake light.

      Like I've said, I'm not good with electricity. Now I'm not even sure if a laptop trickle charge will cook the batteries.

      But anyway, now I have new info to give to James, the Ducati-minded EE, and hopefully James can figure something out.

      --
      riding round the world on an old motorcycle
    15. Re:HUH by Nakarti · · Score: 1

      Are ye all retarded? If the bike supplies AC current, use a transformer to raise the voltage, and sent that into the laptop's existing power adapter!

  5. Consider a few things... by heldlikesound · · Score: 3, Interesting

    1. In 18 months time handhelds will be even more capable than they are now, not to mention more energy effecient and easier to get online. Plus becuase they use different power schemes, you have more options for recharging the units via the sun, or your bike, etc... Plus, it makes sense to bring a cell phone. A blown tire, or God forbid, a wipe out, could leave you in a tight spot if you have no way to contact somebody. Why not combine your computer and your cell phone in a handheld? NO there are not really great examples of these devices right now, but there WILL be in 18 months!

    2. I assume your trip is similar to backpacking in which we think about every ounce as basically "costing" us carrying energy and the ability to bring something. In this case, taking a computer like a Powerbook G3 (like the Walstreet, Pismo, or Lombard) is pretty expensive weight-wise, if HAVE to take a computer, bring a 12" iBook.

    3. If you choose to go the PDA route, think about using the weight you save to bring a really nice SLR digital camera, instead of a little canon Elph or something... Also, GPS would be nice, but by that time i imagine it will be in the PDA that i describe above.

    Mind you, i am putting a bit of faith in the steady progression of handheld devices, but i don't think that is unreasonable given the inevetiable convergence of cell phones and PDA's...

    Now a question for you....

    How did you get off work for that long!!!?!?!?!?!??!

    Good luck!

    --


    Cloud City Digital: DVD Production at its cheapest/finest
    1. Re:Consider a few things... by chimpo13 · · Score: 1

      I'll see what they have in 18 months, and hopefully something better and cheaper will come out. Right now it's a powerbook, because that's what I have. Money will be an issue though. I'm selling off all my stuff on eBay before the trip.

      I'll use a solar recharger for my digital camera batteries.

      The laptop is just for keeping a blog. I'm not in any rush on the trip. It'll probably take me 3 years. Since I'm on a bike, I can't use it while I'm riding. It's a small bike that doesn't put out much power. Things would be much easier if I was on a BMW or a Goldwing. But I don't want a large bike.

      I can change tires, and work on my bike. I don't know how much a satellite phone will cost, but I've been looking into that. I don't think calling AAA and saying "Uh, I'm in the middle of Madagascar with a blown tire. How long until a tow truck shows up?" will work. Hopefully when I fall off, I won't break any bones.

      I don't mean to be a smart ass, oh wait, I mean to be a smart ass, but I don't mean to do it in a mean way. I'm keeping a sense of humor about this trip.

      I'm telling my work, "Uh, I quit. I'll reapply in 3 years maybe".

      One of the fun parts is I'm epileptic. I still haven't figured that one out yet.

      --
      riding round the world on an old motorcycle
    2. Re:Consider a few things... by billn · · Score: 1

      I did a road trip on my TL1000 a couple years ago, and ran into a similiar problem, wanting to power my Nomad Jukebox. What I wound up doing was installing a cigarette lighter plug in the (small) compartment under the pillion. Using a six foot extender, I ran the wiring through my chassis from the rear end, to pop up under the front lip of my seat.

      I lopped the end off and attached a quick disconnect connector set at that point, even going so far as to cut off the plastic retention clip so it wouldn't snag in case I ditched and got thrown. The rest of the assembly tucked into the back pouch of my hip pouch, with my 6 gig jukebox in the large pack. Worked out well, especially at gas stops, since connecting and disconnecting from power was no hassle. With rechargable cells in the nomad, I could have non-stop tunes. With the noise-cancelling processor clipped to my armor, I could still cut out the tunes in case I needed to listen to something.

