Alternator not charging...??
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Joined: Mar 2017
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From: Opelika Alabama
Alternator not charging...??
Hello and happy holidays to everyone. My 78 has very recently began to read on the volt gauge that it is not charging which is evidenced by dim interior lights Etc. I have a cut off switch to my battery as many of us do. This morning I decided to test it in the old school way by cranking the car and as it is running at approximately 2,000 RPMs I turn the cutoff switch off. The car immediately died. Am I right in my theory that if the alternator were charging the battery would continue to run the engine?? Thanks in advance!
Last edited by dant849; Dec 24, 2018 at 05:10 PM.
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From: SW Florida.
Better test Shine the headlights on a wall at night and shut the motor off and see if they had lights get dimmer. Hitting the cut off while running can fry an alternator. Or make it over charge like crazy. Also, if wired wrong, it could shut off with disconnect even though charging. Odds are you are right though.
Thread Starter
Advanced
Joined: Mar 2017
Posts: 73
Likes: 1
From: Opelika Alabama
Better test Shine the headlights on a wall at night and shut the motor off and see if they had lights get dimmer. Hitting the cut off while running can fry an alternator. Or make it over charge like crazy. Also, if wired wrong, it could shut off with disconnect even though charging. Odds are you are right though.
Burning Brakes
Joined: Dec 2002
Posts: 1,179
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From: STANTON CA
Better test Shine the headlights on a wall at night and shut the motor off and see if they had lights get dimmer. Hitting the cut off while running can fry an alternator. Or make it over charge like crazy. Also, if wired wrong, it could shut off with disconnect even though charging. Odds are you are right though.
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Joined: Mar 2017
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From: Virginia
I had similar symptoms ( dim headlights, and low indicated voltage). A new 140Amp, 12si Powermaster alternator fixed it.
I wouldn't be in a rush to trust the stock gauge, though. Do you have a multimeter or digital timing light that can check the voltage when running, at the battery and also at the alt? There is a chance there could be a circuit fault (ground) or other issue, and this may help diagnose it before spending money.
But it's probably the alternator.
I wouldn't be in a rush to trust the stock gauge, though. Do you have a multimeter or digital timing light that can check the voltage when running, at the battery and also at the alt? There is a chance there could be a circuit fault (ground) or other issue, and this may help diagnose it before spending money.
But it's probably the alternator.
Last edited by Bikespace; Dec 25, 2018 at 12:00 AM.
Thread Starter
Advanced
Joined: Mar 2017
Posts: 73
Likes: 1
From: Opelika Alabama
I had similar symptoms ( dim headlights, and low indicated voltage). A new 140Amp, 12si Powermaster alternator fixed it.
I wouldn't be in a rush to trust the stock gauge, though. Do you have a multimeter or digital timing light that can check the voltage when running, at the battery and also at the alt? There is a chance there could be a circuit fault (ground) or other issue, and this may help diagnose it before spending money.
But it's probably the alternator.
I wouldn't be in a rush to trust the stock gauge, though. Do you have a multimeter or digital timing light that can check the voltage when running, at the battery and also at the alt? There is a chance there could be a circuit fault (ground) or other issue, and this may help diagnose it before spending money.
But it's probably the alternator.
Intermediate
Joined: Sep 2018
Posts: 40
Likes: 12
From: Huntingtown, MD
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,581
Hello and happy holidays to everyone. My 78 has very recently began to read on the volt gauge that it is not charging which is evidenced by dim interior lights Etc. I have a cut off switch to my battery as many of us do. This morning I decided to test it in the old school way by cranking the car and as it is running at approximately 2,000 RPMs I turn the cutoff switch off. The car immediately died. Am I right in my theory that if the alternator were charging the battery would continue to run the engine?? Thanks in advance!
Last edited by MelWff; Dec 25, 2018 at 12:20 PM.
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