Low alternator charge at idle

[Kern Dog]

I did get the Tuff Stuff alternator and voltage regulator in the car today, then the pesky no spark issue came back. I was able to get it started twice and it did seem to charge more at idle but I needed to let it warm up so it would idle on its own. I don’t have a choke. I shut it down to step away and when I came back, it would start.
I hope to have an update on both issues tomorrow.

 

[Demonic]

Your no spark issue - did you try a different coil?

 

[Kern Dog]

Oh yeah....This issue has been a real pisser to diagnose because it is so random.

Are you ready for a real weird one? Random NO spark from a MP electronic ignition system despite numerous parts swapped around...

 

[Kern Dog]

So far, it has been a good day with the car.
First, I may have determined the issue where the car would randomly have no spark. Now this new alternator seems to work as described.

Here I am with the headlights on along with the A/C fan, the two biggest draws to the system.

Fast idle, about the RPMs I’m turning at 65 mph in 5th gear. Voltmeter reading…

That is great and is more than before. The real test is at idle where before, it read around 9 volts.
Now this is where it was a problem, charging at idle.

The standard 1000 rpms where I set it.

Impressive. I call that a success!

 

[70ChargerRT]

So far, it has been a good day with the car.
First, I may have determined the issue where the car would randomly have no spark. Now this new alternator seems to work as described.

Here I am with the headlights on along with the A/C fan, the two biggest draws to the system.

View attachment 1752438

Fast idle, about the RPMs I’m turning at 65 mph in 5th gear. Voltmeter reading…

View attachment 1752439

That is great and is more than before. The real test is at idle where before, it read around 9 volts.
Now this is where it was a problem, charging at idle.

View attachment 1752441

The standard 1000 rpms where I set it.

View attachment 1752442

Impressive. I call that a success!

That’s great Greg!

 

[Kern Dog]

This alternator sure does charge well. I went from UNDERcharging to overcharging. I’ve tried 3 regulators and all three act the same. I’m over 15 volts at the gauge. The multimeter showed 14.9 at the trunk mounted battery and 14.4 at the starter relay. This will cook the battery in short order.
Dwayne mentioned an adjustable regulator and sent me a link for an eBay vendor that sells them.

 

[72RoadrunnerGTX]

Check for voltage drop between the battery on ignition 1 at the regulator plug while running.

 

[Nacho-RT74]

This alternator sure does charge well. I went from UNDERcharging to overcharging. I’ve tried 3 regulators and all three act the same. I’m over 15 amps at the gauge…

Volts

 

[Kern Dog]

Volts

Ooops, you are right. I often write that wrong.
Corrected.

 

[68 Sport Satellite]

when I experienced this before installing the adjustable VR, over the course of a dozen or so drives I fried my analog fuel and coolant temperature gauge in my non-rally gauge cluster.

 

[Kern Dog]

I have taken 2 short drives of maybe 3 miles each. I'm done until I replace the regulator!

 

[1 Wild R/T]

I have taken 2 short drives of maybe 3 miles each. I'm done until I replace the regulator!

Have you tried running a temporary ground wire from the voltage regulator case to the negative post of the battery? Have you tested the voltage at the blue wire going to the voltage regulator?

 

[Kern Dog]

I have done neither. The battery is in the trunk.
I tested voltage at the battery itself and at the starter relay. I should test it at the alternator too, maybe tomorrow. I bought the alternator from a FBBO member, he included the voltage regulator. It is plain on the face with no identifying marks or numbers. There are marks in the potting compound visible on the back side.

I just ordered this:

New Heavy Duty Adjustable Voltage Regulator and Harness for Chrysler/Dodge | eBay

Dwayne has one in the Satellite that I had here for the Vintage Air job last Spring. He seems to be happy with it.

 

[1 Wild R/T]

Thing is that blue wire going to the regulator is the reference voltage the the regulator needs to know when to force the alternator to charge... So if the wire has high resistance and the voltage going to the regulator is 2 volts low the alternator will charge 2 volts high....

You can also ground the regulator case to the alternator case temporarily to see if it effects charge voltage...

 

[70ChargerRT]

Thing is that blue wire going to the regulator is the reference voltage the the regulator needs to know when to force the alternator to charge... So if the wire has high resistance and the voltage going to the regulator is 2 volts low the alternator will charge 2 volts high....

You can also ground the regulator case to the alternator case temporarily to see if it effects charge voltage...

I was the member who sold it to Greg and I didn’t experience any problems overcharging. It’s Supposed to be the matching regulator from tuff stuff. I only sold the set up because it didn’t have enough idling amps for all of my accessories to keep my fans working at full cfm while everything was going like the AC, lights, etc., etc.. Hopefully Greg that adjustable regulator will fix your issue.

 

[1 Wild R/T]

I was the member who sold it to Greg and I didn’t experience any problems overcharging. It’s Supposed to be the matching regulator from tuff stuff. I only sold the set up because it didn’t have enough idling amps for all of my accessories to keep my fans working at full cfm while everything was going like the AC, lights, etc., etc.. Hopefully Greg that adjustable regulator will fix your issue.

I don't think there is any problem with either part... It's possible but not likely the regulator is the problem... But before replacing parts a little diagnostics could save time & money..

 

[Kern Dog]

The stock alternator undercharged, this one overcharges. The wiring is unchanged. The mounting position is unchanged.
As always, electrical stuff is my weakest point. What is simple to some is not as easy for me.
I just used bonehead logic here...I changed the parts and the results went way opposite of the other combination. I'm not complaining. I will mess around with it a bit more. I considered one of these regulators before and had figured that I'd use one if I ever switched to a lightweight Lithium battery.

 

[OneWheelPeel]

Let us know how the adjustable regulator works out, I'm sure its a matter of time until mine goes and I like the idea of a replacement with adjustability.
That said since I made the wiring changes mentioned a couple of pages ago things are great on the charging side for me.

 

[Kern Dog]

I added a temporary ground from the regulator to the alternator case. No difference.
I tried to measure resistance to the blue VR wire with the engine off and could not get a consistent reading. It would momentarily flicker to 14 or so, then go blank. The meter works on other stuff so either I did it wrong or something is weird. The plug for the regulator is retained by those clips on the side of the regulator itself but could the terminals in the plug be loose enough to not make adequate contact?

I’m going to practice testing the wires on the other cars here.

 

[1 Wild R/T]

I added a temporary ground from the regulator to the alternator case. No difference.
I tried to measure resistance to the blue VR wire with the engine off and could not get a consistent reading. It would momentarily flicker to 14 or so, then go blank. The meter works on other stuff so either I did it wrong or something is weird. The plug for the regulator is retained by those clips on the side of the regulator itself but could the terminals in the plug be loose enough to not make adequate contact?

I’m going to practice testing the wires on the other cars here.

You need to measure voltage, not resistance.. And it should be done with everything connected & the engine running..

The picture shows how to back probe a connector... I use sewing needles.... They are using a fancy tool that they sell... My way is the old cheap way..