Originally Posted by NevadaNick
If you cant leave your furnace on overnight you need new batteries and not just lithium.
I actuallly did just replace all 4 house batteries. But i have fridge, ice maker and basement freezer that runs off of the batteries, as well as the "mood" lighting that we leave on for the kids, and a few other things as well. We've got more drawing power on the batteries now than the rig was really designed to handle. I'd imagine it could handle just the 45kBTU furnace just fine, but I don't want to find out the hard way.