Charging Issue

Discussion in 'Ranchero Tech Help' started by DeepBarney, Dec 20, 2018.

  1. DeepBarney

    DeepBarney In Second Gear

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    With the lights on (and the engine running) the battery discharges and the motor stalls out. The voltage is around 12.95 when measured at the battery while running. I've gone through and cleaned up all the ground connections, though I noticed there wasn't a ground strap from the firewall to the block. Before I go replacing the alternator and hoping it'll be fixed is there anything else I should check?
     
  2. Clark

    Clark In Maximum Overdrive

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    If you haven't changed it, they do sell replacement digital voltage regulators at stores like NAPA.
     
  3. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Do a full-field test. There is a spot on the back of the alternator, where a tab is just inside the rear case. First, fully charge the battery, as low battery voltage can affect alternator function. Then, with your voltmeter across the battery terminals, take a small metal tool, and short the tab to the casing, to ground the field and push your alternator to continuously charge. You should read around 14.5-15.5 volts, and don't short it more than 10-20 seconds. If it does not respond, or the voltage is not above 14.5, the alternator should be pulled and tested, but it's likely bad. If it goes up, the regulator is, or the connections are, bad. As a recommendation, whether the regulator is bad or not, you can replace the mechanical one with a solid-state one (1975 is the year they all were solid-state); it's plug 'n' play, and if you need to maintain the original look, just swap the covers.
     
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  4. DeepBarney

    DeepBarney In Second Gear

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    Thanks I'll check that out. I did have my battery fully charged when I checked it last time. I'll put it on the charger again and test that.
     
  5. DeepBarney

    DeepBarney In Second Gear

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    Any chance you have or can point me in the direction of an image showing the field tab you're talking about. I tried yesterday to test my alternator after recharging the battery and I couldn't seem to locate the one you're talking about, none of the things I connected to ground seemed to do anything. Just want to eliminate personal ineptitude from the list of reasons why it didn't cause any change at the voltmeter or the engine rpm.

    I went ahead and cleaned up a few more connections: battery terminal clamps (they're a little less galled now, but really ought to be replaced because they can't be making a nice uniform connection), sprayed the plug for the voltage regulator with some brake cleaner (actually it was MAF cleaner because it's all I had on hand) and used steel wool on the voltage regulator tabs (cleaned them last time but not the socket). Battery read 13.4 before I put it on and maintained 14+ volts (fluctuated between 14.5 and 14.8 at idle) the whole time I ran the car and was trying to test the alternator and then later fixing the lights (45 minutes or so). After fixing the lights and turning on the high beams I could hear a little click at the alternator and the voltage would go to 14.63 and remain steady. I'm happy with that. Would like to test it like was suggested still though.



    For the lights I pulled the floor switch because I only had low beams working. I cleaned up the floor and back side of the switch. High beams would now come on but the lights would just randomly cut in and out for minutes at a time. So I pulled the switch apart, sprayed and scraped out all the old schmoo, cleaned the terminals with steel wool, and put it back together. That got me 4 steady functioning lights, but some looked a little weak. So I cleaned the connections at the light bulbs. Much better. They glow properly now and as good as they likely can without upgrading the harness and/or the bulbs.

    Farm trailers and old Land Rovers you've been great mentors.
     
  6. 1965 Ranchero 66G

    1965 Ranchero 66G In Maximum Overdrive Unubtanium Member

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    Most any parts store will ck your charging system for free.
     
  7. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    The tab is kind of hard to locate; I'll snap a pic from one of my books and email it to you...I just need an addy to send it to.
     
  8. andrewok1

    andrewok1 In Maximum Overdrive GOLD MEMBER SILVER MEMBER

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    Ford 1966 alt wiring
    [​IMG]
     
  9. andrewok1

    andrewok1 In Maximum Overdrive GOLD MEMBER SILVER MEMBER

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  10. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    I'm in error. The 'tab' is on GM internal-regulator alternators. So I found the on-car test procedures, and as soon as I have an email addy, I'll fire them off to you.
     
  11. DeepBarney

    DeepBarney In Second Gear

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    Ah ok. I thought I was going crazy. Email sent. Thanks all.
     
  12. DeepBarney

    DeepBarney In Second Gear

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    Yep, I've got an AutoZone close by that will and it'd be easy enough for me to do that, but then I wouldn't have learned how to do it.
     

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