      Caveat emptor, don't run your volume too high if you do this. You should still be able to hear what's going on around you. The NC-10's cut out almost all the wind noise, and overlaying music on that pretty much eliminated it, but you still need to be aware of your surroundings. I ran mine at a volume that I could still talk to people and understand them with my helmet on and my NC processor cut out. I've also got a Koss mini-headphone amp that I kept tucked into my pocket that had a volume control that was much easier to access than the one on my Nomad (at the time). Radio Shack carries these as well (also good for laptops on planes!)

      This whole kit, combined with Sony NC-10 earphones under the helmet, did a lot to preserve my sanity for the couple thousand miles I rode. Storing my cell phone and car charge in the remaining space under my pillion also made sure I never lost it, and it was always charged. =)

      When planning your trip, don't just plan for gas stops. Allot at least 10 to 15 minutes to a pit stop, take the time to stretch your legs and back. Don't plan on riding more than eight hours a day. Fatigue is far more deadly on a bike than it is in a car!

      Camelbacks are a good idea, with a half and half mix of water and gatorade (I loaded mine with Sobe once.) Try and steer clear of soda and similiar, since the sodium is a dehydrator. Grab a few bananas now and then when you get the chance, it'll cut down on muscle soreness. I highly recommend a short haircut, too. After a while, that helmet jerking on your hair all the time actually starts to induce some follical pain. Make sure your boots are broken in before hand, too.

      Most importantly, take a damn camera. Depending on your route, you'll get to see things you'll want to remember. I kept a little disposable in my jacket pocket for those fast quick shots that hauling my SLR out were just too much hassle for.

      Lastly, enjoy the ride! =)

      --
      - billn
    3. Re:Consider a few things... by Mignon · · Score: 1
      The laptop is just for keeping a blog.

      My recommendation would be to see if you can use a handheld with external keyboard - you'll save weight and space and without a hard drive and such, it should hold up better to driving. Also the battery charging issue should be moot, provided you can get batteries easily. I get several weeks, maybe a couple of months, from a pair of AAA's in my Palm III. Even for a three-year trip, I suppose you could carry enough batteries with you and still be talking about less weight and space than a laptop and this mystery trickle charger.

      The part I can't tell you about is whether you can update your blog from a handheld. I don't know what the blog interface is like - e.g. do you ftp an HTML file, or do you use a web-based form? There might be some Palm software for doing just this kind of thing. I never cease to be amazed at the kinds of software that people have written for these devices.

      I have used my Palm III, a Stowaway folding keyboard, and an external modem on several trips for keeping a diary and doing email. I do it in batch mode which means, for those of us spoiled by always-on connections, connecting to send accumulated outgoing mail and retrieve waiting mail, then disconnecting and replying while off-line.

      One of the fun parts is I'm epileptic. I still haven't figured that one out yet.

      Good luck!

  6. One additional question: by cybermace5 · · Score: 2, Funny

    Circumnavigation is best done with a ship. Do you plan on rafting the Ducati over the oceans, or driving on the sea floor?

    Oh...and your G3 will be dead in 18 months. And if the vibration doesn't kill it, nothing will. And...just get an inverter and run 12volts to the saddlebag. You don't have to leave it plugged in all the time.

    --
    ...
  7. ..if that bike... by zogger · · Score: 1

    ..if that bike runs it's electrical on a magneto I can guarantee you don't want to hook it directly up. Spike city. Your best bet is to get a 12 VDC car adapter, charge the batts separate,out of the laptop somehow, or let them recharge from your bike batt when it's stopped. Don't try to run the laptop with the motor running in other words. You can also get a flexible solar PV panel you can strap on top of your gear, so it will get some juice while you are driving and stopped. Unisolar makes them, different sizes, you can google for them, easy to find. I have two of them, work great! We have those for our backpacks here, to recharge small batts, so I guess a laptop batt isn't much different, just need to make sure you watch them, the voltage is unregulated, brighter sun, higher voltage. To get around that you can use a "charge controller" thing. Very large batts like car batteries don't need it, but I am just not sure about smaller drycells, although I've done it, I haven't done it a *lot* like for the time lengths you are suggesting, I just know it's possible. Might be a good idea to install dual batteries for the bike itself, so one can be recharging the laptop at night while camping say, leaving one for running the bike in the morning, switch them around or re-attach in parallel before you take off for that day's ride in the morning. I don't know if that bike is kick start only or electric or both, but you need some juice to start it either way as far as I know.

