Last weekend dry camping our battery got sucked way down and basically was useless by the end of the weekend. We have converted to LED interior lighting and were unable to use the furnace because of the lack of power. Today I noticed the exterior electric element switch on the water heater. does the electric element work on the DC side as well as the AC side? If so does anyone know what the draw is? Trying to figure out the issue as the battery is fully charged now after a few days at home. I unplugged it and turned off the switch and the water heater ignited so I am a bit confused as to the electric element.