I have a new MBA with 4G memory (250g hd). When I first got it, and calibrated battery, if I unplugged the computer, the initial time the battery showed remaining was over 7 hours (this is before I did anything). Now, I have tried everything including recalculating, and it is giving me only 3.5 hours remaining. And it drains quickly even without doing anything. I cant seem to figure out what to do and why the battery is suddenly showing half capacity. Thanks in advance.