Bob, 6v deep cycles carry more amp-hour capacity than 12v ones, so stick with 6v. Costco’s Interstate ones are about as readily available and good a deal as you’ll find. I was gonna go that route, but am tired of dealing with the metal corrosion around the battery tray and the melted strap-down buckles. As the batteries age they demand more charging and that makes more gassing of acidic, corrosive condensate.
After entertaining and researching a lithium notion for months, I’m switching house bats to AGM’s. Fullriver is well reviewed, but are Chinese built and I’m trying to minimize such purchases where I can. I’ll likely settle for the good rated US Battery brand, made here I believe by Johnson Controls. I don’t mind adding water to wet cells, and my original Interstates lasted 12 years with no obvious performance issue, but the corrosion has been a pain for too long. New wet cells wouldn’t be so bad for awhile, but eventually I’d be back to the same ol’ same ol’.
At 12.7v your current batteries seem fine if they’re holding it well. Be aware that at 12v they are half discharged, many coach devices don’t work there, and you don’t want to hang around there long; keep things charged. 13.4v float charge is topped up. And it probably goes without saying to use only distilled water in your wet cells. Check that your inverter doesn’t automatically run an equalization charge regularly.
Joel
