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69 and older voltage regulator??

hunt2elk

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Looking for some advice on these newer electronic voltage regulators. I believe everything is working correctly, but these regulators seem to be putting out more voltage than they should.
I run a stock 37 amp 1 field alternator that has had 60 amp internals put in. I have 4 different brands of regulators, and they all do pretty much the same thing. Ballast resistor is bypassed. Wire harness' ate new M&H, I did take apart and check all the easy accessable terminals. Also swapped in a freshly rebuilt alt, and no change. Regulators are double grounded. Zero ohm and voltage drop to the mount.
I had .337 voltage drop from bat + to blue ignition wire on regulator. My ignition switch was original, so I bought a nosr usa made switch and swapped that in. Voltage drop is now .239 v.
So what is happening is that at about 1000 rpm, I have 14.4 volts. Problem is that as the rpm increases, so does the voltage. At 3000 cruising down the highway, it is steady at 14.8 volts.
Does anybody have a solution to drop this voltage down to 14.3 or so? Is there anyway to test the regulator output on the bench?
Maybe these readings are normal, but I sure would like to drop them some.

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I like the factory regulators, open them up and they are adjustable! Service mail tells the procedure. Once again the “upgrade“ really is not.

regulator needs a good ground, without ground it goes full charge. Put a star washer on the. Ousting bolts and make sure the are not loose in the sheet metal.

Don’t sand the paint off the firewall, that’s not where the ground happens.

Is the battery fully charged? It will put out more of the battery is low.

Do you have a ground strap from the back of the engine to the firewall, the factory did.

Did you clean the battery terminals and posts with a wire brush post cleaner?

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Last edited:
Damn near perfect if you're running a sealed AGM or Odyssey battery. About a volt high otherwise
 
Looking for some advice on these newer electronic voltage regulators. I believe everything is working correctly, but these regulators seem to be putting out more voltage than they should.
I run a stock 37 amp 1 field alternator that has had 60 amp internals put in. I have 4 different brands of regulators, and they all do pretty much the same thing. Ballast resistor is bypassed. Wire harness' ate new M&H, I did take apart and check all the easy accessable terminals. Also swapped in a freshly rebuilt alt, and no change. Regulators are double grounded. Zero ohm and voltage drop to the mount.
I had .337 voltage drop from bat + to blue ignition wire on regulator. My ignition switch was original, so I bought a nosr usa made switch and swapped that in. Voltage drop is now .239 v.
So what is happening is that at about 1000 rpm, I have 14.4 volts. Problem is that as the rpm increases, so does the voltage. At 3000 cruising down the highway, it is steady at 14.8 volts.
Does anybody have a solution to drop this voltage down to 14.3 or so? Is there anyway to test the regulator output on the bench?
Maybe these readings are normal, but I sure would like to drop them some.

View attachment 1477515

View attachment 1477516

View attachment 1477517
The old mechanical voltage regulator relied on the internal spring tension to adjust the voltage by varying when the relay contacts moved......higher tension = higher output voltage.
The electronic voltage regulator replacement uses an internal voltage divider network to sense the system voltage and adjust the on/off point of the square black transistor (shown in pix 2) which controls the system voltage in a current sinking circuit. There is no provision for adjustment......personality, don't worry about the small variations in voltage readings you noted......just my opinion of course.....
BOB RENTON
 
I have ground straps and star washers all over the place, I know that isn't the problem. I have electronic ignition on all the cars, this one has MSD. Have heard that the old mechanical regulators don't play well with those? I just can't believe someone can't build these regulators with a SCR that runs a bit lower output.
 
Have you considered going to a Denso type alternator with internal regulation so you can bypass the firewall mounted regulator?

I made the switch from factory 1 wire alternator to the 60a Denso and it is perfect. Rock solid 14a at idle with lights and accessories on. Used the factory 69 BB bracket and hold down but had to add 1/2" spacers to bring it out to align the pulleys. The only additional wire needed is a sense wire running straight from yhe alternator to battery.
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I have ground straps and star washers all over the place, I know that isn't the problem. I have electronic ignition on all the cars, this one has MSD. Have heard that the old mechanical regulators don't play well with those? I just can't believe someone can't build these regulators with a SCR that runs a bit lower output.
Its not an SCR application.....I mentioned a current sinking transistor circuit which does the field voltage control.....SCRs are used on AC to variable DC circuits. The voltage regulator noted uses a voltage divider network to sense the system voltage and control the transistor's on/off and the alternator's field voltage and subsequently its output voltage. Its an INTERNAL/DESIGN point for AVERAGE SYSTEM VOLTAGE OF 14.3 - 14.5 volts (its ambient temperature compensated). The only reason for the electronic voltage regulator control is to ELIMINATE the on/off switching of the points in the mechanical voltage regulator.....there are no transient supressor network.....it not a big deal.....
BOB RENTON
 
Have you considered going to a Denso type alternator with internal regulation so you can bypass the firewall mounted regulator?

