Welcome to Android Central! I agree with hallux -- there are so many reasons that are much more likely than being hacked, so no need to jump to that very unlikely conclusion.
Charge up to 100%, then let it drain to 20-30% with normal usage, without charging in between. Then show us:
1. The main
Settings>Battery screen.
2. The fullscreen battery graph screen (which may show Awake time and Cell Signal Strength).
3. The Screen category (to see total Screen On time).
4. The Cell Standby category, if present (to see Time Without Signal).
http://forums.androidcentral.com/ge...ide-how-post-screenshots-android-central.html. You'll have to register first.
You might have to install a 3rd party battery monitor, like GSam Battery Monitor, to get the Cell Signal Strength graph.