Regardless of what it costs be sure to only run the genny with a decent load on it especially if you are just going to run it for 30 minutes. I usually run the AC when running the genny just for "exercise/maintenance"which is good for the AC and the converter is working as well. Once the AC has warmed up/cooled down I turn on the water hater while watching the voltage levels to insure they don't drop too low. By putting the genny under load it get hot enough to cook off the moisture that builds up in the crankcase. Bottom line, a genny will run better and last longer if it is always run with an adequate load.
:C
