Originally Posted by homeless
Thank you for the suggestions and help. I did cut the 110 wire from the Cpap and put a liter plug on the 12volt side and spliced in a receptacle in next to the bed. I have two new deep cycle batteries and I run the machine for eight hours. Batteries seem to not have been effected? I say that because the test panel still shows batter 1 and battery 2 still looking good or have same number of lights. I do wonder if I will have to run the engine for eight hours in order to put back the charge I used????
What you are seeing is normal. We have 2 batteries and can go at least 2 full days without charging. I let mine go down to about 11.8 volts.
So, we run the cpap for 16 hrs, the Tv for about 8 hrs, the 12v system for the frig, hot water, CO2 and propane detecters, the lights and we run a 12v exaust fan at leasr 4 hrs every day.
You would certainly not need to run your engine for 8 hrs after running the cpap for 8hrs. Since the alternator puts out 14.1 to 14.5 volts, I would guess running the engine 1hr every 2-3 days might get you by. You'll just have to do some tests.
Your engine will burn about 1 gal an hr idling. A generator just powering a battery charger, will burn about 1/3 gal/hr. But the difference is going to be the output of the charger. If you have an older single stage charger, its only going to put out 13.6v. VS 14.5v by the engine. So in theroy, it could be cheaper to charge via engine than generator.
This interests me enough to some day perform an experiment.
Just remember, while charging, your lights will indicate a fully charged battery. It will take perhaps an hr after charging before the batteries will equalize and show a more correct reading.