I bought one of the Champions for running the sump pump in the stick house when the power is off for extended periods. $299 at TSC.
Is it anywhere near as quiet as the Yamaha 1000 inverter genset I use to charge the batteries when dry camping? No way!
But it's a darn site quieter than most of the construction site gensets many of the other campers at the USFS campground where I go most often use.
In the Summer of 2012, we had a nasty storm (derecho) that knocked out power for 9 days. Temps were sweltering. We moved into the TT and used the Champion to run the AC. Darn glad to have it!
Wayne
