The charger is already set to run off the generator. If you want to charge the house batteries faster you will need a portable battery charger. Use an extension cord to run from the generator to the charger and then connect the charger to the battery or batteries, as the case may be. Just remember, that too high a charge rate will cause internal problems with the batteries and will kill them faster than a slow steady trickle charge. Personally I would not do this except in case of an emergency. The generator & charger are designed to give you the best performance and extend the life of your batteries.