I've heard that it's always unwise to run the MBP off the AC Adaptor, so I'd always plan to have it in... But the thing is I plan on taking the MBP to school every day, (I'd probably take the adaptor with me) and alot of the time, unless the battery ran out, I'd have it unplugged. My main question is, how long to you think my battery will last if I do this? I need it to last me AT LEAST a year, and even when the battery is faltering, will it still be able to run at full force when plugged in? Or will it's power be halved like if the battery wasn't there?