The charging behavior started weirding out a few months ago (rapid discharges when unplugged, intermittent or no charging while plugged into AC) so I got a new Li-Ion battery, thinking that was the problem. Unfortunately, I saw the same weirdness.
I've now got two AC cords to try as well, and I notice that I can now charge the battery up OK, but if I shut down while still plugged into the wall, the battery will drain to zero overnight. If I unplug from the wall, the battery keeps its charge overnight. To me, that indicates the cord/brick is faulty, but I see the same behavior from both cords/bricks, so I'm not sure what's happening.
Has anyone seen this type of behavior from their laptop, or have any suggestions?