I have been running my Thinkpad T20 for a few months now, all was running very nicely until the other day :(
I've been using a car laptop adapter running it at 16v. All of a sudden Windows popped up with the dreaded message "the battery is critically low, blah blah blah". The adapter wasn't charging the laptop. Checked the output and it was giving 11.5 to 11.9 volts. Basically an alternating voltage between that range.
I've tried charging the laptop with the geniune AC adapter and nothing! No power is in the laptop at all I think its simply ready to break up for bits now as to replace the laptop motherboard is basically out of the question.
Ahh well.... time to start researching into the major area of building you own car pc from scratch.