The furnace blower fan is a 12VDC item and normally draws around 6-8 amps which is a hugh battery drain. Each automotive bulb you will have in your light fixtures draw around 1 AMP each. Your ceiling fixture usually have two bulbs in it... It all adds up pretty quick...
I always wanted to get a solar panel around 140WATTS to supplement my battery system upgrades so I could get the use of the sun light during the day to help keep the batteries charged up. Presently when I am camping off the power grid we can make the one day/night power drain off the batteries pretty good but have to re-charge again the next morning so we can do it all over again the next day/night battery run. Using the small solar panel during the daytime should really help us here and maybe I can go two days without recharging my battery bank.
It all takes a little planning. I have stated many times in my posts you just cant do one thing to be successful about it... Got to be a system plan to be successful... Just might get dark on you when you least expect it to without some pre-planning.
Roy and Carolyn
I claim Horse Creek Country in Southern Ill - Momabear is from North Texas
We live in King George VA
RETIRED DOD DOAF DON CONTRACTOR Electronics Tech 42YRS
"We're burning daylight" - John Wayne
2008 STARCRAFT 14RT OFF-ROAD POPUP with PD9260C and three 85AH 12VDC batteries
2010 F150 FX4 5.4 GAS with 3.73 gears - Super Cab - Towing Package - 2KW Honda EU2000i Gen
K9PHT (since 1957) 146.52Mhz
"We always have a PLAN B"