So, I've had my late 2008 MBP unibody for more than 2 years (bought it refurb from Apple) and loved it. But I think my battery might be dying. It has over 300 cycles on it and is doing this weird thing. If I turn on the laptop on a full charge, the computer shuts off at around 85%. It says service battery in the battery icon. It seems though it doesn't shut off when the computer is sleeping. It was in sleep mode all of last night, and is at 65% and was still going strong. It got to 55% then shut off. The computer doesn't shut off when on the power adapter. Anyway, I don't have the funds to buy a new battery so I'm looking for some tips on how to extend my battery life, and not have it shut off as often. Pretty much every time it shuts off at around 85-90% from a full charge.