High amp alternator.

Discussion in 'Fuel System & Electrics' started by Jeff maddalena, Jan 10, 2017.

  1. Jeff maddalena

    Jeff maddalena New Member

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    Edens landing
    Hi all. I'm looking for a high amp alternator for our 73 PV does any one know any manufacturer doing these or any one around Brisbane that does upgrades.
     
  2. Barry

    Barry Well-Known Member

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    Type 1 or 4 motor?
     
  3. Jeff maddalena

    Jeff maddalena New Member

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    Location:
    Edens landing
    type 2 1800 cc
     
  4. Grantus

    Grantus Well-Known Member

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    Keeping in mind VW's quirky labelling system, you have a Type 2 vehicle, but it will have a Type 1 or Type 4 motor....o_O
     
  5. Mordred

    Mordred Super Moderator Staff Member

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    Type IV (4) are either 1700 1800 or 2l. All others smaller are Type 1. You jave a type IV. You can get a 70 amp alternator that was fitted in the US from what I have seen, but they are rare. You may be able to get one rewound with a greater capacity but it has to fit in the same space and have the cooling attachments as the exisiting one does. There is a larger alternator made for Type 1 engines but this doesn't have to fit in the small space like the later motors.

    Adrian
     
  6. syncro

    syncro Well-Known Member

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    On the T3 (or Type 25) you could fit 2 alternators for 180A. I don't know if this was an option on the T2 (with a type 4 motor).
     
  7. 1500king

    1500king Well-Known Member

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    Have your standard 55A alternator rebuilt into a 75A.
     
  8. saabman

    saabman Well-Known Member

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    Just on rebuilding an alternator for a higher capacity Andrew - i gather that is a matter of removeing the windings and replacing with a thicker wire.

    The thicker wire would mean that less turns can be made fit resulting in a lower maximum output voltage. I'm guessing there is enough overhead to allow the regulator to compensate ?
     
  9. syncro

    syncro Well-Known Member

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    The difference between capacity alternators used to be changing the stator windings from star to delta.
     
  10. saabman

    saabman Well-Known Member

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    Something else to wrap my brain around
     
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  11. syncro

    syncro Well-Known Member

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    How do you think I feel. I learned all of this 45 years ago! No wonder I can't remember anything as there's no room left!:(
     
  12. rstucke

    rstucke Active Member

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    341
    Location:
    Wamberal NSW AUS
    You can put 2 diodes on the centre tap of a star wound stator and connect them to pos and neg. this gives a 15% increase. the stator ring size and winding thickness govern output current.
     
  13. Luckyphil

    Luckyphil Well-Known Member

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    So where do you fit the 2nd alternator :)
     
  14. syncro

    syncro Well-Known Member

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    Probably where the ac compressor is mounted.
     
  15. syncro

    syncro Well-Known Member

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    Are you sure that's not for a 15% increase in voltage?
     
  16. rstucke

    rstucke Active Member

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    Location:
    Wamberal NSW AUS
    Hi Phill
    No, definitely amperage. the regulator takes care of voltage by governing the strength of the magnetic field in the rotor as sensed in the charge lead (output terminal). Some alternators are designed to use the star point, they can be identified by the use of 8 power diodes (4+ and 4-) instead of the usual 6 not counting exciter diodes of which there are 3 of in each type of unit. apparently there is waste energy at the star point every time the phase shifts (it's a 3 phase device) the extra diodes allow that energy to be diverted to the dc output. The increase in output from the star point is proportional to alternator speed, not much at low speeds and about 15% on top of max output at 4500 alternator rpm. I modified a few alternators years ago (when I was in the Tafe system) by running a heavy wire from the star point out to a heat sink at the back of the alternator. The sink was connected to the output terminal but insulated from the rest of the alternator by plastic gromets. A positive and negative diode was pressed into the heat sink and there terminals soldered to the heavy wire.
    Back in those days it was impossible to find more than a 55amp alternator which drove the above mode. There's not much room behind the alternator on a type4 engine so it would need to be mounted else where (and insulated). Having said all that 70amp alternators are available for type4 engines which probably makes the above a waste of time.
    Cheers
     
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  17. syncro

    syncro Well-Known Member

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    I'd really like to know the theory behind that as I don't really understand how that would work. I know that you can increase the voltage with extra diodes in the D+/DF circuit. I think most of the alternators that I worked on went from 35A to 55A or similar.

    I think that a second alternator would be the easiest and cheapest for extra high output. If you can mount an ac compressor then you can mount an alternator.
     
  18. rstucke

    rstucke Active Member

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    Wamberal NSW AUS
  19. 1500king

    1500king Well-Known Member

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    Location:
    Adelaide, SA

    There is a 75A bosch stator that fits a bus alternator. No need to rewind anything. However, you'd rebuild the rest of it while you are at it.
     
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  20. syncro

    syncro Well-Known Member

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    It's doing my head in thinking about this as it was about 45 years ago when I learned all of this.
     

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