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Alternator rewinding

  1. Oct 4, 2009 #1
    I am looking at rewinding an alternator and have a few questions.
    I believe that the length of the wire determines the max volts and the gauge determines the max amps. Is there a formula or some test I can do to determine the length and gauge I need the wire to be.

    I have two scenarios:
    240v 20amps
    15v 90amps

    Thanks in advance

  2. jcsd
  3. Oct 6, 2009 #2


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    No, I don't think it is reasonably possible to do this.

    There are web sites that claim it is easy, though.
    for example.
    Or this one:
    http://simplewindalternator.info/can-i-rewind-a-95-mustang-alternator-to-charge-a-144v-electric-car-main-battery/ [Broken]

    These days, rewinding alternators just to fix them has become so expensive and requires so much expertise, that it is usually cheaper to fit a new alternator. Getting one to operate on voltages it was never meant to work on would seem pretty hopeless unless you were already someone who could rewind alternators.

    Also, these devices are wound in a very complex manner and unless you can supply 12 volts to your final product, you would also have to rewind the rotor. These have windings on them that depend on the wire being very thick to hold them in position.

    One remote possibility, and I haven't tried this, is to get to the AC output before it gets to the diodes and try to transform this to a higher voltage with a transformer.
    Last edited by a moderator: May 4, 2017
  4. Oct 6, 2009 #3


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    Gold Member

    Look for a book entitled: Alternator Secrets. Not sure who the author is, I just recall the title.
  5. Oct 7, 2009 #4
    Thanks for the replies.
    I will have a look at those sites and the book. It's not a car alternator though, it's an older petrol alternator / generator.


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