Yup...What Fonzi said...double check the water heater and any other possible loads. The battery charger/ 12 v supply should only draw a few amps, anything 12v down stream of it may be a lot of amps in "DC", but is nothing for the 110v powered coverter to supply for all your 12v needs, including charging low batteries at the same time. Begin with your ac on low mode and switch up once its running if you have to, but your genni should be able to run the 13.5 on high all day long!
-Todd and Sherri
-2006 F250 Super Duty King ranch Diesel
-2012 Windjammer 3008w
-Equilzer 1200lb hitch