Unique Products for Your Boat
  • CMI-ED200-ER - 200A Large Frame Extreme Duty Alternator -J180 Mount

    $899.00 $749.00
    Please list engine model/make, battery chemistry / Ah Capacity & Belt
    There is only 1 item left in stock.


     Click Here For International Shipment Info


    For the first time ever Compass Marine Inc. is offering a massive J180 large frame high performance externally regulated extreme duty alternator at sub $1000.00 prices. Comparable alternators, from other manufacturers, start at $1400.00 and go up from there.

    After many months of testing various large frame J180 mount alternators, & the internal components for performance and heat characteristics, Compass Marine Inc. is proud to introduce the CMI-ED200-ER. This 200A alternator is a literal behemoth, similar to the massive alternators found on big-rigs, ambulance, rescue and other applications where high output demand, to run high amperage equipment for long periods of time, is required.

    IMPORTANT: This is not a small frame alternator and fitting it to many marine engines, unless it already utilized a J-180 mount large frame alternator, will require custom work on your end. Please measure twice and purchase once so you do not incur a 20% restocking fee.

    The CMI-ED200-ER is the ideal alternator for charging large AGM, GEL or LiFePO4 battery banks while at the same time keeping costs to a reasonable level. CMI can control these costs because we build these alternators one at a time here in the CMI shop. The only thing we outsource on this alternator is the stator & rotor windings and the dummy regulator, which we have custom manufactured for us. With no other CMI alternator dealers to drive up the end user cost, our prices on externally regulated alternators simply can't be beat. 

    Pair the CMI-ED200-ER with a Wakespeed WS500 (best for LiFePo4) or a Balmar MC-614H and you're still at a fraction of the price of our competitors.

    The problem with typical commercial and industrial duty-alternators is they are all internally regulated and not well suited to charging the expensive deeply cycled banks normally found on boats. While fairly robust, they are designed to power aux equipment on these rigs, they were never intended to properly charge your batteries, in a healthy manner.  By building these as externally regulated units you now have full control of the charging process. We recommend using a Wakespeed WS500 or Balmar MC-614H with the CMI-ED200-ER.

    Compared to a typical small case alternator, with a maximum running temp in the low 200F range, the CMI-ED200-ER can be run at upwards of *240F +/-  (*for long life charging of LiFePO4 batteries we advise a temp limit of 220F). This means you can actually raise the alternator temp limit on a Balmar regulator, not decrease it when charging LiFePO4 batteries. With the WS500 regulator you can literally set the maximum alt temp at 220F and the regulator will run the alt at 220F +/- a couple degrees ,and no more.. The CMI-ED200-ER can deliver 125A at a typical idle speed (2000 alternator shaft RPM) and over 140A at a "fast idle" or about 2400 alternator shaft RPM. (see performance graph image) 

    Features & Benefits

    • Dual internal fan design provides maximum cooling even in hot engine bays
    • We use mil-spec high temp Kester solder during the build process,about $100.00 per pound.
    • Smallest & most compact frame of any large frame J180 mount extreme duty alternator
    • Amazing efficiency. At upwards of 68% efficient this means less waste heat to dissipate and a cooler running alt
    • Massive 62mm pulley end bearing
    • Hot forged rotor poles for less magnetic noise
    • Can handle 10,000 RPM continuously (12,000 RPM intermittent)
    • Drive end bearing fan keeps the bearing cooler so it lasts longer
    • External & internal bearing protectors keeps moisture out of the bearings
    • Brush holder seal and moisture protection
    • Direct mounted slip rings for less connections and better reliability
    • Massive 14mm slip rings means better contact and less brush chatter
    • 80A avalanche diodes mean longer life and better protection from load dumps
    • Massive rectifier heat sink means lower rectifier temps and longer life
    • Alternator shaft is 7/8" which is also .875" or 22mm


    *In order to keep costs down this alternator has not been spark tested for USCG compliance for use with gasoline engines.

    *Fitment is up to the purchaser. On most sailboat AUX engines fitment will require a custom made mount. The CMI-ED200-ER is a drop-in fit for many Cummins engines but please make sure you already have a dual foot J180 mount alternator on your Cummins before ordering..

    *This alternator is not priced with a pulley. We can offer a (76mm / 3" OD) dual v-pulley (not recommended if running the alternator at more than160A), 8 groove serpentine (66mm / 2.6" OD) or a 10 groove J10 type pulley (66mm / 2.6"). We strongly recommend ordering this alternator with a pulley installed by us as the rotor can move during shipping and possibly damage the alternator. Any damage caused by not having CMI install the pulley before shipping is not the responsibility of CMI.

    Questions: compassmarineservices at gmail dot com