Not sure why this is but if I leave my 5s charging overnight and unplug it after 6-7 hours, its at 100% and the battery will last for quite awhile. If I charge it for 8 hours or longer, it will immediately drop from 100% to 99% once its unplugged and doesnt last as long. Like today. Was plugged in for around 9 hours. Unplugged it an hour ago, it dropped to 99% right away and now its at 89% after only 31 mins of use. Yesterday, it was still at 85% after 3 hours off the charger and 45 mins of use. WTF?