If I run the little stuff, lights, TV DVD player etc. but no microwave on the 800 watt inverter, how long would it take to drain two 6 volt batteries? If I run a small 1K gerenator during the days will that be enough to keep the batteries up? Don't really watch too much TV on my trips and hate to run the installed 4K genreator, burns too much gas and is noisy when I'm inside the trailer.