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Alternator Not Charging


awk409ak

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Hi Guys,

Yesterday I was out in my 64 Riv, and stop at a auto part store and when went to leave the battery was dead.  Store checked the battery it was good, but low on charge about 11 volts.  We removed the battery and did a quick charge that brought up to 13+ volts.  We reinstalled the battery and tested the charging system.  There was no increase of voltage to the battery, which means no out put from the alternator.  I drove it home with no issues.

Today I  started it with no issues.  Put my voltmeter on the battery with engine running 12.56 volts, loading it, it drops to 12.25, but come back to 12.55-12.57.  Shouldn't I have more like 13-14 volts?  Is it a diode or diodes that's bad?  Am I doing something wrong here?

Also, what lights should be on when the ignition switch is turned to on position?  Shouldn't I have the Amp and Oil light appear?  I know the temp light show when turned to start.

 

Art

Edited by awk409ak
clarity (see edit history)
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To troubleshoot the charging system, you need to also investigate the voltage regulator. That might be your problem.

 

The diodes on the alternator can be bench tested.

 

If you are not fluent in this, try to find an old-time automotive electrical shop to test and adjust things for you. A mechanical voltage regulator can have points cleaned with a point file and be adjusted to correct voltage. Or have a look an electronic voltage regulator.

 

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Sometimes on a car that sits a lot a little corrosion will build up in the alternator brush guides. If the commutator has a slight high spot the brush will follow the rise and stick at the high point. Just take the back of the case off and work the brushes a little.

There is a hole you can use for a pin or paper clip to hold the brushes for reassembly. Pretty easy fix and something to watch for on cars that have been idle.

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I have a show coming up Friday and Saturday.  My thoughts are to remove alternator today and test the diodes, I have located replacement diodes.  I'll check the manual on testing the regulator.  I could just take the alternator in to an auto part store and have them test the alternator too.  If my is bad then just buy another alternator and fix my mine at my leisure.  I guess I could do that with the regulator too.  The timing is poor for this to happen.  Haha, but it always is right.

 

What is meant by "hot" battery?  Is the the voltage high?  It was on a quick charge Saturday and was a tad over 13 volt to get me home.

 

Thanks,

Art

Edited by awk409ak (see edit history)
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3 hours ago, awk409ak said:

I have a show coming up Friday and Saturday.  My thoughts are to remove alternator today and test the diodes, I have located replacement diodes.  I'll check the manual on testing the regulator.  I could just take the alternator in to an auto part store and have them test the alternator too.  If my is bad then just buy another alternator and fix my mine at my leisure.  I guess I could do that with the regulator too.  The timing is poor for this to happen.  Haha, but it always is right.

 

What is meant by "hot" battery?  Is the the voltage high?  It was on a quick charge Saturday and was a tad over 13 volt to get me home.

 

Thanks,

Art

What he means is the 12.6 volts is what a good battery reads after it was charged recently and after the charger is removed.

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23 hours ago, awk409ak said:

Hi Guys,

Yesterday I was out in my 64 Riv, and stop at a auto part store and when went to leave the battery was dead.  Store checked the battery it was good, but low on charge about 11 volts.  We removed the battery and did a quick charge that brought up to 13+ volts.  We reinstalled the battery and tested the charging system.  There was no increase of voltage to the battery, which means no out put from the alternator.  I drove it home with no issues.

Today I  started it with no issues.  Put my voltmeter on the battery with engine running 12.56 volts, loading it, it drops to 12.25, but come back to 12.55-12.57.  Shouldn't I have more like 13-14 volts?  Is it a diode or diodes that's bad?  Am I doing something wrong here?

Also, what lights should be on when the ignition switch is turned to on position?  Shouldn't I have the Amp and Oil light appear?  I know the temp light show when turned to start.

 

Art

 

Art, 

 

I had the same thing happen to me on the way to the BCA Nationals in 2017. On my way to pick-up my brother-in-law I stopped for lunch. I came out and battery completely dead. I made it to his house after a jump. We spent the rest of that VERY hot summer day swapping out the voltage regulator, the alternator and the battery. To make a long story short my problem was the connections at the alternator. They had looked good with a visual inspection but, obviously were not. The old connectors were snipped off and replaced. Problem solved and have not had a problem since. I am not going to say that is your problem but, that is a simple check and fix to do before you take more drastic and time consuming measures.

 

When key is on you should have the following lights: OIL, AMP and COLD (if the engine is not warmed up).

 

Bill

Edited by Riviera63 (see edit history)
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All is good.  Had to replaced the regulator too, but don't really know if it was bad.  During replace of regulator it appear the connector can become loose.  I also had to replace the connector on the alternator, because it just fell apart during removal process.   Important thing is, it's charging now.

 

Art

Edited by awk409ak (see edit history)
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