Please check whether Bluetooth,Wi - Fi,GPS,NFC,Screen rotation,Tethering and Portable Hotspot is turned on when not in use.Also please check Power Saving or Ultra Power Saving Mode (If available).Auto Sync of E - mails,App data etc will drain battery.Network Fluctuation also drains battery.Auto Sync of E - mails,App data etc will drain battery.I would request you to follow the standard charging procedure(i.e. charge a fully discharged the battery in Switch - off mode up to 150 minutes).Please also check software update.
