Tank Heaters

[cloud william]

We just got back from some cold weather camping in near to below freezing temperatures. We have the DRV factory installed tank and elbow heaters, and every time we use them we notice that the current draw is only 1 or 2 amps above whatever else we have on at the time. As far as we know our tanks haven't froze, but, given the size of the tanks, this seems like a really small current draw to keep them from freezing. What kind of current draws are others out there seeing when they have their tank heaters turned on?

[Fulltimer50]

The heaters are operated by 12v DC. That may be why you dont see much AC current change.

[cloud william]

Yes, the tank heaters do run off the 12V power. Still, when connected to AC shore power, if turned on the they would cause a draw off the AC inverter/charger to keep the batteries fully charged. I believe this is the 1 to 2 amp draw I see on the power monitor. I'm still surprised, given the combined size of the fresh water, grey water, and black water tanks, that this is enough energy to keep that much liquid, even if it starts out relatively warm, from freezing in really cold temperatures.

If the current draw really is that low, then turning the tank heaters on while boondocking seems reasonable, which is another question I had. Also, in the event of a shore power failure that would cause the inverter to kick in for hours at a time, it seems like you could keep up with this current draw by running the generator in the mornings and evenings to keep the batteries topped off.

I guess the real question I have is how do I know the heaters are working properly, or are even working at all? There doesn't seem to be any indicator anywhere to let you know what the heater status is. Given the severity of a tank heater failure in really cold temperatures I'm surprised there isn't any indication.