Might be something to do with an app you are using. Myself, I had a similar issue and I got an app called BetterBatteryStats which helped me pinpoint it to it being Light Flow preventing my phone from going into deep sleep mode, draining my battery pretty quickly. Got rid of light flow and my battery is lasting quite long. Been off the charger for over a day and a half and I'm at 59% battery still (yeah, really haven't used it much except to make a few calls, some texts, some brief browsing, and checking emails. Drains quicker on the weekends). Tap the battery graph and see if your phone is failing to get into deep sleep, or is awake for the majority of the time it is on. Then use BBS to determine what exactly is keeping it awake.