[prndl]

Everyone is trying to be helpful but telling the OP what you have will not help them out today.

If you only have one battery it will not last the night with the furnace running. If you have enough propane I would connect the truck and use it to charge the battery(s) every three or four hours as needed. If you are where the big freeze is occurring it will be a long and miserable night but doing this but you will hopefully not have any damage. Run the refer and water heater on gas. A power outage is not the time to shop for a generator.