    Besides that, NEAT TRIP MAN! Sounds like lotsa fun!

  8. Can't say. by schoolsucks · · Score: 2, Funny

    You say that you are going on a world tour on your bike. This is Slashdot, anything mentioned here must have a website associated with it. So where is your website and photos of your bike?

  9. Few options... by stienman · · Score: 3, Informative

    There are probably 6v to 120vAC power inverters which should do the job just fine, and will be the easiest and fastest way to go. Just plug your power adaptor into it and then into the laptop and you're done.

    I suspect they are rather expensive though.

    The other alternative is to make an adaptor that goes directly from the battery to the powerbook. Since you didn't give any specs on the power requirements of the laptop you're talking about (and yes, the different powerbooks and ibooks have different power adaptors) then I can only give some general suggestions.

    Unless you are an EE (or aspiring to be one) then don't get involved with switching regulator design and go with the option above. If you must, then go to National Semiconductor, Linear Technology or Maxim and look at their parametric guides to the power regulators. What you need is a switching boost regulator. If you are exceptionally lucky, you'll find just the part you need with the exact application note for input voltage, output voltage, and supply current. I doubt it though. Then you'll need to buy the parts and assemble it. Getting all those tiny surface mount parts on a bread board is only half the fun, though you can still get many parts in through hole.

    Of course, neither of the above two methods result in a 'trickle' charge. It'll still suck power from your bike while charging, which leaves the last option:

    Charging the battery directly. Just don't. If you don't know enough that you must ask slashdot (of all the places...? Why not sci.electronics.design or something? Egad...) Sorry, uh... Yeah, like I said, if you think the best place to find out is slashdot, then you don't know nearly enough to properly charge your battery directly without damaging it. Plus you still have the problems of building a step up switching regulator on top of the charger, since the battery will need a higher voltage than your 6v motorcycle cell.

    However, I will give you a general overview: Battery charging is essentially a current (not voltage) operation. You force a certian amount of current in for a period of time, and the battery releases some as heat and stores the rest. Lithium Ion batteries are very finicky when it comes to charging. You will reduce your batteries capacity by 10% or more each time you charge it incorrectly. If a battery costs you $100, then it's worth doing it right, and in your case I think the only 'right' way is to use an inverter and the laptop's internal charger. Furthermore, Lithium Ion batteries do not like being trickle charged. When done properly it doesn't hurt them, but it doesn't give them a good full charge, either. Lastly, LiIon batteries are well known for their inability to take many charges. Early cells couldn't handle more than 500 charge cycles without losing most of their useful capacity. State of the art cells now don't go over 800. Trickle charging excacerbates this issue.

    If you can get NiMH batteries for your laptop then I'd say you have a good chance, since you can go to your local hobby shop can get a charger from them, but they still take 12v so we're back to square one. If your LiIon is only 10.8v then you can get LiIon chargers from the model airplace community, but those are also usually 12v or 120vAC.

    So, in closing, I'm still strongly advocating usage of a regular inverter with the laptop's own power brick.

    Good luck on your trip!

    -Adam

    Yet another reason I loathe Apple (not the products, the company): they don't have power specifications on their website about the laptops. The have the input specs to the power brick, but not its output or the laptops input and current requirements, nevermind the battery V and I. I know they have to dumb things down for the average user, but at least put some real technical specs on the technical specs page instead of the fluff they currently have there.

    1. Re:Few options... by chimpo13 · · Score: 1

      I have a 500MHz PowerPC G3. I'll have to look into what sort of batteries I can use but I don't know if there's much of a choice.

      I don't know much about electronics, you sure have that right.

      I would just like a way of charging my laptop from a small bike. Maybe I should put you in touch with the EE who's been helping me. He knows a lot about old Ducatis and you seem to me like you know laptop batteries.

      --
      riding round the world on an old motorcycle
    2. Re:Few options... by chimpo13 · · Score: 1

      Okay, more words from my Duc EE guy:

      I haven't read that guys answers all the way through, but from the little I've read so far he seems well informed.

