I got a macbook pro 15" mid 2010 and I have noticed in the past few months that my battery life is way low, never charging to more than about 3 hours of life. I had this issue last year and turned out I had a document in my print cue the was taking up a ton of CPU but this time I have checked the CPU and it is fine, i'm only using 3%. I have all programs ended except safari, screen brightness and keyboard lights way down. I just want my computer back to its original 7-8 hour battery life. Is that possible? Do I need a new battery?