I have had a quick look through the threads and haven't found anyone discussing this idea in detail. I hope i haven't missed it.
I have just bought a Ford e350 7.3 diesel based school bus Iím turning into an rv. There was no aircon installed in the bus and the wife says I have to get that resolved. So, I am thinking this:
Install a high output alternator (150-200A) feeding a 250Ah deep cycle battery bank, feeding a 3kW inverter and then a domestic aircon (maybe like this one - Haier 8,000 BTU 250 sq. ft. Cool Only Portable Air Conditioner with 70 Pint/Day Dehumidification Mode and LCD Remote Control-HPRB08XCM - The Home Depot
Iím no electrician, but here are my sums. The aircon claims 6.3A required, but I am told that a domestic aircon could draw up to 5 x on start up, so I need to prepare for 31.5AC amps although this seems ridiculously high and well past the normal fuse range. Nevertheless, 31.5A x 110V = 3465W. 3465W/12V = 289DC amps on startup. Nominal running should be 6.3A x 110v = 693W / 12V = 57.75DC amps which is easily in the range of these alternators claimed output even at idle (600rpm).
I know there will be loss in the system, and the output/demand of these items will be overestimated/underestimated respectively, and i need to keep the DC wires short, and the alternator wont last more than a few years, but I have also heard people running 15,000 btu aircons on 2,000W inverters, so my solution seems reasonable for good aircon compared to other solutions.
Does this all make basic sense or am I missing something?