Slight hijack, but may be useful to the OP.
People keep saying to keep the thermostat down around 50 to prevent the battery from dying.
I camp/hunt in very cold weather, have one 7 year old battery (almost time for a new one), and keep my thermostat at 68. Yes the fan cycles on frequently during the night. But I can routinely get two days out of my battery like that before recharging. And it's never completely dead. I'm using non LED lights for a couple of hours each evening, the fridge is on, occasionally use the water pump, furnace fan almost all night, and then the tiny phantom draws.
Why are some people's batteries dying after one night, or especially halfway through the night? Fairly certain my battery isn't enchanted. Other than starting out at 100% (always use a battery tender when not in use), I don't do anything special.
Recently, I camped and didn't need the furnace at all. But we did use a 12 volt TV for at least 2 hours each night, and got 5 solid days before it was in need of recharging.
What gives? Any ideas? This is an old 1987 Wilderness. So it's definitely not a super efficient system.
Edit: I should add that during those cold trips, we leave at 0500 and don't return until early evening. Like maybe 5 to 6 pm. During that time, it's just fridge and phantom draw. But we hit the rack at about 8pm. So that furnace and fan are running for about 9 hours, give or take.
