Alternator Regulator: Notes

The voltage regulator limits the alternator output voltage by controlling the amount of the alternator field (rotor) current. The alternator maximum current output is limited to a specific amount by the basic design of the alternator; because of this feature, no current-regulating device is required. Alternators are available in many different current outputs depending on the electrical requirements of the various vehicles.

On some charging systems a field relay is used along with the voltage regulator. In a circuit with an ammeter, the relay is used to open and close the field circuit. Where a charge indicator light is used instead of an ammeter, the relay controls the charge indicator light as well as the field circuit. The field relay may be mounted within the same housing as the voltage regulator or it may be a separate unit.