"excite" my one-wire alternator? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71k5 · 01-10-2003, 10:14 PM

My '71 Blazer with 350 and one wire alternator has been sitting for a couple of months; when I started it the ammeter didn't move so I revved it a bit which usually got it to start charging, but not this time. Isn't there a way to ground one of the connections on the alternator to "excite" it and get it charging again? I didn't put a voltmeter on the pos and neg terminals to see if it was REALLY charging. Also, I think there's a way to hook up an idiot light which will excite the alternator too...Can anyone help with this one?

MellowYellow70 · 01-10-2003, 10:21 PM

I run a 220Amp single wire in my vette. You should always have some sort of output when the motor is running. The alternator usuaully isn't fully excited until around 2000 rpm's or so. For instance, the one in my vette only puts out about 10vdc when started up, however when rev'd to 2000rpm's I get a rock solid 13.8vdc all day long while running.

First thing first, you should check and see if there is any output, do you have a fusable link in series?

Longhorn Man · 01-11-2003, 02:22 AM

That 10 volts you are getting in the vette when you first crank it is not a charge, but actual battery voltage.
71K5, you said you revved it a bit, did you try revving it more than you have in the past? As in, if you used to blip the throttle to 1200 RPM, you tried 1500?
Have you done anything to it since you drove it last? Like a pully replacement or electrical work?

71k5 · 01-11-2003, 12:43 PM

Thanks, guys... now that it's over 25 degrees outside and sunny, I'll start it and put a volt meter on it and run it up to about three grand and let you know how it goes. It's been sitting for a while, so maybe a rodent of some kind munched on some wires. I'll check it out....

Gordo · 01-11-2003, 01:03 PM

If you have access to the back side of the alt you will find a small D shaped hole near the rear bearing cap. If you insert a metal object, such as a nail, into the hole and bottom it out, then allow the nail to ground against the side of the D shaped hole, while the engine is running, you will bypass the internal regulator forcing the alt to put out max power. This is done briefly only to test the total output of your alt, if it's healthy you will see the voltage on your voltmeter climb to 17 plus volts. The Delcotron alt needs at least 4.5 volts to exite it. Engine idle speed should be enough to trigger the alt unless like longhornmail said about changing pulleys. Possible the brushes are worn down and or greasy/dirty and not making good contact inside the alt.

71k5 · 01-12-2003, 09:56 PM

Thanks, Gordo...I'll give that a try. The other stuff I tried didn't work but I didn't get into it too deep; only ran it long enough to pull my '85 2wd out of the mud to hard surface to I could change it's fuel pump...why does everything break at once??? Ha Ha!

red71cheyenne · 01-13-2003, 05:44 PM

Mine does the exact same thing after sitting for a while. If you take a jumper wire and run it from the one wire lead on the back of the alternator to one of the two that are on top of the alternator, for just a second, it will start putting out again. The stator loses its charge after a while. You will have to try it once to see which terminal it is under the rubber plug. The plug is the one on top of the alternator. There are two terminals under it for connecting to a two wire system. Don't ground these. You want to apply power to one of them for a second and then you will hear the alternator start making voltage. If this isn't clear, email me and I'll try to explain it better. Jeff.

71k5 · 01-13-2003, 09:10 PM

Jeff - - I think I heard of that procedure before but wasn't sure exactly how to do it, but one last question; should I do the junper wire thing with the engine running?

chevyman 68 C/10 · 01-13-2003, 09:34 PM

Your wife or girl friend doing a slow strip tease is almost always sure to exite anything. Ha ha

Ed ke6bnl · 01-14-2003, 08:44 AM

Quote:

Originally posted by red71cheyenne
Mine does the exact same thing after sitting for a while. If you take a jumper wire and run it from the one wire lead on the back of the alternator to one of the two that are on top of the alternator, for just a second, it will start putting out again. The stator loses its charge after a while. You will have to try it once to see which terminal it is under the rubber plug. The plug is the one on top of the alternator. There are two terminals under it for connecting to a two wire system. Don't ground these. You want to apply power to one of them for a second and then you will hear the alternator start making voltage. If this isn't clear, email me and I'll try to explain it better. Jeff.

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Ed ke6bnl · 01-14-2003, 08:48 AM

Quote:

Originally posted by red71cheyenne
Mine does the exact same thing after sitting for a while. If you take a jumper wire and run it from the one wire lead on the back of the alternator to one of the two that are on top of the alternator, for just a second, it will start putting out again. The stator loses its charge after a while. You will have to try it once to see which terminal it is under the rubber plug. The plug is the one on top of the alternator. There are two terminals under it for connecting to a two wire system. Don't ground these. You want to apply power to one of them for a second and then you will hear the alternator start making voltage. If this isn't clear, email me and I'll try to explain it better. Jeff.

