T23 strange battery charging behavior

[RealBlackStuff]

Got a T23 2647-8NU (with Windows XP/SP3) with strange charging behavior.

It has the following symptoms:
- Battery wouldn't charge. Resoldered inductor under the KB-mouse buttons, it now charges again.
..But even at 100% the yellow charging LED is still on??? but the battery is full.
..(I checked all other regular suspects as well, and resoldered the other inductors and 3 quartzes.)

With the (charged) battery in:
- when I press the power button: fan, CD and HD start whirring but it shuts down after 5-6 seconds.
- repeated many times, same symptoms.
- when I then just insert the AC-connector: fan, CD and HD start whirring but it shuts down after 5-6 seconds.
..(I checked the AC connector and cables, all OK).
- leave battery and AC in, press Power, every 2nd or 3rd try it boots normal.
- With Windows running, I can take AC out, Windows continues to run normal (at reduced battery settings).
- With Windows running, AC in, I can take the battery out, Windows continues to run normal (but at reduced CPU settings).
- put the battery back in, everything still fine and back to full power.

PC-Doctor does not find anything untowards. RAM replaced, same story.

Question: is this an I/O board or a motherboard problem?
My suspicions are hairline cracks in the mobo, from carrying the laptop at the left front corner.

[Paul Pennington]

What voltage are you reading on the battery? Have you tried more than one?

--Paul

[RealBlackStuff]

10.8V.
Tried two other known good batteries, same result.

[RealBlackStuff]

Anybody have more insight?

[rkawakami]

Best guess would be that you are looking at the motherboard for the source of the problem. The ADP3806 next to the inductor you re-soldered is the battery charger controller. The MAX1631, just to the left of the keyboard connector appears to be the 5V/3V power supply controller. From looking at the datasheet for the 1631, there's a shutdown control signal, as well as a current-sensing monitor (i.e. voltage measuring) which can kill the power if it exceeds whatever limit has been programmed. There's also a TB6808F just above the HD connector. Searching for that part number seems to indicate that it's the main power supply controller. I have not been able to find a detailed datasheet for that part.

ref: http://forum.thinkpads.com/viewtopic.php?t=37956