Hi, My iPhone 4S battery all of a sudden started to drain quickly, so I checked usage times and standby, which are almost the same. Over night, that results in 25-30% drain. What I have tried so far: - Flight mode - Turn off notifications - Turn off location services - Turn off Bluetooth + Wifi - Quit all apps (+ open and quit all apps once more) - Restart/Hard Reset - Exchange SIM card - Calibrate battery by letting it turn off itself - Reset all settings (+ erase all data) - Restore from Backup - Restore from DFU mode - Restore and set up as new phone (+ no service/function activated during initial setup + no additional apps installed + not synced) - Redownload firmware to make sure it is not corrupted (both in iTunes and from direct links) No matter what I did, the usage time is still about equal to standby, and the phone is dead after about 16 hours. I don't know what kind of process is running in the background, but it is strange enough that it will show more than 15 hours of usage by the time the battery is down to 1%. Any other advice what to do? Thanks.