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Discussion Starter · #1 ·
About a month ago I finished installing a Vintage Air system which including moving the alternator to the drivers side to make room for the compressor. When I had the alternator out I noticed the pulley had a pretty substantial wobble. After putting it back in initially it read normal at around 14.5 volts on my under-dash meter. Slowly I have noticed it deteriorating, it now sits around 13 volts and if I use the turn signal it pulses with the signal between 12.5-13 volts. Does this sound like the alternator is dying? If so any recommendations on amperage size? Can you over do it with the amps? It needs to be able to power all the standard electrical, AC, after market stereo system, and auxiliary fans.

Thanks,

Hank :vroam:
 

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Trifive Automotive Electrical Wiring Expert
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It sounds like it could be a slipping belt. Have you checked tension? When you changed sides, did you change to a different width belt? If the belt doesn't fit the pulley, it can start slipping over time, even though it seems tight enough. It can slip worse if the battery is not fully charged. A weak battery will put more load on the alternator and cause it to slip more.
Usually 70 to 100 amps is fine and you can't put too many amps, it only puts out what is needed. BUT, use a heavy enough wire for the amparage of the alternator.
 

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Discussion Starter · #4 · (Edited)
Thanks gentlemen, I will check it out. Don it definitely could be a slipping belt as I did replace it but it still seems too loose and if I floor it the belt will squeal for a brief moment.
 

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Discussion Starter · #5 · (Edited)
So I replaced the belt with a tighter one, and am still having the same problem, low voltage readings sitting mostly around 12v now but sometimes jumping up to 13. I pulled a voltage meter out and checked the cables running from the battery terminals at 2000 RPMs and it was jumping all over the place from 12-15, sound like an alternator issue still? Should it be showing a constant voltage reading?
 

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Trifive Automotive Electrical Wiring Expert
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I would check for a loose connection between the alternator and the battery. It sounds like the alternator is intermittently trying to charge the battery. Check the voltage at different places such as battery, ignition switch, horn relay, ect. and see if the voltage is stable anyplace.
Could the pulley be slipping on the alternator shaft?
 

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All of the above suggestions are good, but I have one for you. You mentioned that when you had the alternator off the pulley "wobbled." There should be nearly zero radial play in the bearing. I personally don't know tons about alternators, but if by chance the bearing is bad enough to allow the rotor to contact the stator when it's spinning I think that could short out the alternator causing your voltage fluctuation.

Now that I said all that I hope I interpreted what you meant by wobble.

What ever it is good luck!

Jim
 

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Discussion Starter · #10 ·
I haven't done anything yet Jim, haven't had time. One stupid question I have is if I want AutoZone or Oriely's to test it do I need to remove it or leave it in the car?

Thanks,

Hank
 

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Trifive Automotive Electrical Wiring Expert
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Most of them can test the alternator as well as doing a battery load test on the car.
 
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