As far as using the heater it would probably only be around 45 outdoors at the coldest and would like to keep inside at least at 55. I haven't done this before so that's what I'm trying to figure out. I would guess it would run no more than 3-4 hours.
Time2, I like your style. However doing hydrometer tests are a real pain on this unit as the batteries are in a tight lower compartment.
I installed a volt meter connected to the main lugs of the elecrical panel. Cheap meter but it matches my multimeter and solar controller.