Unique Products for Your Boat
  • CMI-90-ER - 90A Motorola/Prestolite/Leece-Neville Externally Regulated Alternator

    $431.50 $364.50


    We Do Not Ship Alternators Internationally 

    IMPORTANT: If you are unsure about fitment, or compatibility with LiFePO4 batteries, please use the "Contact Us" tab at the top of this page.

    The CMI-90-ER

    NOTE: Yes the 90A alternator actually costs more than the 105A alternator because the stators & rotors costs us more. This is due to lower volume purchases for the 90A stator / rotors (we just don't sell as many).

    This is the only Leece-Neville / Motorola case alternator we know of that is available & already set up for external regulation. What sets this alternator apart from an off the shelf unit are the components chosen to upgrade, tweak it and make it ready for installation. High copper content brushes, high output diodes, fit-kit & a custom billet machined pulley set this unit apart.

    The CMI-90-ER includes a custom billet machined 3/8" belt pulley (not cheap stamped steel), an upgraded high copper content brush assembly, external regulation conversion, heavy duty rectifier, and a custom 1" to 2" spacer/bushing kit so it will fit either 1" or 2" mounts and accept either a 3/8" or 10mm pivot bolt.

    None of these items come standard with any "off the shelf" 8MR you'll find. These features are all added by Compass Marine Inc. so you have a ready to run unit. Even if you were to source the parts and build this alternator yourself you simply can't beat this price.

    External Regulator: 
    We can package this alternator with either a Balmar MC-614H or ARS-5H regulator. We strongly recommend setting the Belt Manager feature to level three or four when setting up the regulator. It's also mandatory that an alternator temp sensor be used.

    CMI-90-ER Specifications:

    This is not a cheaply built re-badged automotive alternator with a dumb internal regulator. This is a marine alternator spark protected with a single 1" or 2" foot. The 1" to 2" spacer is included and is $26.00 in additional components alone.. This 90A externally regulated alternator is intended to replace the stock alternators found on many Westerbeke or Universal diesel engines or Caterpillar or Cummins engines. It will fit any engine that uses an 8MR style alternator.

    This alternator fills the gap between a true high performance alternator (see our other alternator offerings) and the factory alternator. It was designed to meet a price and performance niche not available to boaters previously.


    The CMI-90-ER comes standard with tachometer output studs (stator tap) for diesels that run the tachometer sense off the alternator. Not all engines drive the tachometer from the alternator, but most Westerbeke and Universal engines do. The CMI-90-ER is set up for external regulation only. It has no internal regulator. You will need an external regulator to install this alternator.

    Special features:

  • Intended to fit many Universal & Westerbeke diesels that use an 8MR Leece-Neville
  • 90A cold rated, with good high idle performance.
  • 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.
  • High performance diode rack.
  • Unidirectional Fan
  • Billet Machined Steel Pulley - 2.6" Diameter X 3/8" or 10mm Belt (I have these custom machined 1/2" on request)
  • Brushes are high copper content not run of the mill carbon brushes. This yields superior conductivity and considerably longer brush life.
  • Ready to accept an external regulator (I recommend only Balmar regulators).
  • Isolated ground for steel or aluminum boats or for using a shunt in the negative path..
  • Hand assembled/built by Compass Marine, from raw components, in Maine, USA

    *All CMI Alternators are custom built and may require a 1- 2 week lead time.