An improved regulator system is disclosed for controlling a field winding of an alternator to regulate the charging of a battery. The improved regulator system comprises an internal regulator mounted onto the alternator. The internal regulator has an internal regulator control circuit for monitoring the battery and for controlling the field winding. An electrical connector actuates the internal regulator to regulate the output of the alternator in accordance with the internal regulator. The electrical connector enables an external regulator to be connected to the alternator thereby bypassing the internal regulator to regulate the output of the alternator in accordance with the external regulator. The improved regulator system facilitates the connection of an upgrade external regulator with the internal regulator functioning as a reserve regulator in the remote event of a malfunction of the external regulator.