Thinkpads Forum

This is why ThinkPad 850s are going to all die eventually, because no one ever removes the NiMH batteries (it's probably even worse since most sit around never being used):
http://i.imgur.com/Ql4RK1j.jpg

Fortunately this one made it through, but the connector shows the famous green NiMH "frosting". It may have to be treated with some vinegar later to prevent further corrosion.

This is also the cause of why many 701Cs and TransNotes die as well, which is why a few of the 701Cs here need repair / treatment (I've since removed all of the NiMH batteries):
http://i.imgur.com/TUzouSn.jpg

Remove the NiMH batteries from your ThinkPads! Always! It only costs a few bucks to make a replacement battery that's using something more stable like lithium ion.

Admin edit: Removed large inline images. Please read the Rules of the Road concerning image placement (<50KB and put a warning in the topic line).

Welcome to the forum! Nice collection of old Thinkpads there, btw. Not often to see a 850 and 4 701s in one picture.

For the 701s, it's particularly the main battery that can leak and cause havoc, but also the standby battery in the small compartment next to the main battery can leak. What's the purpose of the green battery in your 850? I can see a CMOS battery in the background. Is it the same as in the 701C; a standby battery?

One of my 701Cs has slight traces of a leak from the standby battery, but the battery was taken out before it got bad. I bought a replacement for it, but the connector doesn't fit, and the battery really isn't needed, so I think I might skip it. I think it's purpose is to give power for a couple of minutes so the main battery can be swapped while the laptop sleeps. Luckily none of my main batteries has had any leaks. I have never opened any of my 701Cs up to check the CMOS battery, though. They are dead, as I get errors on boot-up, but I have always assumed they are not the type that are prone to leaking. I might be wrong; do you have any experience with those leaking?

For those interested, here's some more info on those batteries: http://www.transnote.info/tt2.htm
It includes links to illustrated PDF files for battery-replacement.

The advice on removing the standby battery also goes for the 770 series, it seems. I took apart a 770 last weekend, and discovered that it had one of these green big standby batteries underneath the keyboard/palmrest. There was no visible corrosion on the battery itself, but there was some green/blue fragments on the connector plug. I don't know if that was something else, or if acid one way or the other could have gotten there. Anyway, I immediately opened up my collectible 770Z to check the status there, only to find that some smart previous owner had already removed the standby battery.

DO NOT use lithium batteries in place of the NiMH! The ThinkPad charges these batteries, if you're sticking a non-rechargeable battery in, especially a lithium cell, you're significantly raising the risk of an explosion or fire! Even if the lithium cells are rechargable the TP doesn't have the logic required to stably charge them.