RV heater and battery consuming

[Minh Nguyen]

Hi,
We have 2020 Thor Freedom Elite 22FE. We never dried camp until last week and always had full hookup at the camps so we didn't pay much attention to how/from the heater draws power from. We assume that it either it from the shore power or from the propane tank.
So last week, We just dried camp one night for the first time and it was cold at night so we used the heater pretty much on and off , with the thermostat of course, during the night in the next morning we got an alert that the battery was low. We barely used any lights or other things other than the water pump. I was pretty sure somewhere in the RV, some devices always draw power from the coach battery but not to the extend that it made the battery went down to the level that it had to alert us.
So do you think the heater somehow consumes the battery as well for whatever it has to? or it is time for me to look at the battery condition?
Thanks.

[ducksface]

Even when new, my little 100amp dual batteries(200amps total) are not quite enough to keep the heater FAN going for more than 8+ or so hours when we add in two quick showers and a couple of flushes.
Your heater FAN is 12 volt and runs off of battery.

[Minh Nguyen]

ah, the fan I totally forgot that the fan needed there to spread the hot air

Thanks for your response.