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Topic Review (Newest First)
12-27-2003 11:25 PM
jdcoic The amp gauge is of no consequence. It is just an inline meter to show you how many amps you are using, if it is more than you are producing (bad), or less than you are producing (good). I prefer a voltmeter.

The ballast resisitor is most likely not introducing the correct amount of resistance. I have no clue what a ballast resistor is rated at ohms/watts wise, but more than likely not what is required.

If you are having doubts about what exactly your alternator is doing, just measure the output voltage of your alternator while your car is running (either at the battery, or the output lug of your alternator). Optimally, it should be 14.4....
12-27-2003 10:01 AM
Bigg Redd jdcoic,

I have spent eh last 4 hours running down the wires in the car and they go as follows:

Big red wire on alt goes to negative side of amp gauge, positive side of amp gauge goes to battery cable on solenoid......The amp gauge is wired into the charging circuit... is this correct...? from the drawings it is not...nothing should be in between the alt. and the battery cable leading to the battery....

The resistor is the other issue and I think a ignition ballast resistor is the wrong thing to use...I'm going to look into that today at radio shack.

Other than that "I'm a happy camper"
Being a show car I think I will crank it today and change the oil...

Thanks George.
12-27-2003 09:27 AM
jdcoic That is the very same diagram that ended much confusion for me, and is currently how my car is wired up. I have an indicator light in place of the resistor. That's another story how the light actually works. I have a 130 Amp 12SI, and it gets pretty hot too....heat is a byproduct of the alternator making energy.

I'm still trying to figure out this choke relay thing on my car. Some relay that somehow controls the factory electric choke, and the idiot light/exciter circuit for the alternator all in the same circuit. The charge warning light in my car ('80 Trans Am) doubles as the "choke telltale". If anyone can explaing this riddle to me I'd be very gratefull.
12-27-2003 08:50 AM
astroracer Go here and check out this info...
I am not sure what the ignition resistor is rated at but your best bet would be to do as was suggested above and go to Radio Shack and pick up the right resistor.
12-27-2003 08:10 AM
Bigg Redd The question I confused with is I have used a ignition ballast as a resisitor in the charging system instead of a "Idiot" light.
NOTE: "The ignition system is not even connected with this ballast resistor, totally seperate"

The question I confused with is I have used a ignition ballast as a resisitor in the charging system instead of a "Idiot" light.
NOTE: "The ignition system is not even connected with this ballast resistor, totally seperate issue."
The resisitor is .8 to 1.2 ohms will that work????

Next question should I use an "Amp" gauge or a "Volt" gauge ? Where does that wire into Thanks George
12-27-2003 06:49 AM
Re: Confusion about Alternator wiring diagram

Originally posted by Bigg Redd
I have a Delco12Si 94 amp alternator and it gets real hot to the touch after ideling for a few minutes, with nothing on except the car running.
Don't worry about the heat... that's how the single wire alternators run... I asked the same question about my '95 GMC after I bought it and that's what a couple of mechanics and a dealership told me. Never had a problem with it yet and it still gets pretty warm.
12-26-2003 07:56 PM
jdcoic I'm not sure how much resistance a ballast resistor has...., but 10 Watt 10 Ohms is what it is supposed to be. Might just go to your local radio shack and tell 'em what you're looking for, they should be able to hook you up.
12-26-2003 06:49 PM
Bigg Redd jdcoic,

The resistor I used is a ballast resistor for an ignition system.Do you think it is too much resistance for the alternator???

pappy 32,

Thanks for the web site I did spend a good part of yesterday looking at that site, and it does have a ton of information to look at..

thanks George
12-26-2003 02:37 PM
jdcoic The GM 10 and 12 SI series alternators need 10 Ohm 10 Watts of resistance in the circuit (the 12V switched exciter circuit, not sure what the technical name for it is). Without this, they go to a full charge state (like 37 Volts or something). Cars with out an idiot light will have a resistor or length of resistor wire, and in cars with an idiot light, the light bulb istself is the resistor.

That is one of the tricks in converting to the CS series alternators, the amount of resistance is way different.
12-26-2003 08:26 AM
pappy 32 Bigg Redd

You might want to check out this site:

Then go to tech drop down link. Look at Chevy Main Electrical Power Systems. It has some diagrams and other information.

It helped me out with some like problems. Pretty good site with some stuff I didn't know or considered.

I learn new stuff everyday.

Hope this helps and let us know how you make out.

12-26-2003 08:02 AM
Bigg Redd
Confusion about Alternator wiring diagram

Hello everyone I'm new here, or as one would say "A Newbie"

I have read alot of threads and searched the "Knowledge Base" and could not find what I was looking for. I have a modified 1957 chevy and have owned it for 32 years. But since I did my frame off there are several loose ends I need to fix. I custom wired the car from my own experience and everything is fine except one thing, the charging circuit. I have a Delco12Si 94 amp alternator and it gets real hot to the touch after ideling for a few minutes, with nothing on except the car running. When I wired it up I put a resistor in the circuit from the ignition switch to the alternator. I have seen some diagrams with and without a resistor...which way do I go...with or without a resistor...Thanks George

The battery is in the trunk if that info is needed with a 1/0 wire running to the starter. (welders cable)

Great forum hope I can help out sometimes

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