Quote Originally Posted by dusty2221 View Post
I'm coming to conclusion that amp/hours can't be argued, and 2 6v are simply the better way to go (size permiting).
How so? You quoted that a pair of 6V golf cart batteries provide 180-220 AH whereas a pair of Group 27 marine deep cycle batteries provide 230 AH (at least the ones at costco do). And they are smaller than the 6V batts.

Also, I think you are going to have to upgrade to the ProSport 20. As David has pointed out, you need a charger with an output of 10-13% of your total battery AH in order to desulfate the batteries during charging.

I currently have a two battery set up (one starting and one stereo) but fortunately, I bought the ProSport 20 in case I added a third battery in the future. Sure enough, I went from two amps to three at the end of last season so I am going to add a second stereo battery this winter. With that, my charger will be below the 10-13% recommended output for the 230AH worth of stereo batteries (not even counting the starting battery) but as long as I don't discharge them too deeply, I think I will be okay. At David's suggestion, I will probably add a switch to the starting battery charger lead so I can take it off line when needed and direct all 20 amps to the stereo bank.

Al