Just to keep me happy. Would you test the square back alternator you end up using. Check resistance between each field terminal to the housing of the alternator with nothing else attached to them. Both should be an open cir.
Alternator - regulator mismatch?
- Thread starter BobW
- Start date
-
Just to keep me happy. Would you test the square back alternator you end up using. Check resistance between each field terminal to the housing of the alternator with nothing else attached to them. Both should be an open cir.
BobW
Curmudgeon At Large
I can do that, but it's gonna cost you, big time! ;)
Probably be a few days until I get to it, I'll post the results.
You have a bad voltage reading at the regulator coming from the ignition. Either the switch switch or the bulk head. I do a lot of these conversions.
The car will start and run much better once the voltage is corrected. This also drops the voltage to the ignition when the voltage is low to the engine compartment. Which also causes over charge
View attachment 1715657654
The car will start and run much better once the voltage is corrected. This also drops the voltage to the ignition when the voltage is low to the engine compartment. Which also causes over charge
View attachment 1715657654
Mattax
Just the facts, ma'am
No. That's a common misunderstanding in part because we commonly say 'charging' when talking about alternator output power.
That's not how it works.
The regulator responds to the voltage it 'sees' at its ignition terminal.
This is true for both types of regulators.
Lots more here
Did you look?
What the regulator ACTUALLY does is to maintain the alternator output voltage AT THE REGULATOR SET POINT which if working correctly is 13.8--14.2 AT THE REGULATOR sensing terminal.
It is NOT GOOD for the system, but you actually "can" disconnect the battery under light load and the system voltage should maintain that set point.
The reason it OVER charges when you have harness voltage drop, is that the voltage drop through the harness causes the VR sense line to be LOW, so the VR ramps voltage up until the sense point is correct. Since there is voltage drop IN THE HARNESS, voltage AT OTHER POINTS in the system is high.
When you have a "drop" problem, you should be able to measure the "running" voltage at the VR sense terminal to the VR flange, and if the VR is working correctly, that voltage will be correct at 14, regardless how high above the battery is running
It is NOT GOOD for the system, but you actually "can" disconnect the battery under light load and the system voltage should maintain that set point.
The reason it OVER charges when you have harness voltage drop, is that the voltage drop through the harness causes the VR sense line to be LOW, so the VR ramps voltage up until the sense point is correct. Since there is voltage drop IN THE HARNESS, voltage AT OTHER POINTS in the system is high.
When you have a "drop" problem, you should be able to measure the "running" voltage at the VR sense terminal to the VR flange, and if the VR is working correctly, that voltage will be correct at 14, regardless how high above the battery is running
The VR/ alternator is a sort of "servo loop." You feed battery power to the VR IGN terminal which in a Mopar is the "sensing" terminal. This is between the VR case and the IGN terminal
If the VR "sees" less than the setpoint, it ramps up field current which makes the magnetism in the rotor stronger, and this causes more output to be generated in the stator/ diodes. This then feeds out to the battery/ the VR IGN, and as that voltage comes up, the VR ramps back down. This all happens in a split second.
If you remove the cover from an original old style regulator you can see the contacts constantly pulling in and out. "Normally" you don't see this in the voltage of the system. That is because what is called the "inductance" of the alternator field slows down these cycles and sort of averages them out.
If the VR "sees" less than the setpoint, it ramps up field current which makes the magnetism in the rotor stronger, and this causes more output to be generated in the stator/ diodes. This then feeds out to the battery/ the VR IGN, and as that voltage comes up, the VR ramps back down. This all happens in a split second.
If you remove the cover from an original old style regulator you can see the contacts constantly pulling in and out. "Normally" you don't see this in the voltage of the system. That is because what is called the "inductance" of the alternator field slows down these cycles and sort of averages them out.
BobW
Curmudgeon At Large
Both field terminals tested open, may your happiness keep on keepin' on! ;)
Good information.
Got the wiring up graded, new charge terminal, wire was clean when cut & stripped. Ran a blue ign wire to the previously grounded field terminal. Waiting on the regulator & pigtail to arrive this afternoon.
Yes I did look, imagine my surprise to see this!
BobW
Curmudgeon At Large
The new VR & pigtail came late yesterday, I installed it today.
Fired up the slant and the first thing I noticed is the ammeter reading a steady, and steadily decreasing, rate of charge. No St. Vitus dance on the gauge needle!
Alternator was putting out 14.9V, battery read 14.6V at initial start
As the battery recharged it settled in at 14.2 volts and the ammeter needle was just slightly on the charge side. The car is disassembled for paint prep, so I couldn't add load from lights.
I got a better pic of the old regulator, I was surprised to see it is electronic! There is some discoloration along the large solder run.
Thanks to all who contributed and advised, I learned a bit more!
Pretty good trick at 7!!
Fired up the slant and the first thing I noticed is the ammeter reading a steady, and steadily decreasing, rate of charge. No St. Vitus dance on the gauge needle!
Alternator was putting out 14.9V, battery read 14.6V at initial start
As the battery recharged it settled in at 14.2 volts and the ammeter needle was just slightly on the charge side. The car is disassembled for paint prep, so I couldn't add load from lights.
I got a better pic of the old regulator, I was surprised to see it is electronic! There is some discoloration along the large solder run.
Thanks to all who contributed and advised, I learned a bit more!
Pretty good trick at 7!!
Last edited:
-
Similar threads
