[KeithInUpstateNY]

I've had good luck with the Everstart MAXX group 29DC off the shelf at Walmart. At various times they have come with 18 or 24 free replacement, though I noticed recently they didn't have any warranty, which isn't unusual for deep cycle batteries. If you are a Sam's Club member, the Duracell AGM batteries have performed well, despite the charge controller profile problem. I now have them at my cabin connected to my solar panels. So I would expect the Duracell lead acid batteries to do well too, and they currently have a one year free replacement. I have stuck with 12 volt batteries in parallel (I mostly boondock) for the very problem you are facing, fear that one 6 volt golf cart battery will fail prematurely and I'll effectively be stranded with no battery.