alternator question

Electrical & Ignition

  1. megaivtes

    megaivtes Well-Known Member

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    so looks like my voltage reg. is going (15.6v at batt.) and as I verified my alt. amps (60) I thought I read somewhere that 2nd FLD terminal should be grounded.
    Is that right?
    As a side note, I purch. the solid state regulator from Ebay.
    https://www.ebay.com/itm/201249070790
    20210503_125311.jpg
     
    Last edited: May 4, 2021
  2. Jerry Hall

    Jerry Hall FBBO Gold Member FBBO Gold Member

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    What year car?
     
  3. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    if you are getting 15 volts with that regulator you already have grounded one brush on that alt. Pay attention if some of the brushes got a metalic washer down the screw grounding it and DO NOT CONECT THE WIRE ON THAT ONE OR WILL SHORT OUT THE WIRE! fortunatelly you didn't and the free prong there must be the one grounded with the metallic washer

    it seems you got a 70/71 round back alternator dual field grounding the brush with the metallic washer, modified to work as a single field.... and without a warning call about that. Ppl what makes that conversion at shops should clip off the prong to save from that huge mistake.

    there is a thread about a member who burnt its wiring by mistake thanks to that. Is not too old...
     
  4. megaivtes

    megaivtes Well-Known Member

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  5. RJRENTON

    RJRENTON FBBO Gold Member FBBO Gold Member

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    IMO....
    Suggest that you take the alternator back to the place of purchase, and TELL THEM you want an isolated field alternator (if you're up-grading to the Mopar electronic voltage regulator which requires the isolated field alternator) and NOT the universal one size fits all unit with one brush grounded and a double groove sheave. If you "modify" what you have then, in all probability, the warranty will be void. The problem is, most, but not all auto parts counter persons have no real knowledge of what you want, only what's shown on their computer. You must be specific as to your vehicle snd your intentions.
    BOB RENTON
     
  6. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    Well, the best would be get the right alternator with the propper brush setup which looks like this

    Remanufactured-Round-Back-Alternator-For-Chrysler-_1.jpg

    On that one you can see the brush on right being attached straight to the case without the plastic isolator. Your unit is just right the oposite, with the field attached on the opposite spot and the isolation system ( for both brushes ), like this

    w0kWV5zaUFMmCfSJ4fjf9So5Jl3nS-iDLfSv4Bn-O2DnIT3hXVrLyZdoaseWD9nWBPB-FQwVM1R9p9nE0xqP4wsWig.jpg

    That was used when still with roundback alts the charging system become on dual wired fields, specifically on 70 and 71.

    Some were made like this accepting both setups and assembling accordingly per needs to match the setup on car

    ACDelco-321-163-Remanufactured-Alternator-ROUND-BACK.jpg

    There is nothing wrong on get grounded one of the brushes if using a dual field alt onto a single field car. It will work just right the same, but just need to take care of what I told. Sure the best would be get the right alt thought. You can clip off the grounded brush, bent the prong or get it protected/sealed with a shrinking tube on prong. Anything that helps on to prevent somebody will connect the field wire coming from reg on your car To the grounded brush. On your car the wire coming from regulator is positive and connecting to the grounded brush will burn the harness as soon you put the key in RUN.

    If you want to "upgrade" to a later electronic regulator system in the future, you already have the alt and just will need to isolate the brush back with the propper isolation washer down the retaining screw... aside the later regulator, the pigtail for it and an extra wire to feed the second field.

    I was searching for the thread I mentioned but didn't have the patiente to search it furtherly. Will try later.

    Now about the voltage at batt... it could be anything, from a regulator working unpropperly up to a lack of ground at regulator mount. It needs to be correctly grounded via chassis. Or maybe also low voltage signal coming into the ign wire at regulator due poor conections from batt to ign switch up to regulator. If the batt is low, could also get high voltage up to get it at a decent charge rate, but usually not over 15 volts.
     
    Last edited: May 5, 2021
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  7. megaivtes

    megaivtes Well-Known Member

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    @Nacho-RT74
    The alt. can't be returned, its over two yrs old. I'll admit, I'm not there yet in my knowledge of alt's and dual vs single field, in fact i'm pretty bad there.
    So I bought the ebay elec. regulator based on some reading here and thought its a direct swap.https://www.ebay.com/itm/201249070790
    At this pt. should i shrink tube the other FLD and buy a mech. volt. regulator?
    I appreciate the help. I need a mentor in the elec. stuff.
     
  8. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    the other field prong isolation is just to prevent someday the field wire will be conected there. I'm assuming that's the one being grounded because if not you'll never get any voltage over 11.5-12 volts at the batt, so the system is somehow working. You can check visually anyway if it got a metalic washer down the screw.

    Now about get a mech regulator or get another new one like the one you have. I can't tell it. Yes, that's a direct swap but I have read mixed opinions about those upgraded regulators. Some ppl get them working nice, some others not. I guess you can try a mech one to check if something changes. There are adjustable ones FYI
     
    Last edited: May 5, 2021
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  9. megaivtes

    megaivtes Well-Known Member

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  10. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    As mentioned, it can be grounded on the way you preffer. The way on pic is valid, too, wiring it to the chassis, but replacing the isolation washer on one of the brushes for a metallic one is cleaner and the method used by some sellers.

