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  • **NEW** 90A Hitachi Replacement Externally Regulated Alternator

    $319.99 $299.00
    Please enter your alternator belt width and engine brand and model number.


    I Do Not Ship Alternators Internationally


    IMPORTANT:  All CMI Alternators are hand built and may require a 2-3 week lead time.

    The CMI-90-ERH: 

    For the first time ever I am offering a sub $300.00 externally regulated alternator. In order to bring better value to our customers we're using custom castings/frames designed as a drop in replacement for the very common Hitachi 3.15" saddle mount /dual foot alternators such as the LR180-03C Hitachi alternators.

    Because we can share internal components from this type frame, on other alternator frames we build, we can save on manufacturing costs by buying in bulk. 

    We start with the finest aftermarket & OEM parts we can source & then build these from the ground up as a better & more cost effective alternative to the stock Hitachi internally regulated alternators found on most Yanmar marine engines. You will not find a better price, or quality externally regulated medium duty alternator anywhere.

    WARNING: In order to keep costs down these alternators are for use on DIESEL ENGINES ONLY. They are not spark protected as is required for a gasoline engine.

    External Regulator:  If you select the drop down menu you will see that I can package this alternator with a Balmar MC-614H or ARS-5H regulator or with these regulators and a temp sensor. I recommend setting the Belt Manager feature to level three to five when setting up the regulator. This alternator is capable of 110A of output when cold and a 1/2" or 3/8" belt can not handle that. I strongly recommend using a temp sensor and Balmar regulators with this alternator.

    I also offer the Sterling ProReg-D external regulator. This regulator is a value regulator and does not offer any way to limit alternator output in order to pair it with your belt. While the ProReg-D is less money the Balmar regulators are a better match.

    CMI-90-ERH Specifications:This is not a cheaply built run of the mill automotive grade alternator with a dumb internal regulator. This is a direct drop in for the very common dual foot alternators found on many Yanmar's.

    Built in Maine: These alternators are hand built in the shop right here at Compass Marine Inc. the parent company of This ensures a quality product at a very, very fair price. This alternators is not just a few dollars less, it costs hundreds less than the competition. Some of the components are made overseas, some in the USA, but we sourced the best components we could possibly find, and tested them, to meet the value to performance ratio we were looking for. For example the rectifier in this alternator costs 5X what the rectifier used in an automotive grade alternator would cost.The rectifier uses six 70A diodes for a cooler running alternator.

    This alternator is specifically designed to fill the gap between a true high performance alternator (see the other alternator offerings from Balmar or CMI/Grasser) and the factory alternator. It was designed to meet a price and performance niche not available to boaters previously. This is a what we consider a medium duty alternator.

    The CMI-90-ERH comes standard with a tachometer output, called a stator tap or AC tap, for diesels that run the tachometer sense off the alternator. Not all diesel engines drive the tachometer from the alternator, but many do including some Yanmar models

    The CMI-90-ERH is set up for external regulation only. It has no internal regulator, although it may look like one. We are manufacturing our own field connection pathway for this alternator and it uses what looks like a stock internal regulator but it is not. The conversion from internal to external regulation still uses the factory located plug positions as opposed to a Mickey Mouse level pig tail of wires dangling out of the alternator frame for the field & stator.

    Special features:

    • Intended to fit & replace a Yanmar / Hitachi dual foot alternator
    • 98A cold rated & 90A hot rated with good high idle performance.
    • High amperage rectifier with six 70A diodes and more cooling surface area.
    • Machine wound stator of 14GA top quality magnet wire means better cooling and higher temperature tolerance.
    • Precision machined rotor and slip rings for greater contact at all RPM.
    • Tighter tolerance of stator/rotor gap for better performance.
    • High copper content brushes. This yields excellent conductivity and longer brush life.
    • Ready to accept an external regulator (I recommend only Balmar regulators).
    • 1/2" / 13mm single v-pulley or 3/8" / 10mm single v-pulley (please specify when ordering)
    • Billet machined pulley not cheap stamped steel.
    • Hand assembled in by Compass Marine Inc. in Maine USA
    • 3.15" Dual foot / saddle mount to fit Yanmar engines