Ive got a Thinkpad 600e with a bad battery. So I gutted the batt. There were 3 groups of 2 batteries. Each cell is 3.4-4.2v 1.5a. The 2 are in parralel, to bring the ampers to 3, and the 3 are wired in serial, throught the smart (stupid) chip, bringing the voltage to 10.8-12.6v. What im wondering is if i could replace each of those groups of 2 with 3 AA Ni-mh 2500mah batteries. Would it charge, or will i just have wasted $20? If your wondering how this is linux related, Sqirt's running SlackWare 9.1 . Thanks.

I like the way you think. Don't know enough about battery technology, do we? My vote is on http://www.batteryrefill.com/ . Gads, I hope I'm not breaking the rules on the forum by posting a source.
Hope this helps.

A nimh battery back with the same voltage should work.
BUT it will not charge with a li-ion charger. LIion cells are about 3V nimh 1.25. li-ion have a chip to prevent over or under chargeing that would ruin them. You would have to modify the laptop to work with these. Probably not worth it unless it is old and worth risking!!

the way its wired i could connect to bats together for about 3 volts. ther are three groups of 2 paralell cells in serial right now. And the smart chip is on the pack.

But ive got a new plan now. I read that when a 600 series batt dies its usually only one or two of the groups that really die (i tested mine and one group is a happy 3.25 volts right now, others are shot), so im going to buy a few more on ebay (there about a buck each) or a recycling play and see if i cant gut the goot parts and make a good one. And now ive actually got some incentive since i got apm working

You can use the NiMH batteries to power a notebook computer, but do not use the AC to DC converter that connects to the notebook for charging. Charging NiMH has the same problems with Li-ion, but less picky. I suggest C sized batteries instead of AA sized batteries, so the notebook computer can use for the whole entire day depending on the work load. You can buy Li-ion batteries at electronic stores like All Electronic, Jameco, and probably Digi-key.

You will need about 9 NiMH batteries connected in series to provide the necessary voltage, but it would be 11.25 volts. Hopefully that voltage should be within limits, but I do not know.

The site that noridlo45 gave is a good one if you want a better battery at a much lower price.