[Richard]

Sure. The basic premise is that every excursion below 50% capacity, and every overcharge takes irreplaceable life out of the battery. This applies to standard lead acid and AGM battery technology. Lithium technology can be taken much deeper in the SOC without harm.

First, NEVER let the batteries get below 50% charge. You will have to look up what voltage that is for your specific brand of AGM. Set the Low Voltage Cutoff LBCO on your inverter to that voltage. Better yet use an inverter charger that calculates State of Charge (SOC) or install a meter that displays SOC. One thing to be totally aware of is that the Aquahot pulls directly from the batteries, and not through the inverter. So dry camping in cold weather has the potential for takeing the house batteries to a very low SOC.

Second, Use the specific charge profile recommended by your battery manufacturer. Adjust the charger outputs to match what is recommended by the supplier.

Third, be very aware that merging the batteries while driving has two downsides. It can put a strain on the alternator depending on the discharge state of the house batteries, and the alternator does not have the same smarts as the charger when it comes to charging profile. I know you disagree, but when the batteries are merged while parked, the chassis batteries are subjected to the charging profile setup for the house batteries. The AGMs and normal lead acid batteries take a slightly different charge profile. You are likely to boil your chassis batteries if you keep them merged while plugged in. In my opinion, if you feel like you need to charge the house batteries while driving, crank the generator. Yeah, yeah, I know then why did almost all manufacturers install the capability to charge the house batteries from the alternator. Just because you can doesn't mean you should. The original question was "how do I keep from murdering my batteries?" In my opinion, given the replacement costs of an alternator, you can buy a few gallons of fuel for the gennie.

This may sound fiddly, but once you set the systems up with the proper parameters, and you adhere to the practices, very little attention is required for the batteries.

@"folivier" may have some additional input