The key is shutting off all the other loads at the panel, turn on the fan only for a few minutes, then switch it over to AC. I know it is pretty marginal, but it has always worked for me. The battery charger is a big current hog. There isn't enough current to start both the compressor motor and the fan motor at the same time.
I would really like to convert it to propane, but I'm afraid the small difference in power between gasoline and propane would be just enough to cause it not to work. Has anyone tried to start the AC with an EU2000 converted to propane?