Concerning your battery charging issues what you'll need is what's called a battery isolator. We used them in the marine industry to keep the starting (cranking) batteries and house (deep cycle) batteries charged while the boat was underway.
I am an sojourner in the earth; hide not Your Commandments from me. Psalm 119:19
Here is the patience of the saints; here are the ones keeping the commandments of YAHWEH, and the faith of Yahshua. Rev. 14:12