Unless you specifically rewire your trailer to power just the fan with the battery you will have other things that are powered while the battery is on. IE: carbon monoxide, propane leak detectors, radio memory and others. It has been my experience that just these things will kill the battery while the trailer sits. Two nights on one battery may max out your battery without running the fan at all depending on if you run the furnace, how many lights you use and so on...Everything in the trailer runs on 12 volts except your refer, water heater and television...
B.O.
