Alternator charging

[Pronto]

Wonder why they would want to lower voltage rather than just maintain it. Seems like they almost wanted things to go boom.

 

[No disintegrations]

For years I have seen my voltage drop at high RPM from 13.9 to 12.2 when over 6000 RPM using Autozone and other reman alternators.

Info from a local electrical rebuild shop said that our alts have a built-in provision which lessens voltage at higher RPM's.

I then examined my current alt, and found it had a pulley which is smaller than stock?

Having some stock alt cores, I installed the larger stock pulley which resulted in less alt RPM, and more stable voltage.

why would they do that or want less voltage? I think the answer is something else other than "they have circuity for that"

 

[michael evans]

I then examined my current alt, and found it had a pulley which is smaller than stock?

More voltage with a smaller pulley ? Is that what we are after ?

What I see is 13.5 volts for about a minute then it goes to 12.7 volts.

Next time I start the engine, I will time it.

 

[michael evans]

Would you look at it ?

I put the smaller pulley on the alternator and it picked right up.

Not only is it showing 14 volts, it seems to be running smoother.

 

[Pronto]

If it's working better then keep it. How about at higher rpms?

 

[mikestertwo]

Wonder why they would want to lower voltage rather than just maintain it. Seems like they almost wanted things to go boom.

The voltage is lowered to keep from over charging the battery, extending it's life. They lower the voltage to what's called the "float voltage" for the battery which is 2.25 to 2.30 volts per cell that totals 13.5 to 13.8 volts.

 

[RUQWKNF]

Would you look at it ?

I put the smaller pulley on the alternator and it picked right up.

Not only is it showing 14 volts, it seems to be running smoother.

Excellent news.
Now, keep an eye on your belt as this new pulley arrangement can affect it's wear pattern, as well as the tensioner's position. Glad you got it back to normal.

-Patrick-

 

[michael evans]

If it's working better then keep it. How about at higher rpms?

Due to the weather, I have not driven it yet. It has rained at least once the last five days.

 

[michael evans]

Long story short it makes a difference.

Was showing 12.7 volts, now at 14.0 volts (need to make a log).

It feels stronger will take it to the track soon if not it maybe at Bowling Green at the Nationals.

 

[turbo nasty]

For years I have seen my voltage drop at high RPM from 13.9 to 12.2 when over 6000 RPM using Autozone and other reman alternators.

Info from a local electrical rebuild shop said that our alts have a built-in provision which lessens voltage at higher RPM's.

I then examined my current alt, and found it had a pulley which is smaller than stock?

Having some stock alt cores, I installed the larger stock pulley which resulted in less alt RPM, and more stable voltage.

Same here...while not a AZ it was a aftermarket 170 amp alternator and the guy put a smaller pulley on it and I was losing volts at WOT above 5200 and the pulley was spinning the alt like 15000 rpm or something like that and it didnt like that. I replaced it with a stock size pulley and all was well.

 

[michael evans]

Same here...while not a AZ it was a aftermarket 170 amp alternator and the guy put a smaller pulley on it and I was losing volts at WOT above 5200 and the pulley was spinning the alt like 15000 rpm or something like that and it didnt like that. I replaced it with a stock size pulley and all was well.

Glad you brought that up.

Since my car came with the underdrive crank pulley and all others are MIA .

What are: The ideal RPMs for the alternator ?, The factory diameters for the crank and alternator ?