I agree with Bill,
I've had a Xantrex on Koesh for years and have had excellent luck with the charger. It's been gentle enough that my cheap automotive batteries have lasted me for eight years so far. Make sure that when you wire it in you use proper Marine grade, tinned wire for all circuits. My boat had some of the shore power wired with solid core that I'll be replacing with the new harness I'm making up over the next year.
Doug Marshall