@cyi1: Before going to bed, start an xterm and run 'top'. Look for anything using CPU. You should see only Xorg at the top, with some 1-2% CPU (and that is only because it's busy showing the activity of 'top').

I had 'pulseaudio' running with 18-20% CPU the other night, for no reason (I wasn't running anything that sounded the speakers). That killed the battery over night. A 'kill' on the pid(s) of the offending processes, if any, should prevent overnight battery drain from CPU usage at least.