"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?

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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?

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?

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....

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.

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!

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.

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?

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

i

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

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