I made the switch from factory 1 wire alternator to the 60a Denso and it is perfect. Rock solid 14a at idle with lights and accessories on. Used the factory 69 BB bracket and hold down but had to add 1/2" spacers to bring it out to align the pulleys. The only additional wire needed is a sense wire running straight from yhe alternator to battery.View attachment 1477637View attachment 1477638
I had not. Do you have a link on Summit or somewhere else of the model you have? That would get rid of all the potential wire terminal connections and ignition switch path as well wouldn't it?
 
I have ground straps and star washers all over the place, I know that isn't the problem. I have electronic ignition on all the cars, this one has MSD. Have heard that the old mechanical regulators don't play well with those? I just can't believe someone can't build these regulators with a SCR that runs a bit lower output.
I've had problems with those, when through 4 of them before upgrading! You may just have to use the newer style VR's, read towards the bottom of the page. Good Luck

 
Where are you getting the 14.8 volts from? Inside the car or the battery?

A half of a volt here and there is likely not going to cause a battery BBQ.
EDIT:
PROVIDED - the regulator is backing off the charge as the battery becomes fully charged.
If not there will be a problem but my back yard fix below will help.

I wold leave it alone and if you are concerned - turn on the headlights on a longer trip.
Bleed off the excess charge.
Around town I think it will be fine.
 
I
Where are you getting the 14.8 volts from? Inside the car or the battery?

A half of a volt here and there is likely not going to cause a battery BBQ.
EDIT:
PROVIDED - the regulator is backing off the charge as the battery becomes fully charged.
If not there will be a problem but my back yard fix below will help.

I wold leave it alone and if you are concerned - turn on the headlights on a longer trip.
Bleed off the excess charge.
Around town I think it will be fine.
I'm getting the 14.8 everywhere at 3000 rpm. Right at the battery and inside the cabin. I actually jerryrigged a Fluke meter in the cockpit and have been driving around with that on for the past week, just because the factory volt meter conversion isn't as precise. Just barely above idle it is 14.5. 2000 rpm 14.6. 2500 about 14.7. At 3000 it is steady at 14.8. Temperature doesn't affect it either, which I thought it should. The hotter ambient, the lower the reading should be.
 
I have a little LED voltage indicator tapped in to the radio feed wire.
When I start the engine I get 14.4 - 14.5
This will drop to 13.7 - 13.9 as the battery tops up.

With my electric fan on and the headlights my car does not charge at idle. The indicator shows about 11.5

If the battery is not 100% at storing charge the regulator will pump charge at it regardless.
 
At 14.8 - 14.5 volts range, which seems a little high. WHICH VOLTAGE REGULATOR are using?? WHOSE BRAND?? The old mechanical voltage regulator or one of the newer electronic versions of the old regulator? Can you substitute voltage regulators? It MAY BE a simple calibration issue. Yes...you are correct.....the higher the ambient temperature, the voltage regulator should reduce the system voltage slightly....to maybe 14.3 - 14.5 volts. It is possible that the sensing network in the voltage regulator is defective, allowing higher voltage. IF ITS THE OLD mechanical voltage regulator, remove the cover try adjusting the spring anchor upward very slightly....say an RCH. BE CAREFUL AS THE SPRING ANCHOR IS NOT AT GROUND POTENTIAL. ADDITIONALY, try disconnecting the green wire at the alternator.....the alternator will stop charging and voltage will come down.....this will prove the trouble lies within the regulator.......just a thought......
BOB RENTON
 
I had not. Do you have a link on Summit or somewhere else of the model you have? That would get rid of all the potential wire terminal connections and ignition switch path as well wouldn't it?
It does. I gutted the VR and kept it on the firewall. Ballast was already removed when I installed my Pertronix. I haven't ever regretted it.

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I had not. Do you have a link on Summit or somewhere else of the model you have? That would get rid of all the potential wire terminal connections and ignition switch path as well wouldn't it?
Check out Andy F’s website Ar engineering I think he has the Denso alternator’s and different mounts for them
 
I have a little LED voltage indicator tapped in to the radio feed wire.
When I start the engine I get 14.4 - 14.5
This will drop to 13.7 - 13.9 as the battery tops up.

With my electric fan on and the headlights my car does not charge at idle. The indicator shows about 11.5

If the battery is not 100% at storing charge the regulator will pump charge at it regardless.
This is the other part that bothers me. It never drops the charge down until I let off the gas and it is at idle. The battery has always shown a full charge. I even swapped another known good battery in to see if it changed anything, made no difference.
 
Yes I agree that does not sound right. Is the field grounded/alternator fault so the alternator pumps out full charge no matter what the regulator signals????
I am just guessing now.
 
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