Thanks for the info on the differant battery types, here's some new questions, Where should I look for a deal on the agm batteries? Do you folks find the local boating store as cheap as anyplace or are there deals on-line. Is one manufacturer better then others? And finally, my guest battery charger "hummms" all the time I am plugged into shore power, is that normal or should it shut off when the batteries are fully charged? thanks, jack