Dual alternators

  1. CompoSimmonite Member

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    4,609
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    Werrington, Stoke-on-Trent
    If I fit a second alternator to a vehicle would they both charge the main battery ? The second, leisure, battery would have a split charger.
    Cheers
     
  2. WorkshopChris

    WorkshopChris Forum Supporter

    Messages:
    5,046
    Location:
    South East Essex
    If you are fitting a 2nd alternator, why split charge?
     
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  3. Ashley Burton

    Ashley Burton Member

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    Northamptonhire
    @CompoSimmonite I would just fit a higher amp alternator

    It doesn't really make sense why you would want to fit a second one otherwise
     
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  4. CompoSimmonite Member

    Messages:
    4,609
    Location:
    Werrington, Stoke-on-Trent
    Two 65ah alternators far cheaper than one 130 amp, built in redundancy on a 4x4, and best of all - why not :)
     
  5. tom2207 Member

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    2,501
    Location:
    uk northern ireland
    are you fitting two alternator drive belts too ??
     
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  6. 8ob

    8ob Forum Supporter

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    moscow on thames
    I was also wondering about that, its going to get very complicated.

    Bob
     
  7. Ashley Burton

    Ashley Burton Member

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    Location:
    Northamptonhire
    Just seems like alot of work if you ask me!

    Keep it simple is my normal approach
     
  8. CompoSimmonite Member

    Messages:
    4,609
    Location:
    Werrington, Stoke-on-Trent
  9. Agroshield Member

    Messages:
    1,365
    I just guessed at some terms and a search for 'parallel alternator wiring' looks to give some promising leads.

    SWAG here but seems to me that the input to the split charger won't care where its juice comes from but the issue will be stopping one alternator back-feeding the other.
     
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  10. barking mat

    barking mat Barking at Pigeons

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    4,605
    Location:
    Brittany, The Arz Valley.
    I've boats running 12 and 24 volt alternators.
    Just add another to crank pulley on the front, and build a bracket.
     
  11. Domdom Forum Supporter

    Messages:
    346
    Location:
    UK, Warwickshire
    I’ve done it to power a rather large in car sound system some years ago. Whatever you do, DO NOT connect them both to the same battery. You will get one charging at a slightly higher voltage than the other, no 2 alternators are ever the same, and the result will be some rather expensive smoke the likes of which even Lucas would be proud of.

    This goes for split charge systems as well. If you have 2 alternators then leave out the split charge. You never want the alternators connected. Think of an alternator like a wife, if you have 2 you’d better make damn sure they never see each other.

    Technically you could do it with some big blocking diodes but at those current ratings the big alternator is much cheaper. And you lose 0.7v across a diode as well.

    My best experience was with a huge alternator and some constant duty solenoids to act as a split charge relay. Electronic SC systems use diodes, transistors etc and you always get a 0.7v drop across semiconductor based things, best avoided.
     
  12. Kayos

    Kayos Member

    Messages:
    5,889
    Location:
    Yorkshire
    Fitted a second alternator to the disco just to do the rear battery. Didn't need it and split charge was fine, sold the kit for more than i paid for it
     
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