Totally frustrated...need help on a 12 volt conversion, Delco 10si

phartman

phartman

Senior Member
Running a 12 volt Delco 10si conversion on my flathead. Tried 2 different replacement alternators, and can't get the warning light to go out when the motor is running. I run a voltage gauge and a warning light. The warning light is hooked up to terminal 1 on the top of the alternator. Power to the warning light is supplied from the adjacent Gas gauge.

Terminal 2 is jumped to the B+ wire, which is hooked to the hot side of my Ford solenoid switch. Terminal 2 is hot all the time. Engine fires like a champ, battery is new.

Terminal 1 is NOT hot when the motor is off, and gets very little current with the motor running (less than one volt).

In order to make the warning light go off when the motor is running, shouldn't terminal 1 be making 12 volts??? As I understand, that with the motor running the warning light would get 12 volts from both Terminal 1 and the battery side, no current would flow, and the light would turn off. The warning light dles go ON in the keyed position, but fails to go out when the motor is switched on and the alternator is making power.

With the motor running, I can put my voltage meter and jump from Terminal 1 and ground to the case, and I am getting a very low voltage reading- again, less than 1 volt.

Do I have the correct alternator from the parts store? It is from a 1978 Camaro with 350, as per the instructions from this article.

http://www.madelectrical.com/electricaltech/delcoremy.shtml

Very frustrating, and insight you might lend is much appreciated. Thanks in advance.
 
I don't know why you want a warning light with a volt meter.
I would guess if you got a 12 volt relay and powered to it when it failed ,wire to light when lite .Light means no power.
 
The whole point of the 10 si unit is that you can run both. The #1 terminal is specifically set up that way for an alternator warning light. I have both gauges and warning lights in all my cars. Green for electricity, red for oil.

You might overlook the gauge, but when that warning light comes on, you see it right now! Great precaution.

So why isn't mine going out, even though the alternator is making power?
 
Make sure the alternator case is grounded, I ran a #8 from the case to intake. Those horseshoe adapters are usually painted.
 

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I jumped my #2 right to the output terminal of alternator saves running wire, #1 to a filament type indicator bulb other side to 12 volt keyed supply. Should work. Zeke
 
Lawson Cox said:
I am old and have forgotten a lot in my day but I don't remember seeing any of this kind of $hit on a stock flathead. Maybe you should be on the HAMB.
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Nobody on FordBarn has done a 12-volt conversion with a Delco alternator? Forbidden? My mistake, I didn't know. Apparently, I grossly misjudged the focus of Fordbarn and the temperment of the participants here.

My, my. Yup, I am in the wrong place. Don't worry, it won't happen again. Sorry for disturbing anybody.
 
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Is this a rebuilt alternator ? It was common for the indicator light to glow if the diode trio had uneven resistance or one of the diode's was shorted in the diode bridge here is a link to test the diode trio and bridge http://constructionforklifts.tpub.com/TM-10-3930-644-14-P/TM-10-3930-644-14-P0257.htm If you set your voltmeter to AC you may be able to detect some AC voltage not being rectified by the diode's prior to removing the alternator. My guess is the diode trio is bad.

Regards,

Brian
 
That funny your putting a flathead in a Camaro.
If you have a 4 post regulator.
The one that says I or ign
If you wire to turn on engine ign that wire would go to IGN on regular.
You have to put blub in line with regular.
When key is on it lights
when you get voltage output light goes out.
Get a book and look it up.
 
phartman said:
Nobody on FordBarn has done a 12-volt conversion with a Delco alternator? Forbidden? My mistake, I didn't know. Apparently, I grossly misjudged the focus of Fordbarn and the temperment of the participants here.

My, my. Yup, I am in the wrong place. Don't worry, it won't happen again. Sorry for disturbing anybody.
Click to expand...

I can only speak for myself: I Welcome You. Yours is a really neat truck. Nicely done. Wish i had one like it. Looking forward to hearing more from you. Best of luck. ...jack
 
Hi there, Seems you have everything wired up correctly. Terminal #1 should have an output equal at least to battery voltage eg 12 volts or more so that it cancels out the warning light when alternator is charging at typical 14 volts. I suspect there is at least one faulty diode inside your alternator, even though it might be charging OK. Maybe an auto electrical shop can test run it in their test bench and do the appropriate repairs for you. Probably the diode pack would have to be replaced. The warning light bulb should be only about 2 watts maximum rating. Just a note on #2 wire which should be run around to the battery side of starter solenoid or some other power source so that it reads the system circuit voltage. Jumping it onto the alternator battery terminal defeats the purpose of having it. By detecting the slightly lower voltage in the cars battery operating system (sensing circuit) adjusts the alternators output to cope with system demands such as ,lights on, heater fan on and other loads. Good luck, regards, Kevin.
 
I hooked mine jut like Ross's diagram shows.

My light comes on for a bit, I have to keep the RPM's up a tad over idle...when I mentioned this, I was told it's possible that I don't have enough resistance in my light bulb, and should add a resistor.

Does the light go out when the RPMs are increased?
 
phartman said:
Nobody on FordBarn has done a 12-volt conversion with a Delco alternator? Forbidden? My mistake, I didn't know. Apparently, I grossly misjudged the focus of Fordbarn and the temperment of the participants here.

My, my. Yup, I am in the wrong place. Don't worry, it won't happen again. Sorry for disturbing anybody.
Click to expand...

Plenty of Fordbarners have converted their cars from 6V to 12V. No need to get upset over one persons comment. I am sure many here will give you some good advice.
 
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