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 than conventional 3 phase alternators. 12 diodes, twin rectifier plates and outstanding airflow ensure long service life, even in severe conditions. These units are available for a broad range of domestic and import applications in 170, 240, or 320 amp configurations. The 240 amp model offers the best balance between peak output, and output at engine idle RPM. Installation Notes: 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.