      The power brick he speaks of is not an option for you though.

      Why?

      Reason number one is they just don' make them. Since no one has made 6V automotive systems for so many years that there is no demand.

      Secondly, remember that website you sent me for the 12Vcd car adapter plug? The commercial 12v power converters for you model of Apple are made to run the computer from the automotive source. At 12 volts they require 45 watts of power from that automotive source. You need 45 watts of power regardless of all other factors, but if you drop the voltage in half that means you'll need twice the current to keep the same number of watts. The 12v adapter has to consume 4 amps to keep up with a 45 watt demand. At 6 volts, you'd be drawing 8 amps out of the bike!

      All you have is a 40 watt alternator at best, and I can't guess the gauge of the wire needed to safely carry 8 amps. I'll read the email more thoroughly next week.

      Jim

      --
      riding round the world on an old motorcycle
    3. Re:Few options... by stienman · · Score: 1

      Ok, you can find a 5V to 12V DC to DC converter at MPJA but it only supports 1A of current.

      You might give it a try, though, since the laptop in charging mode should consume less than one amp. I doubt you'll have any issues with putting 6v in instead of 5v, but buy a few (they're cheap) and find out.

      Get a car adaptor (cigarette lighter type) that powers your laptop in a car and hook it up to the DC to DC converter. In a pinch, if you need more current, your friend can use two or more converters with .1 ohm resisters to supply more current (one resister on the output of each supply, then the output from the resisters can go together)

      If your friend can build one, then he should not have too much problem finding a boost switching regulator that'll take 4-8 volts and output 12V at an amp or more from one of the suppliers listed above. In some cases the WebBench from national semiconductor will design it for you, and they will even sell you all the parts and a suitable PCB for under $20 for some converters.

      Switching supplies are difficult to debug and are considered somewhat of a black art among EE types, which is why I was warning you away from it before.

      Good luck! -Adam

  10. Not an answer to your question, but maybe helpful by darthwader · · Score: 1

    When I do my motorcycle touring, I usually use the credit-card-camping technique (restraunts and motels). Motels provide a simple place to plug in the laptop overnight, and even in a restraunt you can get an hour or so of charging time while you eat.

    I get the impression that you will be roughing it more than I do. But if you aren't using the laptop much, you won't need much charging time. So you may be able to get away with finding somewhere to plug it in every few days, and not worry about overloading your bike's electrical.

    Which brings me to my second point. If you are going to install any extra electrical on your bike, I suggest you talk to your mechanic about replacing your bike's rectifier with a stronger one. I don't know how good or bad your bike's electrical system is, but I do know that on my bike, adding any electrical load (including extra-bright lights) will cause the rectifier to burn out after a few months use.

    --
    I hate it when I make a joke and I get modded "+5 insightful". Mod the stupid comments "funny", not "insightful", pleas
  11. Ask Greg Frazier by gmhowell · · Score: 2, Informative

    Ask Greg Frazier. He writes many stories for Rider magazine on circumnavigations via motorcycle. I believe he was wired with laptop for his latest jaunt.

    As far as charging, I'd look into some of the solar rechargers. Don't think a vintage Ducati's charging system could keep up.

    I found this address with a quick google search: gregfrazier@yahoo.com

    --
    Jesus was all right but his disciples were thick and ordinary. -John Lennon
  12. Re:Not an answer to your question, but maybe helpf by darthwader · · Score: 1

    ... It's probably bad karma to reply to my own post, but what the heck!

    I used the word "rectifier" without much of an explaination of what it is. This is mostly because I'm not an EE, and I don't know in great details what it does. In general terms, however, it's part of the system that takes the power from your alternator, and smoothes, polishes, and munges it into a form that's suitable for charging your bike's battery and powering your bike's electrical system. It normally generates heat (perhaps that's how it gets rid of excess energy?), which is why it has a heatsink attached to it. If you increase the bike's power usage, youu increase the amount of power going through it, which increases the heat. Which, as I said before, causes it to burn out and stop working after a few months of over-use.

