I have Early 2011 15" Macbook Pro. I've been using it for College since 2011. Now the battery is starting to die. I am not too sure if my warranty is still alive nor if I am able to get a free replacement. My plan B is if I am not able to get it covered without charge I would have to buy a new battery replacement. Im aware it's 77.5 wh but would like to know if you can replace the damaged one with higher watt hour battery? Is that possible?