Abstract: An alternator rotor for use in an internal combustion engine having a primary rotated crank shaft. The alternator rotor comprises generally cylindrical rotor housing and a balancing member secured to the rotor housing. The rotor housing is mountable to the crank shaft of the internal combustion engine such that rotation of the crank shaft causes rotation of the rotor housing along an axis of rotation generally parallel to the axis of rotation of the crank shaft. The balancing member includes a moveable mass that is capable of movement generally about the axis of rotation of the rotor housing in response to the rotation of the rotor housing such that upon rotation of the rotor housing the moveable mass moves about the axis of rotation of the rotor housing in response to the both the centrifugal force applied to the moveable mass and to the unbalanced forces generated by rotation of the engine.