Ok, so i have a IBM R51 and the bay where the battery plugs in will allow the laptop to run from the battery, but not charge it.
I know the battery is fine because i tested it in a friends.
Here is the kicker, in my laptop, the back bay where the battery usually sits, will not charge, but if i take the battery out, take out the keyboard and use the charging point at the very back of the CD ROM drive bay, it will charge. Same adapter, same battery, same laptop.
Ive taken the motherboard out and had a look, there is no sign of damage on the back bay port, ive reseated all the cables internally, but im fresh out of ideas why it wont charge, it used to!