    When it stops working, you don't get charging power to your battery. Which means that after an hour or so, your battery is dead, and so is the bike.

    Is there someone out there with some specific info about what you need to do if you want to safely increase the current load on your bike? Like "replace your AB-240 model thingy with a newer CD-999 model thingy ($22.96 at Radio Shack)"?

    If not, maybe you can find a discussion list dedicated to your bike model, and there should be someone there who can tell you how to safely add electrical load to your bike without long-term damage.

    --
    I hate it when I make a joke and I get modded "+5 insightful". Mod the stupid comments "funny", not "insightful", pleas
  13. Google to the rescue by dr00g911 · · Score: 1

    I know it isn't specifically what you asked for, but you can buy a:

    Solar powered 12V trickle charger (about $40) to run into the bike's battery, then get a auto/air adapter for the powerbook($80), and a lighter/accessory outlet (about $5, with cable at Radio Shack or your local auto parts store) if you need one. This way, the alternator is feeing the charging usually, and the solar panel is 'topping off' the bike's battery, whether or not the bike is running -- handy to have for a trip around the world, even without the laptop, I'd imagine.

    Have you considered hooking a solar panel up to the laptop for charging and cutting the bike out of the equation completely? Not as reliable, and doesn't solve the 'I ran out of juice at night' problem, but worth a thought as you're undoubtedly going to be putting massive stress on the bike's battery and alternator. Googling for "laptop solar cell" will bring dependable results.

    Best of luck, sounds fun.

  14. Check Lind by Telecommando · · Score: 1

    Lind Electronics sells adapters for a variety of laptops. Check the "Auto Air Adapters" section.

    I've been installing Lind power supplies for the last 3 years to power mobile-mounted, Panasonic Toughbooks. Out of hundreds installed I've only had one go bad and it was jump-started by an idiot. I've had a higher failure rate on the Toughbooks. As far as the laptops are concerned, they think they're hooked to their normal AC adapter.

    The adapters we've been buying are completely potted with rubber inside and can be easily weather-proofed by putting a bead of silicone caulk around each connector.

    Disclaimer: It worked for me.

    --
    Beta sux! Join the Slashcott! http://hardware.slashdot.org/comments.pl?sid=4760465&cid=46173047
  15. Inverters are cheap and simple by michaelredux · · Score: 1

    I agree, why not use an inverter? They can be small, cheap (less than $50), and simple. I don't know how much your time is worth, buy unless I could solve this problem is less than an hour, I would probably go down to the warehouse store and buy one off the shelf. regards, michael.

  16. use the mains at the repair shop. by seregmcw · · Score: 1

    if you're riding a '66 ducati 250 you'll be their enough that you won't even need a battery.
    leave it at home.
    unless you plan on riding and geeking out at the same time.
    or did you want to sit out in the fields of flowers and compose love sonnets and haiku to your jelly tanked moto bolognese.

    --
    "Oh, I'm a janitor. I used to be a computer geek, but I got wacked in the head". --Dave um... "Smith"
  17. MCE Tech by Parsec · · Score: 1

    If your bike is being converted to 12v, see MCE Tech's Auto power adapters, which run about $30.

    I'd have to recommend doing a 12v conversion just for your sanity of finding parts on the road. You probably already know that it's not a question of if but when it will break, so try to make it easy on yourself to repair. Maybe even get a list of repair shops along your route before you set out.

    The full power adapter requiment of 45 watts is designed to be enough to run the PowerBook and a few Firewire/USB powered accessories, while also charging the battery. If you have the machine sleeping or even powered off while doing highway speeds, you may have enough juice from your alternator to charge it and keep your cycle's battery charged, while running the headlight.

    Happy trails!!

  18. Solar Power should Do thie job! by Anonymous Coward · · Score: 0

    Why not invest in a small powerful solar panel to charge your laptop and your bike! You may find the following site useful for this kind of technology www.FutureEnergies.com

  19. Google gives this answer: by Anonymous Coward · · Score: 0

    Use pencil and paper you moron! And film cameras.

