[East]

I am not sure if it is a resistor but when I disassembled my alternator, this part was burned.

This part is never pictured in the rebuild kits.

Alternator not charging battery. 12.5 volts when engine is idling or revved.

[johnta1]

That's the regulator.

["QUICK-SILVER"]

Originally Posted by johnta1

That's the regulator.

He's talking about the little wire wound resistor on top of the regulator.

Not sure about them...some alternators have them and some don't.

I always suspected it was the difference between cars with lights and cars with guages. Not sure though, because I've seen them used in both applications.

IDK
Clay

[East]

Yes, that was what I was referring to in the picture.

I disassembled my new replacement alternator and it also has one of those installed.

I just purchased the 12SI from NAPA yesterday and after it was installed, I was not getting charge to battery.

That is why I was looking for rebuild kits. What happened was that I was clocking the rear case and I pulled it apart too much. When I was putting it back together, I found a piece of one of the brushes that chipped away a small chunk. I then disassembled the unit being replaced so that I could take one of the brushes.

That is when I seen that the resistor was burned in the old one. But in the new one, the person that assembled the alternator tightened the screw holding the resistor so tight, it twisted one of the ends crooked so that it does not look like the one I circled in the picture.

Did not come across a kit that was showing that part being included.

I am not sure what to do now.

[STEELCITYFIREBIRD]

Take it back to NAPA and have them get you one that is clocked correctly for your application. Tell them what happened. NAPA is one of the few decent parts stores left, they will make it right for you. It is usually best to go to the store during the day on a weekday, that is when the manager or key decision makers are there.

["QUICK-SILVER"]

Send a pm to stellar. I tried calling the shop number and he had closed for the day. If anyone can he can tell you what that gadget is.

You can get brushes to replace the one that broke. Easy to change with a paper clip or tooth pick to hold the brushes in place. You pull it out the back once the alternator is back together.

Clay

[Half-Inch Stud]

GReaaaat question. I knew the answer a few years ago, and forget right now.

I think it ia a "protect" load in the brief event that the battery is connected while the Alt isa running.

So it protects the Regulator from a brief high Voltage jump when the cable id removed from a battery.

I think.

[STEELCITYFIREBIRD]

http://forums.maxperformanceinc.com/...r.php?u=150909

[1969GiPper]

Originally Posted by "QUICK-SILVER"

Send a pm to stellar. I tried calling the shop number and he had closed for the day. If anyone can he can tell you what that gadget is.

You can get brushes to replace the one that broke. Easy to change with a paper clip or tooth pick to hold the brushes in place. You pull it out the back once the alternator is back together.

Clay

Back in the 80's I was attending meetings at Delco Remy in Anderson, IN. Between meetings we got a tour of the alternator plant. To hold the brushes in place before assembling the alternator they used the equivalent of a plastic toothpick. They had boxes of them that must have contained millions. If you dropped one they just grabbed another, easier and faster than bending over and picking it up from the floor. They gave me a handful before I left. If I looked hard enough I probably could find one in the tool box somewhere. However it would be faster to just get a wooden one from the kitchen.

[stellar]

It is a 40 ohm wire wound resistor. The alt will function with or without it. The reason for it is if the rotor winding becomes open the dash indicator light will come on. Without it and the rotor becomes open the light will not light. The alt will be a bit slower to turn on with it but you will never know the difference. If you are making a one wire alt be sure to NOT replace it as the alt will be very hard to turn on. Rotor windings seldom open. If you need it or want it I am sure I have some.

[East]

I have NOT taken it apart again and it is still installed. Voltage at the battery is 12.5 while engine is at idle or revved, just like original/old one was doing.

I had already taken the brush from the original and reassembled it before I posted.

The new alternator was no difference from the original; no charge to battery.

I will remove the new one and take it apart to check internal components.

I need to find out what else could be wrong, assuming that the new alternator was working from NAPA.

The toothpick method does work. I used a paperclip as I was taught in auto mechanics class in high school way back in the day.

Thank you all for your responses.

The original 12SI was better than the alternator that I bought from Auto Zone as it put over 14 volts to the battery at idle where the other one had to be above idle before putting out charge to battery.

I installed the better cooling fan in place of the metal fan that originally was installed on the new one. The new alternator was cast with the ridge for the better fan but I don't know why it came with the less efficient fan.

-----Kevin

[gtofreek]

What Stellar said.

With the alternator unplugged, and the key on, with the engine off, make sure all three wires have power to them with a test light. If the red wire in the plug, and the main power wire on the back do not have power, the alternator will not charge. The small wire in the plug is for the Alt light.

[East]

Yes sir, and thank you for directions.

Directions: use 12 volt test light with key on, test main large and wires in connector [1 and2] for power.

If no power to main and #2 in connector, problem is elsewhere. # 1 in connected to idiot light.

I also found a diagram pertaining to my initial question regarding resistor.

[gtofreek]

Don't convert to self exciting. That is not a good way to do it. You'll have to rev the engine up to get it to start charging everytime you start it.