Under System Settings > Battery it shows you recent stats.
While you're in System Settings. Tell us your Data usage. An app could be using a ton of data in the background.
Also are you clearing cache correctly?
These are the proper steps:
Step 1: power your bionic down
Step 2: hold volume up, down, and power simultaneously
Step 3: use the volume down to navigate to "recovery," use volume up to select
Step 4: you will get a screen with a triangle with an exclamation point, next to an Android. Press volume up and down simultaneously
Step 5: use the volume rocker to navigate to "wipe cache" and use the power button to select.
Step 6: after it has finished, use the volume rocker to navigate to "reboot system now" and use the power button to select.
Step 7: say "TA-DAA!"
You should only do this once. Not every 3 hours. You're phone will not get any better if you constantly wipe your cache. It is a one time thing, not a 5 times a day thing.
Also if you're still having trouble try using the Smart Actions app to help save battery life.