One final check, disconnect the battery feed from the generator and then jump it to see if it will start. Sometimes the battery draw is too substantial to allow the juice to get to the appliance.
Also, at 6.5 volts, it sounds like only one battery is connected to the genset. Check your connection at the battery end to see if the positive/negative feeds are off two separate batteries that are jumpered.
2004 Pace Arrow 37C
2005 Honda Pilot Toad