My Mercedes diesel RV gets 16 MPG.
I have two Mazda Miatas with AGM batteries that were still working at 16 years. Replaced them because I thought they just can't last the much longer.
Dry camped a pop-up for a month. 12.8 VDC start to 12.4 VDC after one month.
Only used group 27 Optima AGM battery for water pump, LED overhead lighting and USB port to charge phones.
Would use lights while eating/cooking/cleaning. Reading lights were AA powered puck lights.
Converter had some parasitic draw that I was never able to figure out so put a marine grade battery switch to completely disconnect battery when not in actual use.
Would leave the overhead LED lights switch on and when lights were needed or water pump was needed, would use the battery switch.
Propane refrigerator needs no 12VDC to operate. Used catalytic propane heater that also required no 12VDC.
As you can see we were ultra conservative with 12VDC power.
Battery still going strong at 6 years when we sold the pop-up
Now very interested in a true deep cycle to replace automotive battery that Mercedes puts in their vans for RV power.
