The last couple days I've been monitoring my battery usage. 2 nights ago, I fully charged my iPhone and played with it a little before going to sleep with the phone showing "30 minutes of use-time and 30 minutes of stand by". When I woke up in the morning, the usage time was at about 1.5 hours. I was certain that I had closed all the back-ground apps. No app was open. Same thing happened this morning. Last night after I fully charged the battery, I turned it off altogether and turned it back on, double-checked no app was running in the background, and didn't use it for another minute. I checked the phone as soon as I woke up, the stand-by time was around 7 hours and the use-time was 1 full hour. My iCloud auto-backup was turned off by the way.