Conversion of a Single Stage Alternator
(Enabling Three Stage Charging)

Pictured at right, is a basic Hitachi 55 amp 12 vdc alternator. It is one of the standard alternators initially provided on a large number of Yanmar diesel engines. If you look carefully, it has simple modifications that have major ramifications. The internal single stage regulator is bypassed and new wiring is provided so that an external regulator may be used. The net result of this modification is to provide a proper, reliable, 3 stage charging source from your standard basic alternator. This is critical sometimes to ensure proper fit and alignment without modifying the standard connecting arm(s), attachments, or v-belt for various optional alternators that have not been specifically designed as a direct replacement for your alternator and it's possible unique installation requirements.

Some smaller vessels do not have the need or adequate room for a second high output alternator. The end result of this base modification ensures a proper charging source is available for even the smallest of systems.

For larger vessels, this modification will allow your entire system to be properly designed and implemented with full three stage charging from every source. The alternative is severely shortened battery life for those items being charge by the single stage charging source.

Modified Single Stage Hitachi alternator allowing for 3 Stage External Regulation


When you send us your single stage alternator for conversion, we will return to you a total package consisting of your modified alternator complete with a new wiring harness connected to a 3 stage regulator. The only optional items that should be considered are alternator & battery temperature sensors and a transient spike protector.



Please contact us for full details and to ensure your system is capable of conversion. Unfortunately, some alternators are unable to be modified due to manufacturer intentionally imposed limitations.For those alternators that are unable to be converted, are too worn (near end of life cycle), ... the alternator shown on the right, is our ZRD 3-stage Externally Regulated replacement for Hitachi alternators. Full details may be viewed by clicking on ZRD Hitachi Replacement or the picture shown (externally regulated 'sibling' version). It is a New (not remanufactured), 3-Stage, Externally Regulated, 3.15 inch dual foot mount alternator with an output of 12 vdc - 94 amps.

ZRD Hitachi Replacement, 3 Stage, Externally Regulated, 12vdc - 94amp, 3.15 inch foot mount Alternator