T22 thinks it's always plugged in

[ohthinker]

One of our T22s (we now have two) seems to think it's always connected to the power adapter.

It's running non-factory Windows 2000 Pro. The machine came to me with a wiped disc and I installed a full purchased OS version. I didn't try to use the restore CDs, so the setup isn't 100% standard IBM. (I don't think I ever installed battery maximizer, for example.)

This isn't the machine I use regularly, it's my GF's, so I'm a little vague on some of the details, sorry. She complained that the computer "wouldn't turn on unless I plug it in." When I tried to boot it on its own battery, I got "190 Critical Low Battery Error."

She tells me that for some weeks now, the battery capacity has been poor. The battery icon would drop abruptly and the computer would complain of a low battery in just a few minutes of use. This battery is only 2 years old, but it was a NOS IBM battery when I bought it, so its real age is probably 5-7 years - a fairly old age for a lithium battery.

I swapped in the battery from the other T22, also old but serviceable, and now the problem machine boots. It seems to be charging the spare battery. It's gone from 44% to 65% in the last half-hour or so, with the machine on. Hovering the cursor over the battery icon says "1:27 to charge completion."

However, when I disconnect the power adapter, the usual beep doesn't sound, and the plug icon next to the battery in the Windows 2000 taskbar doesn't change. The screen brightness drops by a small amount, but there's no other indication it's been unplugged.

After the machine is shut down, the orange/yellow battery LED on the hinge remains on. That's normal, but something else is not - when I pull the adapter plug after shutting down, that LED STAYS on! Formerly, it would go off when the machine was unplugged. Again, the machine seems to think the machine is plugged in, even when it isn't.

When I remove the battery, the "stuck" orange/yellow LED goes out (no surprise).

I tried the power adapter from the other T22 - same result.

I'm hesitant to try the apparently bad battery in the known-good T22 - I've read that a bad battery can damage the charging circuit (which may be what's happened to the problem child here).

The problem machine seems to boot and run fine with the battery out.

From reading other posts here about battery charging problems, my best guess on this is that the problem T22's charging chip is kaputt. What do you experts think?

Is there any way to hard-reset the T22's charging logic, to see if that helps? Should I try removing the CMOS battery and waiting a few hours?

I'm not really capable of board-level work with SMDs, so if the charging chip is the problem, I'm afraid the solution will have to be another mainboard. It would help to avoid that expense right now.

What do you think, will replacing the apparently defective battery at least let her carry on using the machine even though it doesn't recognize the absence of an AC adapter?

Or will that cause some damage, such as overcharging the battery?

Thanks for your help with this!

[tfflivemb2]

You might want to install Battery Maximizer, which you said that you hadn't, and then run the battery through a full cycle. Sometimes with will reset the battery, and the laptop's reading of it as well.

[ohthinker]

I'll give that a try. Thanks.

[jronald]

Also, all bets are off with and aftermarket battery. They just dont seem to work as well as the OEM.

Ron