Help please charging system!!!!

Discussion in '6.9L IH & 7.3L IDI Diesels' started by SDbernhardt, Jan 11, 2018.

  1. SDbernhardt

    SDbernhardt Full Access Member

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    I recently figured out that the exciter wire to my 3g alternator is working. I have found that the battery light in the guage cluster is what excites that wire. My question is I have read that you can put a resistor in line to bypass the light bulb but no one has mentioned what ohm resistor to instal. Second question will it hurt to just run a wire from the battery to excite the alternator?? I don't know what kind of voltage the exciter wire is supposed to be getting. Thanks in advanced. 3g alternator externally regulated ON the alternator not fenderwell.
     
  2. 79jasper

    79jasper Chickenhawk

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    Check the 3g conversion threads.

    Sent from my SM-G892A using Tapatalk
     
  3. OLDBULL8

    OLDBULL8 Good Morning Ya'll. Supporting Member

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    Here might be your answer. That resister around the light is 510 Ohms.

    3G Alternator.jpg
     
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  4. 79jasper

    79jasper Chickenhawk

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    Plus the resistance of the bulb?...

    Sent from my SM-G892A using Tapatalk
     
  5. pelky350

    pelky350 Full Access Member

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    In my cluster when changing my bulbs out the battery light had a resistor on the back of the bulbs housing, I think all came with one?
     
  6. jwalterus

    jwalterus Made in America

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    Wired parallel, it's an either/or current path.......
     
  7. Macrobb

    Macrobb Full Access Member

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    Why not just use a small bulb with leads? Not only do you get a resistor, but you get a visual indication of it working.

    I've used a turn signal or marker light plug from the JY before on a 1G swap onto a tractor; worked great.

    You do *not* want to run it directly - the alternator and regulator will both get hot, with the key on engine off, and it'll drain your battery more than usual with the key on engine off.
     
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  8. madpogue

    madpogue Full Access Member

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    Um, NO. Current goes through BOTH paths. Current is the SUM of the current draw of the two resistances. Resistance is, well, the inverse.
     
  9. SDbernhardt

    SDbernhardt Full Access Member

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    I appreciate all the input here
     
  10. jwalterus

    jwalterus Made in America

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    Yes, but I didn't realize we were going for super specific here. We aren't trying to tell him how to wire speakers to keep from frying an amp. LOL
    Bulb should be around 50 ohms on a 3 watt bulb.
    Combined resistance roughly 45 ohms when the bulb is lit.
    Bulb burned out, resistance is 510 ohms, which would be bypassing the bulb, the same as the OP was asking.
    I was trying to explain it without having to think or type this much.
    That says optional instrument cluster.
    Therefore I would think that anything 510 ohms or less would work.






    To the OP: Ignore the rest of this post, just run the damn 510 ohm resistor if it's what you want to do. LOL
     
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  11. SDbernhardt

    SDbernhardt Full Access Member

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    Hahaha will do... gonna try to change the bulb out and if that doesn't work then resistor it is... I have to have this up n running to go to work Monday so trying to have all my ducks in a row to work on it when I get done work today. Thanks again
     
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  12. franklin2

    franklin2 Full Access Member

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    No need trying to get into ohms law and all that stuff. Pretend the bulb burnt out. The resistance you need is around 510 ohms. That is what the resistor is for, to keep the alternator charging in case the bulb burns out. If you change the bulb when it burns out, you do not need the resistor.
     
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  13. 79jasper

    79jasper Chickenhawk

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    See, I thought if the bulb was out, it wouldn't charge.
    I seem to recall a few people having to replace the bulb. Maybe the resistor was burned out?

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  14. jwalterus

    jwalterus Made in America

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    Could be.
    I don't run a 3g. Nor do I have a standard voltage regulator.
    And nothing on my truck could be considered "factory wiring", down to a re-pinned ignition switch......
     
  15. SDbernhardt

    SDbernhardt Full Access Member

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    From what I gave read on other forums and places is that they all run the exciter wire though that bulb but some gauge clusters came from the factory with a resistor installed so if the bulb burnt out it wouldn't effect charging, but some did not come with the resistor installed so if the bulb went out so did your alternator. I can't remember the year split of when they did vs didn't have it but not sure of when it was.
     

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