Skip the 6V batteries, they're not worth it. There's nothing wrong with them, but for the typical RV use (especially when you have full H/U most of the time), it's a bit of a waste. Go straight down to Wal-Mart and buy 2 marine deep cycles. Maintain them properly and they'll last you for years. I have 2 of them in my TT and 4 of them in my boat. Two of the boat batteries are 2011 and they get constant abuse from vibration, bouncing, discharging, etc. They're about the most affordable battery out there, and if by chance they do fail, you're likely to find a Wal-Mart near anywhere you are.