This alternator won't charge.

Discussion in 'Sparky's corner' started by BrianinStLouis, Nov 9, 2020.

  1. BrianinStLouis

    BrianinStLouis Silver Level contributor

    Evening all.
    My 72 Suncoupe had been converted to an internally regulated alternator by the late great John Kemper.
    Suddenly charging problems cropped up. I found the wire from the back of the alternator to the top plug had broken off. I remove the alt, cleaned some things up, painted some brackets and fixed the wire.
    Went for a test drive. My meter said my alternator wasn't charging, so I high tailed it home.
    The car stalled in the street but I was able to coast into my driveway. I had to jump the battery before it would crank. It would only start with starting fluid.
    It seems I ran out of gas, even though my gauge said I had 1/4 tank. That's a first.
    So, off comes the alternator to have it tested. I found out it was shot. I got a new alternator, it tests good.
    I installed it, still not charging the battery. A meter across the battery while on high idle only shows about 12.5 volts.
    I removed the alt, sanded the new rattlecan paint off of the mounting brackets, then reinstalled. No improvement.
    I have the exciter wire going from the alt post to the "2" terminal of the alt plug-in on top. I actually tried it on both sides. No charging is happening here.
    My idiot light never did work. The plug from the old voltage regulator has not been cut off, and nothing is jumpered on the old plug either.
    A test light shows voltage from the alt post to the wire plugged into the "2" terminal, while using the alternator bolt as a ground.
    What the hell am I missing here?
  2. Max Damage

    Max Damage Well-Known Member

    The old wire that ran to the regulator NEEDS to be jumpered somewhere. Do that and try again. You can always just join the appropriate wires together...

    There is another thread currently (pun) going on that is this same topic search for I hate electrical issues...
    Darron72Skylark likes this.

    BRUCE ROE Well-Known Member

    The wiring for an internally regulated alt is extremely simple. Unplug 1-2 and test
    the wires. The wire to 2 should have 12V at all times, either wired directly to the
    main output stud, or to the main 12V distribution point. 1 comes from the GEN light,
    should read 12v when the ignition is turned on. Grounding it then should light GEN.

    If there are remnants of the mechanical volt reg wiring or an adapter, I would ditch
    all that to avoid increasing possible wiring faults. Bruce Roe
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    The basic wiring for the internally regulated alternator is VERY SIMPLE. At the old external regulator, find the brown wire. Cut it and extend it to the alternator with another piece of wire. The top plug of the alternator has a white and red wire. The white wire gets connected to the wire you extended. The red wire goes to the charging post on the alternator along with your original charging wire. That's it. This article has you use the original plug blue wire to extend the brown to the alternator, but it accomplishes the same thing. That is you exciter wire.
  5. BrianinStLouis

    BrianinStLouis Silver Level contributor

    Thanks for the replies guys.
    I'll dig into it again soon. I tested positive for the virus today. No pun intended.
    I'll be in the basement for awhile.
  6. racenu

    racenu Well-Known Member

    Wow tough luck, ran out of gas, no charge, COVID positive. FYI, Don’t use starting fluid on your car and a quick way to see if alternator is charging, with engine running, disconnect your battery cable, if engine keeps running your alternator is charging if engine dies... no charge
  7. BrianinStLouis

    BrianinStLouis Silver Level contributor

    Thankfully, it's not my DD.
  8. BrianinStLouis

    BrianinStLouis Silver Level contributor

    Thanks Gents.
    I followed the link posted by the Wizard, it matches with what Bruce Roe suggested. Now my charge indicator works in the dash, and my battery voltage measures over 14v with the engine running. I wonder how it was charging for the past few years? It's a mystery to me.
    Anyway Thanks again!

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