So, I started noticing this with iOS 7 on my iPhone 5 and I have drained it dead and charged to try to calibrate, but I really don't think there is a battery hardware issue. Battery will show 40%, then while I am on the phone doing something, it will drop to 1%. Then I plug the cord in to charge like most would, and it jumps instantly back up to 38%. Then at 22%, the phone dies. Then I just wait, turn it back on, and back to 22%. I really can't figure this out. So my question is, should I wipe the phone and re-install iOS 7 entirely? If so, is there an easy way to do this? Sorry for the noob question.