Tonight, I went somewhere that I turned my phone completely off for about 5 hours. When I returned home, and promptly turned my phone back on, I noticed that instead of the 62% it had been at, it was shockingly at 1%. I know it was it was completely off because I was greeted by the Apple logo when I turned it on. It would have made sense if I had left it in standby for those 5 hours, but I made sure to completely turn it off. Any thoughts of how it drained when it wasn't even on? Makes me more strongly consider to upgrade my iPhone 6 this year to a 7+. Edit: I just put it on my charger, and it instantly changed the percentage to 59% without any further action. Really makes me uneasy.