The first blower exhausts from the aft end of the engine space and there is a passive inlet pipe aimed at the stock 80 amp Hitachi alternator. We just added a 210 am Balmar and have a bigger fan pulling from the area around the alternator's fan vanes. Our house batteries can demand everything the alternators can give them when the batteries are drawn down. Haven't put the new rig to a full test yet. Extra ventilation is deemed necessary.