Gdetrailer-
Not going to defend Westinghouse in depth, but their <3% THD is plenty good. AND I had the same behavior from a Yamaha 2000iS which I would consider a “high quality” generator (from previous thread). Additionally I know someone with same 5er and ACs (without Magnum) that can run not just one of the ACs with their Westinghouse i4500 but BOTH ACs as long as everything is off.
Bottom line, at this point I’m convinced there is something in my particular Magnum 3012 that doesn’t play well with genny s. Just spent another 30min with Magnum support, and they’re going to research and call back again tomorrow. The big question in my mind at this point is this anomalous behavior from my inverter? (Tech and literature suggest probably/yes) Or is this inherent in the Magnum design; in which case I probably will just add soft starts, but should have chosen Victron, but too late now.