First off, take your battery to Auto zone and have it load tested. I've seen brand new batteries that were bad. Proceed to the next step if the battery checks out good:
If you have an amp gauge, disconnect the positive post of your battery and put the leads on the positive post and the cable. Shut off all of your circuit breakers, and turn off everything in the RV and turn the breakers back on one at a time. If you have a short, the amperage will go up when you turn the breaker on for that circuit. This will help you isolate where the problem is.