The 650 does do some strange things when charging.
I use a iGo system (
www.igo.com) with an A97 tip. If I charge it until the red light goes out, it shows a full charge, but rather quickly drops a bar. But lasts for a LONG time before dropping the 2nd and 3rd bar.
If I charge off the PC (always on, NO sleep mode) it lasts much longer before dropping the f1st bar.