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Compass Marine How To | all galleries >> Welcome To >> Sorry We are out of Business >> Purchase a Compass Marine Custom Built Alternator > CMI Alternator Specifications
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CMI Alternator Specifications

This is not a lightly built re-badged automotive alternator with poor low end performance. I have these hand built in the USA to my own stringent specifications to ensure a quality product.

They come standard with a tach output (stator tap) for diesels that run the tach sense off the alternator. The CMI alternator is set up for external regulation and also has an internal regulator for emergency redundancy.

Special features:

-Available in 1" Foot, 2" Foot and 3.15" Yanmar/Hitachi saddle mounts.

-Hand wound stator wound from 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.

-Tight tolerance stator/rotor gap for better performance. A feature not found in standard alternators.

-Precision milled stator utilizing a special dacron/mylar insulator. The industry norm is paper.

-Rotor is precision balanced to .015 ounce inches. Industry norm is .050 - .090. This means SMOOTH operation and less harmonics.

-50A press fit diodes. Industry standard is Chinese button diodes and 25-30A rated. These diodes carry a performance rating to 300F.

-Internal wire leads are ultra high temperature acrylic coated fiberglass insulation sleeves or high temp 200C silicone wire not cheap rubber or PVC sleeving.

-Brushes are high copper content composite not run of the mill carbon brushes. This yields superior conductivity and considerably longer brush life.

-The positive stud is a beefy 5/16" not some wimpy 1/4" or #10 stud. These studs are bolted directly to the rectifier bridge for the best possible connection. Industry standard is a compression fit.

-Manufactured to match the offsets of my competitors (eg; a Balmar 6 series) so it can be converted to a serpentine kit in the future.

-All stainless draw bolts, pivot bolts and adjustment bolts a feature not found on any of my competitors products.

-Built for external regulation with an additional standard internal regulator as emergency back up.

-Please specify a 3/8" or 1/2" pulley unless going with a serpentine kit.

-Can be built with a case isolated ground for steel or aluminum boats.

-Hand built in the USA (Note: some internal components are non US made but carefully chosen)

-Built to marine standards for ignition protection.

-Universal adjustment ear for wider fit tolerance.

-Machined, drilled & tapped alternator temp sensor mount point

other sizes: small medium large original auto
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Matt Thomson 06-Nov-2017 01:07
Do you have performance curves for your CMI Alternators. I am interested in seeing what engine RPM I would need to get rated amperage output. I have a 1/2 V belt on my Westerbeke 4-107. I'm upgrading my house bank to either 3 or 4 Group 31 AGM batteries, (between 375 and 500 amps). I don't have the room to upgrade the pulley system, but if I have to reconfigure my engine compartment in the future, I don't want to have to spend another $800 - $1000 for a higher capacity alternator, so as you sugested, I plan on buying a higher capacity alternator (140 amp or 160 amp)and using a Balmar external regulator and limiting the output amperage to 100 amps to prevent belt slippage.