Unique Products for Your Boat
  • CMI-105-ER - 105A Motorola/Prestolite/ Leece-Neville Externally Regulated Alternator

    $423.50 $349.50


    We Do Not Ship Alternators Internationally

    NOTE:  All CMI Alternators are hand built and may require a up to a two-week lead time.

    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-105-ER

    NOTE: Yes the 105A alternator costs about the same as the 90A alternator because the stators, rotors and components cost us nearly the same. Some builders would rather grossly mark up a 15A increase in output but we don't!

    This alternator fits most engines that require a 1" or 2" foot alternator. It does not fit Yanmar engines.

    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-105-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 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.

    For the sake of it we ran the costs for a DIY build (6/28/18 pricing):

    Leece-Neville 105A Marine Alternator - Best Price on-line $253.00 + shipping

    5/8" ID X 3/8" Belt Billet Machined Pulley - Best Price on-line $36.99 + shipping

    1" to 2" Fit Kit - Best Price on-line $26.29 + shipping

    External Regulation Conversion Kit - Best Price on-line $66.95 + shipping (No Longer Available)

    Total = $383.23 + Shipping (from multiple vendors) + Your Labor

    Bottom line? The CMI-105-ER is a STEAL!!!!

    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-105-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 105A externally regulated alternator is intended to replace the stock alternators found on many Westerbeke / Universal diesel engines, Caterpillar or Cummins engines and will replace most any Delco 10SI or 12SI frame alternator. It will fit any engine that uses an 8MR style alternator or Delco 10SI or 12SI.

    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-105-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-105-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 diesel engines that use an 8MR Leece-Neville or Delco 10SI or 12SI Frame Alternator
    • 105A 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 rectifier diodes.
    • Unidirectional Fan
    • Billet Machined Steel Pulley - 2.6" Diameter X 3/8" or 10mm Belt (we have these custom machined for 1/2" belts too)
    • Brushes are high copper content, not run of the mill cheap carbon brushes.
    • High copper brushes yield superior conductivity and considerably longer brush life.
    • Ready to accept an external regulator (we 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 Inc., from raw components, in Maine, USA
    • WARNING: Not be used with LiFePO4 batteries unless current limited to 50% of output rating or installed with a Wakespeed WS500 set to not exceed 200F.