I set out on a ride on my hulybrid bike this morning. Phone was at 45% I turned off the data and WiFi but have location on and a sports app Endomondo running to record my distance. 1.5 hrs later it was down to 10%, then at home dropped to 3 % quickly and shut off. I plugged it into my Samsung fast charge portable charger and instantly it was showing 27%. Wondering if this means my battery is starting to go? It seems fine during normal daytime with data on and auto sync. It seems when I run that endomondo app on the phone it'll drop quicker, but the odd thing was 3%, died, plugged into fast charger and instantly 25%.