Gerry I don't have the Danhard but from older posts I don't think the problem was with the batteries as much as it had to do with starting the AC. If I remember correctly, this had to do with running the unit while driving. Greg in Austin would be the best to PM about this and he did make several post about his new Danhard. Pretty sure he is running twin 4-D house batteries. Obviously a larger generator like the 2400 w BW is running would help. But running the Danhard on battery power requires a large house battery system if you plan to run on "battery only" (no shore power) and even a large battery like a single 4-D battery won't last too long. There are some issues about startup using the standard inverter as well. You might search "Danhard" in the site search engine but Greg would be the best to contact.
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer
I have on 4D battery, when using a coffee pot (this is not the one sportsmobile sells, but a 8 cup thermal carafe only uses power while making coffee) it will deplete my battery 10% or 1/5 of my usable power. see attached pdf for details. That should give you a ball park of typical power usage,
If I get a chance I will collect some data on the microwave and water heater.