Extending the life of an Ion Battery [solved]

[alienjon]

I have an old ThinkPad 600 lappy and the Lithium Ion Battery that goes with it is, consequently, rather old as well. In fact I can't really use it unplugged for more than 5 minutes or so. I've been looking into getting another one kinda cheap off of ebay and I'm noticing that it is still, seemingly, in rather high demand. I've even seen several batteries that are up for sale that are going for about $10 but which openly state that they are 'broken.' I was just wondering why people would be selling such damaged batteries so openly and be expecting others to buy them. My only guess is that people can actually fix the problem, with the right tools and know-how. Is that just wishful thinking (cause if so, I would be interested) or do people just like to have funky collections of archaic, dead batteries lying around?

[Qdot]

Well.. if you really know what you are doing..

Batteries contain ENERGY. The can and will EXPLODE if mistreated. This will not be NICE, especially when you're not around

ok. now the real deal. batteries are usually Li-Ion cells connected in series. Usually what happens is that a single cell (rarely more than half of the cells in unit) develops a condition which will deteriorate the quality of the entire battery. If you can find a bad cell and replace it, you might well repair the battery.

How to find a bad cell? well, you need a regulated power supply with current limiter (laboratory PSUs are best!), you charge the cell under some 3.7V 0.5A(and watch the damn thing, they blow up sometimes, wear protective gear, a jet of flammable hot liquid is not exactly fun), and measure the voltage under load (like, under 1A discharge, 2A discharge etc).. if they can provide 2A, they are probably good. Yes, you'd be doing it without the usual electronics, so there will be no current limiters and no thermal protection.

Also, they have controllers. Controllers are devices which regulate the charging regime of the entire battery, for example protecting against overcharging (which would be spectacular 'vent with flame'). Unfortunately, in certain conditions, they don't work well, for example, most batteries will not allow to be charged beyond last full capacity.. problem? if charged in very cold or very hot enviroments, last full capacity is less than real full capacity under normal conditions. Try replacing the controller or resetting it.. again, know what you are doing.

[alienjon]

Thanks for the info While I actually think I have the tools to be able to try this, I think it would just be the wiser idea to just get a new one once I have the extra couple of bucks. Thanks!