The Northstar Battery website says up to 80% discharge not full discharge and for up to 400 cycles. The dealer is misinformed and I suspect like every battery claim it is rather optimistic in that with every discharge a battery loses some maximum capacity. AGM batteries are still subject to outgassing and that is why most, including Roadtrek, put the batteries in vented boxes usually below the floor. What kind of controller is handling a mix and match of 12V and 24V battery setups? I'd ask for references and names of other B owners that got a similar setup from that dealer. Something is just not adding up here. An 8 year warranty on everything is also a questionable offer. Does it negate Mercedes Benz, Roadtrek and all the other product manufacturer's warranties? 8 years quite frankly is beyond reason. I hope you know what you are doing because it mystifies me. I am aware of the agony some DIYers are going through figuring this out, Roadtrek has gone through multiple corrections and I know a little about what Advanced RV is encountering and discovering. It is not as simple as just adding batteries and connecting wires.