The solar controller charges the batteries (house first, then chassis) even with the mains off, Dale. But they won't overcharge. I rely mostly on the solar while the coach is parked in "storage" next to my house, only rarely plugging in when I have an air dryer going onboard, etc., or dreary winter weather limits solar input.
If you had to add a gallon and aren't exaggerating, that's not good and your house battery life has been at least somewhat compromised. Just parked by the house on solar, I check and add distilled water at least every few months; but it's usually only one to three cups for 4 units. My batteries are 10 year old factory Interstates, only now showing signs of weakness, so I musta done something right.
If you feel you can't maintain them routinely the old fashioned way, then perhaps Dick's ProFill method is best for you. I grew up on a farm and was taught maintenance from the get go, so it's no big deal to me to manually top off 6v. batteries every so often. With that attitude built in, I find it hard to spend what they're asking for autofill devices. But to others, the investment is worth it.
Joel
