Look around on the site. I wonder if that second brush on your alternator needs to be grounded.
Voltage issue at battery.
- Thread starter jmbass98
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Here's a good thread about full fielding. Alternator Full fielding..??
jmbass98
Well-Known Member
Yeah. I'm now being told by guys at Layson's (used to live nearby and go in there a lot) that the second field terminal on my roundback alternator is supposed to have an isolation washer. It currently does not, the screw is in direct contact with the terminal, no isolation washer in-between. Photo attached of what the unused field terminal is apparently supposed to look like.
Now we are getting somewhere.
jmbass98
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Anyone able to clarify whether or not that washer goes on the used FLD terminal or the unused one? I'm assuming the used one actually, since the unused FLD terminal should be grounded?
Probably both but I don't know for sure.
dadsbee
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Doesn't matter which.. but ONE of them needs to be grounded to work with that regulator. The one grounded... get rid of the tab so you don't put a wire on it by mistake.
jmbass98
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Damn, so it sounds like without that washer, the alternator's running at full field?
All right. Well I'll fix that real quick and see what happens.
All right. Well I'll fix that real quick and see what happens.
nutz4spd
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You sound like you're in the same boat as me. This is what mine looks like. I grounded one terminal to the case. There is an isolation washer under the screw in-between the case and brush. The terminal that is used is opposite with the washer under the screw head as you can see.
jmbass98
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Fixed the washer and the regulator, now it seems to be charging normally.
Park @900rpm, neutral @750~ rpm, and drive @700~ rpm.
In neutral, alternator reads 13.5~ volts. Battery will very slowly charge, prob .01v every 15~ sec. I imagine that means in drive, braking and with lights on, that it will drain slowly. Will test later when I have someone to help.
Belt is as tight as I could get it.
Is this normal operation?
Park @900rpm, neutral @750~ rpm, and drive @700~ rpm.
In neutral, alternator reads 13.5~ volts. Battery will very slowly charge, prob .01v every 15~ sec. I imagine that means in drive, braking and with lights on, that it will drain slowly. Will test later when I have someone to help.
Belt is as tight as I could get it.
Is this normal operation?
As good as it gets. 12.6v. is a fully charged battery. The alternator senses the need and charges accordingly. Your battery has been overcharged with your issue so 13.5 is fine. Good to hear you found the cause and it works well now.
13.5 at idle is fine
jmbass98
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Thanks guys for the help. Will post here again if I encounter any issues. Hopefully we're good now.
Loulang
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Wondering if you would be able to help me I am having charging issues also. I have a 66 charger with Holley sniper efi so my ballast has a wire connecting both and I have a electronic ignition and a electronic voltage regulator and a 2 field alternator with just a green field wire and the normal black to the stud. I’m getting no charge while running it actually drops .01 continuously.
The one or the right furthest away from the battery feed stud. If you use the other you will most likely burn up the regulator and warm up some wires pretty good.
Loulang
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I bought the big square voltage regulator with the pigtail and ended up melting wires on my new harness so I went back to the other electronic voltage regulator I have that on the one side oh and to wires plugged in and on the other side of the green field of wire goes to My alternator. Right now I only have the black wire to the stud and the green wire to the field and it is not charging
Loulang
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So my Greenfield wire hooks up to the one with the rubber O-ring which is furthest away
Dave6T4
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You should get the proper size spacer between the back of the alternator and the cylinder head. This is critical to maintain alignment and keep the through bolt tight. If you are increasing belt tension to keep the belt from squealing, you are not only pulling the alternator slightly out of alignment, but you are introducing a lot of stress on the through bolt. It will eventually break.
That's what I said. That is not a rubber o-ring either. It is a fiber insulating washer.
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