15 - 30 Minuten
the battery was at a weak state only holding about 4 hours of charge, only 1.5 when listening to music or watchin movies. i had it for almost 4 years and 1123 cycles later, it was about time to change the battery.
the repair was fast and easy, easier than apple wants you to think. its as simple as removing screws and taking the flex cable out.
make sure you dust out the area and do not touch the motherboard when removing the battery.