Alternator question

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ram250098

ram250098

69 Barracuda
Joined
Nov 25, 2007
Messages
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Location
Cookstown Ontario Canada
My voltage gauge shows I am charging at around 10.5 to 11 volts. When I rev the engine to about 2000 it pops up to 13+ volts. Should I assume it is the voltage Regulator? It is a newer solid state reg. With the car a idle I am getting 11.75 volts at the battery. Cleaned all the battery posts and field terminals and made sure the reg is grounded to the body. Still have the amp gauge hooked up as well.
AL
 
You should be closer to 1 4.0 volts at the output of the alternator, check the voltage there. You probably have a weak alternator and your regulator may be just fine.
 
Would agree with Cuda jim, I just put a Denso alt and a New Voltmeter In, It shows 14ish volts when ideling. D
 
So I guess because I am getting some juice the fields are ok, The voltage at the back of the Alt is 11.5..so time for a rebuild? The damn thing looks new LOL
Thanks guy's.
AL
 
Here is the upshot, Alt is good. But need some info. With the ignition on I tested the plug at the voltage reg and both wires are hot! Is this right.
I also thought that on the back of the Alt even though they are listed as fields one was a ground because one of the field was insulated.
Also with the ignition on I put a test light to ground and both the field wires were live. If one is a ground which on is it the Blue or the green.
Thanks
AL
 
On a 72 Dart the original alternator had a single field terminal coming out and the other end was internally grounded. If the alternator was replaced with a dual field terminal type of alternator then you need to ground one of the field terminals. If you don't it will never work.
 
Thanks so much I was wondering about that. I do have two wires that run to the voltage reg from the alt though. The Alternator rebuilder told me the one is for field and one is for ground, so I guess I will try and ground one and leave the other going to the voltage reg? What should I do with the other wire/ This will mean only one wire from the alt will be going to the voltage reg.
Thanks Cuda
AL
 
Maybe this will help. 70 Duster, 2 fields. Car sat for 20 years, fired it up; not charging,(it was when put on stands in 1987). clean grounds, alt not putting out. Buy a reman from Advanced, no go. Take it to local alt shop.
Now this gets good. He tests it, and says 1 field is internally grounded; easy fix. Then asked where I had the blue and green wires (he said it will work with wires switched). I told him that I never had a good diagram of wiring until several years ago, off computer, engine swaps, etc, it had always worked.
He asked, where was the blue wire? I said wrong terminal. He says that is great, that it was wired wrong, as if it was correct, with blue going ground, it would have fried your dash wiring.
There is a diagram in here, somewhere. Or on BBD. I don't know what 72 wiring is, or same regulator as 70.
 
I hooked a wire to what he said was the ground and with the ignition on I touched it to the alt case and got a spark...this can't be right?
Looks like someone has tied the brown wire from the ignition into the MSD box as well as the blue wire to the voltage reg. I am thinking cut the brown wire to the reg. The brown from the ignition could be supplying power to the reg constanlty
AL
 
Here is where I stand need to know what else to check.
Alt is good, voltage reg is good. I hooked up a 10ga wire from the + post on the alt and ran it right to the battery. Started car and no change. I pulled the - field wire off and tried it and got close to 12 volts but did not increase with idle speed, did the same with the + field wire..same result took off both and still same result.
Took the blue + field wire and jumped it to the voltage reg and still no change.
I am stumped.
AL
 
You may have an upgraded alternator and regulator and it may not be wired correctly for what you have. It sounds like you have a mismatch somewhere so you need to first determine what system is in there and wire it properly.
 
................1970 up uses 2 field alt................take both field wires off........turn key on engine off.........test to see which wire has 12 volts..........goes to the field farthest from the battery power cable..........post closest is the ground........back track ur work................kim..........try a higher cca battery..............
 
My volt meter is not working now ggggggrrrr anyway I took both field wires off and put a test light to check each one. With key off I have power at the positive stud and nothing at either field wire terminals. With key on I still have power at the positive stud and nothing at each field terminal.
AL
The guy who checked it was getting all kinds of juice out of it....I am stumped LOL
When they check them do they check the field terminals?
 
Hi Ted, Someone said try grounding the - field wire, I really did not want to do this but I just touched for a second to the alt case and got a small spark so I did not continue...didn't seem right LOL
AL
 
I have the Ron Francis Wiring system..
It comes with the electronic voltage regulator Standard # vr-166
There are four terminals I A S F

I think the following wiring should work on your vehicle if you have this style of voltage regulator.

F goes to one of the 2 field terminals on your alternator
s is from a keyed on 12 volt line\ignition powered
A goes to your power block, or the same stud as the large red wire coming from your alternator is at the starter, or a power distribution center

I is not used.

Make SURE you ground the voltage regulator

The second field terminal at the alternator must be properly grounded. I would do that when the car is not running.

I did some reading at MAd electrical on "remote voltage sensing"

This wiring set up has made my charging system work very well
 
Thanks for the reply Ken, I am sure it is something I over looked or one wire going where it shouldn't. When I find it I am sure I will be kicking myself in the butt for not finding it sooner LOL
AL
 
Got the car on the road today all legal like LOL
So now I have a better explaination of the charging problem.
When I get the car going around 2500rpm it charges at 13.5 volts but when the car is at idle which is 1000rpm it drops to 10.5. The only load is the electric fuel pump which is switched so with that turned off it stays around 10.5.
I have a march pulley system on the car could that be the problem, maybe it is to large of an Alt pully.
AL

SWINGER 003.jpg
 
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