Also remember that these lead-acid type batteries love it when they are getting little bits of charging often. They hate it when they have to sit long periods of time either idle or being discharged deeply. This will shorten their life.
If they are idle a lot, they will grow little stalagmites and stalagtites from plate to plate, eventually shorting themselves out.
I plan to put a solar panel on mine with a charge controller module at some point that will keep the batteries very happy. Trickle charger does the same thing if you have a plug.
