Why is my battery draining to quickly?

To Scott P. and wm_alvarez,

First, thanks for responding my question so quickly . My screen currently reads ‘Maximum Capacity” at 80% but, that leads me to still ask the original question. Before I broke my screen and had it repaired, my battery capacity was at 89% and the phone lasted at least 8 hours no matter what application I used. Logically I understand that at 80% the battery will hold a smaller charge and thus seem to lose power quicker because there is less power to be had, but if it lasted 6 to 8 hours at 89%, I don’t understand why it only last 15 minutes at 80%. It just doesn’t seem right but thank you for the information and I’ll get the battery checked.