Start the engine and it will charge the system if over an idle. Watch the AMP gage for it to level off probably 20 minutes or so. The generator should start when it gets power from the engine. That's assuming you have more than a quarter of a tank of fuel. The house batteries need the distilled water added if they are below the proper "neck" level. Adding when low causes them to loose charge so check often and only add a few ounces at a time. The house switch will operated on and off only when there is a charge in batteries.