2022 190 Heater Question

Hi Nick,  no stupid questions are ever asked here, and that includes yours.  Your furnace runs off propane only.  It does need your battery (or shore power) to run the motor of the furnace.  I normally camp where there is no electric so it is imperative to have a couple of good batteries when camping in cold weather.  I usually get 6 days out of my two 12v batteries when night temps are in the 40's and that is without any assist from generator or solar usage as I have neither of those.