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NeXT
January 22nd, 2009, 05:28 PM
I had two battery packs for my DUObook 230. Both are NiMH and before they were put away two years ago they were fully cycled and then recharged.
I pulled the system and the batteries out today and to my dismay neither battery wants to hold a charge anymore. Either I get a battery with an X in it or I get a battery that is fully charged but dies the instant you pull the power cord and the DUO battery reconditioner is apparently not compatible with my DUO (how ironic). Since it's just too much to get replacement batteries off ebay, is there a more "persuasive" way to get the batteries to charge? I really want to take this notebook to school to do word processing on. I still consider it the Macbook Air of the 90's and I use it with my Messagepad 130.

Terry Yager
January 22nd, 2009, 05:37 PM
Have you disassembled the pack(s) to see what size cells are used? You can sometimes revive shorted cells by zapping them. More details if needed, YMMV.

--T

NeXT
January 22nd, 2009, 06:16 PM
The two I knew were good I have never opened as they are pretty much welded shut but I have another DUObook NiMH battery whose case just shattered on me one day (I have no idea how it got so brittle) and here is what it looks like. Sure isn't an intelligent battery.
http://i11.photobucket.com/albums/a166/ballsandy/PB232319.jpg
Speaking of which, the cells have no markings at all.
EDIT: How exactly would you zap the cells? I can think of one way but I would rather not risk having these M80-sized cells go boom.

patscc
January 22nd, 2009, 06:59 PM
Have you tried allectronics ? (http://www.alleclectronics.com)
They often have surplus NiMH cells of varying sizes. Not to point out the obvious, but you can figure out the cell rating by taking the pack ratings for voltage & current and dividing them by the number of cells.
patscc

Terry Yager
January 22nd, 2009, 07:04 PM
Are the cells exactly the same size as AA cells, or are they the ones that are slightly larger? From the count, (assuming 15v), I'd say 1.2v, and amperage can be deduced from the sticker on the pack/computer.

At this point, you have a couple of options:

1). Recell the pack, using AA cells with solder tabs, available from RattShlock, etc (requires some soldering skillz). May not remain charged as long as the originals).

2). Recell using cheap OTC AA cells, available from Harbor Freight (requires extreme care and better soldering skillz, but much less expensive). Also, more dangerous, as you'll be soldering directly to the battery, which can explode if heated too much.

3). Try to save your packs by zapping. Also very dangerous, for reasons which should be obvious.
First, test each cell (after charging) to see which ones are not taking a charge, and mark them somehow. If none are showing a charge, then you might have to zap all of 'em.
To zap them, I usually use a car battery, since there's always one around. Attach wires (rather heavy, at least 12guage) to the car battery's terminals, then momentarily touch the wires to the terminals of each of the cells individually. Only a second or less is required, any longer and you will bust sum'n. Recheck each cell. They should all be showing a small charge. If not, rezap the ones that aren't. If zapping a second time doesn't do it, they prob'ly can't be saved at all, so don't bother anymore. If they do look promising, charge the pack as per the instructions for the computer, and see how it goes.

If none of the above does the trick, there's perhaps something else wrong with the (smart) pack or the charging circuitry.

BTW, the zapping trick only works with NiCad cells that are shorted internally, not for other types of faults.

As always, YMMV, and this is to be done strictly at your own risk. If you hurt yourself of bust sum'n, all you get are the pieces. Not recommended for the faint of heart.

--T

NeXT
January 22nd, 2009, 09:23 PM
Yeah, theya re a bit fatter than AA cells and depending on how much replacement cells would cost I can either try zapping them or replacing them. I'll at least try a zap first and if that fails I'll have to get new cells. Also, how will I be opening the other packs? Like I said, they are welded shut.

Terry Yager
January 23rd, 2009, 02:33 PM
As long as they're bigger, you can replace them with AAs, but they won't have the same capacity. The standard ones are about 7-800 MA/hr, rather than the heavier ones which will run around 1-1.2 A/hr. How long they last depends on how much power the notebook draws, but still should provide adequate run-time. The ones with tabs are more costly, but easier to work with. The ones I get at Harbor Freight cost about 4/$5. regular price, or half that when they are on sale (frequently). I usually use a rotary tool to open the packs, then they can be epoxied back together.

--T

NeXT
January 23rd, 2009, 04:32 PM
That's not too bad. That would mean ~$15 to re-cell the pack which is not too bad.
I guess I can go at the seams with a dremel and a cutting disc.

EDIT: The laptop itself says it's rated for 24V DC, 1.04A however my guess that is for the charger

patscc
January 23rd, 2009, 05:41 PM
Yeah, that's the laptop supply. The cells are almost guarenteed 1.2 V cells. They look to be about 1/3 bigger than regular AA's ?
patscc

NeXT
January 23rd, 2009, 07:11 PM
Yeah, they are about a quarter to a third bigger than a regular AA.

Terry Yager
January 23rd, 2009, 10:05 PM
I dunno, they could be 2v each, which would make the pack 20v, closer to the charger's output. Have you tested any of them with a meter? Is there any info on the packs? (I just assumed 15v since it's very common for laptops).

--T

NeXT
January 23rd, 2009, 10:13 PM
Well that one pack I have open is reading 13 volts. :/

Terry Yager
January 23rd, 2009, 10:56 PM
Oh good, some of the cells are charging then. Test each one individually, and see if any are reading more than 1.2v.

--T