I can't recall which of the small spade leads to connect to but the the literature for my one wire conversion kit made a point of the fact that you will do no damge to touch both briefly. I may be nescessary on a new one wire install. Mine fired up the first try. Good luck Ed ke6bnl

71k5 · 01-14-2003, 10:28 PM

Thanks, Ed. I'm anxious to try the jumper or the wire in the hole to get the alternator running again, but it will probably be Saturday before I can get to it again, but I will let everyone know the outcome!
Dick

01-10-2003, 10:14 PM	#1
71k5 Registered User Join Date: Feb 2002 Location: Manchester, PA Posts: 138	"excite" my one-wire alternator? My '71 Blazer with 350 and one wire alternator has been sitting for a couple of months; when I started it the ammeter didn't move so I revved it a bit which usually got it to start charging, but not this time. Isn't there a way to ground one of the connections on the alternator to "excite" it and get it charging again? I didn't put a voltmeter on the pos and neg terminals to see if it was REALLY charging. Also, I think there's a way to hook up an idiot light which will excite the alternator too...Can anyone help with this one?

01-10-2003, 10:21 PM	#2
MellowYellow70 Registered User Join Date: Sep 2000 Location: Gower, MO. Posts: 219	123 I run a 220Amp single wire in my vette. You should always have some sort of output when the motor is running. The alternator usuaully isn't fully excited until around 2000 rpm's or so. For instance, the one in my vette only puts out about 10vdc when started up, however when rev'd to 2000rpm's I get a rock solid 13.8vdc all day long while running. First thing first, you should check and see if there is any output, do you have a fusable link in series? __________________ If patience is truely a virtue, Then I am so screwed 1970 Chevy SWB 331 sbc and all the goodies. Under resurection 2001 Vette

01-11-2003, 01:03 PM	#5
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	If you have access to the back side of the alt you will find a small D shaped hole near the rear bearing cap. If you insert a metal object, such as a nail, into the hole and bottom it out, then allow the nail to ground against the side of the D shaped hole, while the engine is running, you will bypass the internal regulator forcing the alt to put out max power. This is done briefly only to test the total output of your alt, if it's healthy you will see the voltage on your voltmeter climb to 17 plus volts. The Delcotron alt needs at least 4.5 volts to exite it. Engine idle speed should be enough to trigger the alt unless like longhornmail said about changing pulleys. Possible the brushes are worn down and or greasy/dirty and not making good contact inside the alt. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

01-13-2003, 05:44 PM	#7
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	Mine does the exact same thing after sitting for a while. If you take a jumper wire and run it from the one wire lead on the back of the alternator to one of the two that are on top of the alternator, for just a second, it will start putting out again. The stator loses its charge after a while. You will have to try it once to see which terminal it is under the rubber plug. The plug is the one on top of the alternator. There are two terminals under it for connecting to a two wire system. Don't ground these. You want to apply power to one of them for a second and then you will hear the alternator start making voltage. If this isn't clear, email me and I'll try to explain it better. Jeff. __________________ 1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty

01-13-2003, 09:34 PM	#9
chevyman 68 C/10 Registered User Join Date: Feb 2002 Location: Gilmer, Texas USA Posts: 313	Your wife or girl friend doing a slow strip tease is almost always sure to exite anything. Ha ha __________________ 69 Chevy short fleet side soon to have LT1 and 4L60E pb. ps cruise and air. 68 Chevy short fleet side 400 sb 5 inch chop top pb. ps. pw. 350 auto and shaved handles 68 anniversary no engine long wheel base 400 auto FOR SALE 68 Chevy fleet side long wheel base complete parts truck.

01-11-2003, 02:22 AM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	That 10 volts you are getting in the vette when you first crank it is not a charge, but actual battery voltage. 71K5, you said you revved it a bit, did you try revving it more than you have in the past? As in, if you used to blip the throttle to 1200 RPM, you tried 1500? Have you done anything to it since you drove it last? Like a pully replacement or electrical work?

01-11-2003, 12:43 PM	#4
71k5 Registered User Join Date: Feb 2002 Location: Manchester, PA Posts: 138	Thanks, guys... now that it's over 25 degrees outside and sunny, I'll start it and put a volt meter on it and run it up to about three grand and let you know how it goes. It's been sitting for a while, so maybe a rodent of some kind munched on some wires. I'll check it out....

01-12-2003, 09:56 PM	#6
71k5 Registered User Join Date: Feb 2002 Location: Manchester, PA Posts: 138	Thanks, Gordo...I'll give that a try. The other stuff I tried didn't work but I didn't get into it too deep; only ran it long enough to pull my '85 2wd out of the mud to hard surface to I could change it's fuel pump...why does everything break at once??? Ha Ha!

01-13-2003, 09:10 PM	#8
71k5 Registered User Join Date: Feb 2002 Location: Manchester, PA Posts: 138	Jeff - - I think I heard of that procedure before but wasn't sure exactly how to do it, but one last question; should I do the junper wire thing with the engine running?

01-14-2003, 10:28 PM	#12
71k5 Registered User Join Date: Feb 2002 Location: Manchester, PA Posts: 138	Thanks, Ed. I'm anxious to try the jumper or the wire in the hole to get the alternator running again, but it will probably be Saturday before I can get to it again, but I will let everyone know the outcome! Dick



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