  20. Li-Ions are fun... by Andy+Dodd · · Score: 1

    "trickle charging" the laptop itself will not likely be possible - Almost all laptops expect full current for charging. (Even when turned off, my dad's Dell Inspiron 8000 would overload and shut down our old inverter, which was too cheap and too small.)

    Trickling the batteries - Be VERY careful. Li-Ions cannot be constantly trickle charged. You SHOULD be safe giving the battery a low-current charge if you use a regulator set to 4.1 or 4.2v/cell (Depends on the exact battery chemistry, the type of electrode changes the nominal voltage slightly.) with a current-limiting resistor. But don't leave the battery in the charger, this will be bad.

    The way Li-Ions are supposed to be charged is a current-limited charge, but with the charge voltage never exceeding 4.1 or 4.2 volts per cell. At this threshold, the charger must go into constant voltage mode. Once the current goes below a certain threshold, the charger should start a timer and then shut down at the end of 30-60 minutes. Trickle-charging it beyond that 30-60 minutes is BAD. NiMHs and NiCds can be trickle charged at low currents (C/16 or less, the lower the better for the battery's health), and lead-acids (gel cells are a variant of lead-acid) like having a "float" charge of a constant voltage (Around 13-14 volts for a 12v lead-acid battery I think) applied constantly or regularly. (Car alternators typically provide this charge in automotives.)

    Note that even "deep cycle" lead-acids or gel cells should not be cycled deeply on a regular basis. lead-acids like to be topped off, as do those rechargable alkalines.

    Problem is that the pinouts and connectors for almost all laptop batteries are nonstandard, and some expect various control lines to be connected while charging. These connections are never documented.

    --
    retrorocket.o not found, launch anyway?
  21. 3rd possibility.. by Havokmon · · Score: 1
    He could always hook up a 12 volt inverter to the new battery, then hook up a 12v trickle charger to the inverter

    Or I suppose just plug in the laptop to the inverter - how boring is that? ;)

    --
    "I can't give you a brain, so I'll give you a diploma" - The Great Oz (blatently stolen sig)
  22. Re: It isn't AC. by citmanual · · Score: 1

    If that were the case, your bike battery wouldn't recharge. Your generator produces AC, the it is regulated and rectified down to ~12v DC.

    You have a 12v DC system that will have a tendency to fluctuate within a couple volts of 12. So, high RPMs will give you ~13-14v (depending on the regulator) and low will hopefully not drop below 10.

    Considering you have a 1cyl bike, that means relatively low rpms (unlike my 4 cyl sport bike, which redlines at 14k), so hopefully the cycles won't be as bad as that.

    I would add a second battery as the another poster mentioned to guarantee ~12v, not too mention it is damn handy. My bike died after having the lights on for a 45min traffic jam in Barcelona; 2500km from home. Thankfully, I had a friend and a busy tourist alley (Las Ramblas!) to push start. grin.

    Hook the laptop to the second battery.

    Also, having traveled extensively on a bike, I would highly recommend getting one of those super small laptops. The 800x400 display isn't nice to work on full time, but the extra space is priceless.

    Good luck.

  23. Laptop trickle charger by Anonymous Coward · · Score: 0
    If it uses NiCad or NiMh batteries, get a second battery. Hook it up to +12 volts with a series resistor. Pick a resistor value that gives charge
    current of 1/20 of the pack's capacity when the pack
    is charged.


    So if it is a 1000 milliamp-hour pack, pick a series
    resistor to give a 50 milliamp charge rate.

  24. Why Build ? by Anonymous Coward · · Score: 0

    Automotive electronics live in a really bad environment. There are occasional high voltage spikes, and all other kinds of nasties.

    I have seen after market devices designed to allow you to use your laptop in a car (ie plug into cigarette lighter) - I've been meaning to buy one for my Toshiba. I'd buy one of these and simply wire up a lighter socket to your 12V battery. If you just want to trickle charge your laptop, leave it switched off.

    Otherwise you're looking at building a switchmode DC-DC converted with a high tolerance for bad electrical environments - a challenging task and probably not cost effective.

    I'd stay away from the Inverter scenario - apart from the bulk of the thing, it's going to be far more inefficient and only worth persuing if you have other mains powered devices (can't be that much space on a Ducati). :-)