I am also referring here to Laptop battery holds charge, but won't charge any more. I may have the same problem but I am not sure, maybe DaBaer could answer me?
The battery is a replacement battery I just bought and nothing seems wrong with it. Then yesterday, although the laptop was connected all day long, I noticed the battery icon very low in the evening. Strange. Then after half an hour, laptop powered off by itself without any warning, although it was connected to power.
A few times I have tried to restart, the red charge LED went on for a few seconds, restart failed, no power, screen black, and it failed altogether.
I let it sit ("dry") for 20 hours and reconnected power while the laptop was off. The red charge led went on blinking. I charged it for some time with the lid closed. Then I could start the laptop again.
However, for a few mninutes the system tray battery icon tells me it's charging but weird numbers that change all the time: 10 hours to go, 2 hours to go, 4 hours to go, it changes all the time. Also the charge LED is steady, no longer blinking. Then after a few minutes icon shows laptop has stopped charging while the battery level is very low. When I disconnect and reconnect, the icon wakes up and laptop starts charging again, but at a much lower start level. It went from 25% to 19% in a couple of minutes and a couple of times connecting and disconnecting. Finally I disconnected and the battery stays on the same level for a long time, so it's clearly not the battery causing the problem.
It could be the CMOS battery or the connector slot, or both. (see URL above of answer posted by DaBaer earlier)
I must mention that I live in a place where it's incredibly hot and humid, or worse, cold and humid inside my house (the tropics) plus we're at the coast so there's a lot of salt in the air. I have had one laptop and one phone die on me in this place. My modem won't start up in the morning if I don't leave it on all night to keep it heated insight. It's damp, cold, rusty, salty, humid, etc. etc. inside all my equipment.
So that's just info that might make it probable that batteries wear off faster and break connection faster as well (a lot of rust inside).