Thinkpads Forum

I have my brothers I1400 2621-420, and it's having problems. It will run fine when plugged into AC power, but won't do anything at all on the battery. I checked the battery voltage with my DVOM, and it's at 11.5 volts. The battery has 10 volts printed on it, so 11.5 is great. Windows 2k reports it as only having 27% charge. The AC adapter is puting out 16.5 volts, it is rated at 16 volts. Does anyone have an idea of what could be wrong?

Obviously, you have a problem with the battery connection.

Look inside the battery compartment and make sure all of the connectors are clean and are not bent. Then do the same with the battery.

If you have a spare battery, it would be nice to see if it works better.

The battery has logic board in it, and that could be a problem. Unfortunately, you can't just replace the logic board; you have to buy a new battery pack.

Hope this helps.

Hi Bruce, i've already checked all the battery connections. I was wondering what switches the machine from AC to battery, and thought maybe that component is bad. Keep the replies comming, and thanks.

Don't know if this is the case here, but...

I have seen "bad" batteries which measure the right voltage when there is no load on them, but the voltage drops very low (too low) when you try to pull any current out of them.

Volt meters are designed to NOT pull any current when they're measuring voltage. I might suggest you put a 100 ohm 2 watt resistor across the battery terminals, and with that in place, THEN measure the voltage the battery has. (The resistor will get warm.) This will draw about 100 mA from the battery which is a light but moderate load. If you still get 10 - 11.5 volts, then I would think the battery is OK and the problem lies elsewhere.

Thanks for the reply leoblob. I tried putting a 100 ohm resistor between the two battery terminals, and it still puts out 11-12 volts. This is getting aggrevating, it's a lot like chasing down a parasitic draw on a car battery (BMW tech by trade). The funny thing about this is that the LED indicators shows that the battery is charged (green battery icon), Windows says it's charging and only has 29% charge. I can select battery "properties" and it recognizes the LiIon battery type, name, and some other stuff. I've tried running a battery test using PC Doctor DOS from IBM's website, and it doesn't recognize a battery plugged in at all. Anyone else have any ideas? Does the DC/DC board handle the switching from outlet power to battery?

Sounds like the battery IS holding a charge, but... just a guess here... I would probably replace the battery anyway. Mr. Guttman pointed out that there is a logic board in there, too, and possibly that's creating the problem... ??? Replacing the battery is certainly easier than starting to take the machine apart... of course, the $$ for the new battery might end up being wasted if it still doesn't work. Hopefully someone else will have some other ideas.

My brother still has the NiMh battery, and he's bringing it Thanksgiving to try. Does anyone know for sure what controls switching from adapter to battery power? Bill??? Anyone?????????