Greetings! First post here; looks like there is alot of great info. My wife recently purchased a coleman taos camper. Unfortunately, we are already trouble shooting electrical. When we purchased it, the interior lights worked using the 12V battery that the original owner had in there. Shortly after our purchase and while the camper was in our driveway, we began to hear a beep emanating from the inside of the camper. The next time we opened the pup up, nothing worked. We then tested the 12V battery and it was dead. We bought a new battery (Interstate Deep cycle) but nothing is working (interior lights, furnace fan, LP warning system) until we hook it up to our house 110V. Then everything works fine (kill switch works also). New battery is testing fine and the 30A fuse on the pos side is not blown. Is there an internal fuse? Can anyone shed some light as to what happened b/t our purchase 1 month ago and now? Any ideas on what the beep was? I've read that the LP system beeps when it detects leaking propane, but I did not see that this device responds when the 12V battery is low.. Thanks for any help.