S Series The S series of 6 phase alternators offers incredible output in a compact and durable package. Highly efficient, these units use less horsepower per Kw of power produced than conventional 3 phase alternators. 12 diodes, twin rectifier plates and outstanding airflow ensure long service life, even in severe conditions. NOTE: This unit has a self exciting internal voltage regulator that does not require anything to be plugged into the alternator. This alternator is also available with a serpentine pulley. An alternator of this amperage may experience belt slip when driven by a single V belt.