My thinkpad 420 battery is not charging. So far I have done following.
- Put another battery in my thinkpad and it is charging perfectly.
- Opened the defective battery and checked all three sets of 2 cells each (it is a 6 cell battery) and I got reading on voltmeter between 3.95 - 4.05 on those sets and all 6 cells together read 11.8.
I don't know if I can suspect the board inside the battery. Please guide me. Although I have bought another battery but I want to learn something by repairing this battery. Please guide me.