Alternator no Good?

[Doogie]

I have pretty much an original 1981 Alternator. My 2011 Battery finally gave up the Ghost this morning, so I grabbed a new one.

But, upon replacing the Battery, I noticed the AMP Gauge
won't go above about 11 Volts until I really rev it a few times, say up to 3500 RPM. Once I do that, all is well, and the VOLT Meter stays above 12V's

So, time for a new Alternator? Seems like Revving it to a high RPM gets the Alternator current flowing..

Thoughts?

Doogie

[sdg3205]

What does your multi meter say? Across the battery at rest and over 1500 rpm? When did you last clean your grounds?

[Elvis]

Check the battery bulb.


and - it's a VOLT gauge !

Amp gauge is something different. Your starter draws several hundred Amps when starting ...

[Kevin 02530]

What Elvis said, if your battery light on the dash is not coming on with your ignition in the on position your alternator won’t charge until you rev it way up. Mine did this exact same thing. Pull the binnacle and replace the bulb, it need to be a 161 not a 194 like the rest of them. This will almost certainly solve your problem.


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[DMC5180]

In addition to what was said above, verify that the wires at the alternator are in sound condition.

I have a buddy who had a similar issue with his alternator, he found that the large terminal on the main alternator wire had fatigued to the point where about 3/4 of the wire stands broken going into the terminal crimp.


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[ritztoys]

Doogie, I had that exact problem last fall. Upon closer inspection of my alternator I found the 'potting material' had basically melted away from the regulator board and this potting settled further inside the alternator. See my post......http://dmctalk.org/showthread.php?15702-Alternator-Bad
A new battery, alternator, and a alternator 'sense wire' were added, now my Voltage gauge reads in the 13v range.

[dmcnc]

IF your troubleshooting leads to the alternator, I would inspect it and test it at any local autoshop. Replacing things like the brushes or voltage regulator can be done under $20 and I've not come across a more reliable unit* than the original motorola/valeo 9AR series alternator (especially at idle). You do have a lower VIN #, which suggests your alternator might by a Ducilier: a unit I wouldn't recommend rebuilding as it was underpowered anyways.


*I've tried the Saturn (failed after a few months), DMCH (parasitic drain), and CEVAM (bad voltage regulator) alternators and none have worked as well as a quality rebuilt Motorola. My car is a daily driver so I've come across more of these issues than usual. Or perhaps it's bad luck.

[Doogie]

Check the battery bulb.


and - it's a VOLT gauge !

Amp gauge is something different. Your starter draws several hundred Amps when starting ...

Hi Elvis, sorry about that, yea I knew that. I have a 1922 Ford Model T, and the ONLY guage on the dash is an AMP guage, so I routinely mix them up :-)