Building a Laptop Trickle Charger? 53
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?"
A likely story (Score:1, Offtopic)
Invert (Score:3, Informative)
Re:Invert (Score:2, Informative)
Re:Invert (Score:1)
Inverters are cheap and simple (Score:1)
Re:Invert (Score:1)
Model M's, the only keyboards you'll ever need... and the only ones I'll ever use.
Re:Invert (Score:1)
Will it work? (Score:4, Informative)
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.
Re:Will it work? (Score:2)
Re:Will it work? (Score:2, Informative)
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.
Li-Ions are fun... (Score:2)
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 electro
3rd possibility.. (Score:2)
Or I suppose just plug in the laptop to the inverter - how boring is that? ;)
HUH (Score:2, Informative)
I hit it on the first link of a yahoo search. So, for that, you get the big middle-finger-in-the-face award.
Re:HUH (Score:2, Insightful)
Calm down before you flip somebody off.
Re:HUH (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
Re:HUH (Score:2)
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.
Re:HUH (Score:2, Flamebait)
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
Re:HUH (Score:2)
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
Re:HUH (Score:2)
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
Re:HUH (Score:2)
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
Re:HUH (Score:1)
Re:HUH (Score:1)
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.
Re:HUH (Score:1)
Re:HUH (Score:5, Informative)
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.
Re:HUH (Score:4, Interesting)
I would like to post any pictures from your trip... www.yzedf.com
Re:HUH (Score:2)
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?
Re:HUH (Score:2)
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.
Re:HUH (Score:1)
Re: It isn't AC. (Score:1)
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 woul
Consider a few things... (Score:4, Interesting)
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!
Re:Consider a few things... (Score:2)
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.
Re:Consider a few things... (Score:2)
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
Re:Consider a few things... (Score:2)
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 wei
One additional question: (Score:3, Funny)
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.
..if that bike... (Score:1)
Can't say. (Score:2, Funny)
Few options... (Score:4, Informative)
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 [nationalse...ductor.com], Linear Technology [linear-tech.com] or Maxim [maxim-ic.com] 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.
Re:Few options... (Score:2)
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.
Re:Few options... (Score:2)
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 co
Re:Few options... (Score:2)
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
Not an answer to your question, but maybe helpful (Score:1)
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
Re:Not an answer to your question, but maybe helpf (Score:1)
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 tha
Ask Greg Frazier (Score:2, Informative)
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
Google to the rescue (Score:2)
Solar powered 12V trickle charger (about $40) [batteries.com] to run into the bike's battery, then get a auto/air adapter for the powerbook [macmall.com]($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, e
Check Lind (Score:2)
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
use the mains at the repair shop. (Score:1)
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.
MCE Tech (Score:2)
If your bike is being converted to 12v, see MCE Tech [mcetech.com]'s Auto power adapters [powerbook1.com], 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 p