Forums General Discussion alternator option

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This topic contains 5 replies, has 4 voices, and was last updated by  Miss Kathleen 4 months, 2 weeks ago.

  • Author
  • #225075

    Rock Richardson

    I have a 58W westerbek and would like to put on a new alternator was wondering what size I can go with ? would like to go as big as possible

  • #225076

    Bryan Bywalec

    Are you willing to go to dual belts? I’ve heard that 110 amps is about as large as you can go with a single belt. The engine should be fine although it robs about 2-3 horsepower to do 110 amps. If you want something larger than that you might also add a switch to deactivate the unit when you find yourself in need of a few more horsepower in adverse conditions.

    1 user thanked author for this post.
  • #225077

    Rock Richardson

    just want what will fit on the boat, not sure what is on it. but I am sure that its original equiptment

    thanks rock

    SV Topaz

  • #225078

    Rock Richardson

    will any marine alternator work as long as its under 110 amps ?

  • #225079


    Check out the Hamilton Ferris PM 125
    Works with a smart regulator and a single belt. Make sure the pulleys are in alignment.

  • #225080

    Miss Kathleen

    If the normal V belt is used a double pulley is required. You will most likely find that any alternator around 120A will have a double pulley.

    A further improvement in order to maximize the 120A/130A alternator is to remove the standard regulator and install a smart regulator. The general rule is to have an alternator rating that is 25% of the installed battery amphour rating.

    I used a Leece-Neville 120A unit with dual pulleys in addition to the standard alternator. The 120A unit is for the house batteries whilst the standard 50A unit is for the Starter battery.

    All cables work through a dual battery switch with a VSR.


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