If you are young and your back is in good shape you can live with ice chest. As you age those 60 pound ice chests are going to get heavy. Eventually you will purchase a compressor fridge. Ordering your shell pre-wired for two solar plugs and two 12 volts ports will save you money in the future.
The biggest reason to order the auxiliary battery system is the compressor fridge and furnace. Most of the front loading fridges draw 4-5 amps per hour. The portables 2,9 - 4 when they cycle. Our Engel draws 2.9 when it cycles on. Averaging 1.5 per hour over 24 hours. One 80 amp hour battery gives 40 usable amps as your 12 volt devices wont run when the voltage drops below 12 volts. So at a 4 amp per hour draw one 40 amp battery will last 10 hours. Dark hours in winter about 14 .
If you run the fridge and the furnace both will stop working at about 3 am (I know from personal experience). Buy two batteries.
These two devices are reason you need at least 150 watt solar panel on the roof. They charge at 5.1 amps December 22nd and 9.1 June 22nd.
An easy way to determine the need for one or two battery's is to add up the total number of amps. Divide into 40.