    If you are getting 15 volts at batt, the alt is defintelly working and one of the brushes is already grounded. There is no way to get more than 12 volts at batt if the alt wouldn't be already working
     
  11. 451Mopar

    451Mopar Well-Known Member

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    With 15+ volts output the alternator is fine. Make sure the body of the voltage regulator is well grounded to the firewall, and also the firewall/regulator body has a good ground to the engine block.
    If the problem persists after making sure the grounding is good then disconnect the field wire at the voltage regulator, and the alternator should quit charging. If it continues to charge, then you might have a wiring problem where the field wire is getting voltage from an unknown source (maybe someone miswired the wiring?)
    If the charging stops with the field disconnected (it should), try a different voltage regulator. The regulator might be bad?
     
  12. megaivtes

    megaivtes Well-Known Member

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    Tried 2 VR's, no change.
    I thought it might be grounding at VR because I painted eng. compartment. I used Dremel and sanded down at attachment holes along with toothed washer. Even ran a ground frm bolt to batt w/no change. I'm going to check main ground and also ground 2nd FLD terminal today. Will post results.
     
  13. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    Have you checked voltage at blue wire of regulator without engine running just with key in RUN ? I'm thinking a low voltage reading there could make to excite the regulator for more voltage.
     
  14. 451Mopar

    451Mopar Well-Known Member

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    The voltage regulator mentioned, it just an electronic version of the oil style points regulator that regulates the positive power to the single field connector on the old style alternator.
    https://www.ebay.com/itm/201249070790

    If the alternator is outputting power with the regulator disconnected, then either the alternator has a short from the power output to the field (but that would drain the battery fairly quick), or the wire going to the alternator field is getting power from some other source, or is the wrong wire all together.
    The field wire should go directly to the regulator and nothing else.

    The field wire should be green, not blue. The blue ignition power wire goes to the input to the regulator on this system configuration.
    If your using a later alternator with the newer style voltage regulator that regulates on the ground side, then the blue wire goes to the alternator field, and the green goes to the triangle connector of the new style voltage regulator.
     
  15. RJRENTON

    RJRENTON FBBO Gold Member FBBO Gold Member

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    Excellent explanation.....and.....once again, good old Nacho RT74 has got it wrong.... perhaps he should go back and re-read the shop manual......or learn the fundamentals....
    BOB RENTON
     
  16. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    I couldn't expect less from you.


    Anyway, the field wire seems to be a replacement being spliced somewhere into the engine harness? doesn't even seem to be blue.

    if there is a blue wire feeding the alt field, harness was modified and doesn't match with the year being talked.

    I can't read anywhere the engine is running without reg connected

    there is no other information on the thread aside the regulator being used or any other wire arriving to the alt to take any other conclusion.

    So I still can't find what is wrong on my replies.

    But... whatever
     
    Last edited: May 11, 2021 at 4:06 PM
  17. RJRENTON

    RJRENTON FBBO Gold Member FBBO Gold Member

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    The word you are searching for IS.....ACCURACY.
    BOB RENTON
     
  18. megaivtes

    megaivtes Well-Known Member

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    Gentlemen...I appreciate everyone's help because I'm lost on elec.
    I ran some tests. Current wiring goes like...Alt FLD goes to Coil +, Coil - goes to ECU, ECU goes to VR?
    Very confused as to why i'm getting 15.2 at batt and 15.45 at fuse pnl. Gonna re-check grounds.
    SNIP-VOLT.jpg
     
  19. 451Mopar

    451Mopar Well-Known Member

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    Try disconnecting the field wire from both alternator and regulator. Turn on ignition power and test if either end of the wire has voltage. It should not have any.
    If it does, use electrical tape to cover the terminal ends, and run a new wire directly from regulator field terminal to alternator field terminal.

    Also, Looking at your chart, you also have excessive resistance drops in the wiring. Check bulkhead connections.
     
  20. 451Mopar

    451Mopar Well-Known Member

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    Taking the time to look at the numbers above, everything (parts wise) might actually be working correct?
    If the voltage regulator set point is to regulate at 14.45 volts, then it is doing its job. There is just a bunch of resistance / voltage drops in the wiring.
    Between the alternator output and the regulator input, there is a voltage drop of 1.4 volts! it might be the bulkhead connectors or the ignition switch.
    To test, just jumper a wire from the alternator output to the voltage regulator input. The regulator should now see the correct alternator output and regulate it down to the regulators set point.
    If that is the problem, a sort-of fix would be to use a relay to connect the regulator input like tested, activated by the ignition power (original regulator power in wire.)
    This will not fix the voltage drops between the alternator and battery, that would take another large AWG wire to connect the alternator output directly to the battery.

    The above would be considered "doing the right thing the wrong way".
     
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