Wow you read my mind on several questions. Combining several units, the beep! They are all 120volt 20 amp imput. I think I saw somewhere 1985 watt load at full capacity. They are not XL series. Too bad. You can still use external batteries no? Have to splice/modify? I do have a well pump and it does not look like they can be used for that. So you would use a dc battery charger/alternator to charge the batteries not an AC generator and use the internal charger? Would you run several units off one large battery bank? I did a little research and it would seem I would need to get a 40,000 watt generator to run all these and charge them at the same time. That seems crazy no?