Although it is a nice gesture on your part, a better plan would be to just run your generator to maintain your battery in it's mid level. Your charging converter will put the maximum amount into the battery in the shortest time when the battery is just below mid range, and you charge it to just above mid range. Use inexpensive inverters to power chargers and TV's as much as possible.
For about three dollars I have a tiny voltmeter on my battery that shows me my battery voltage as I camp. I become aware of when I need to charge, and also I am aware of how many hours I need to replace what I am using.