Amp gauge fluctuates at any RPM
- Thread starter Road/Rage
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Loose drive belt for the alternator?
Ill check btut im sure its tight!
With the blinkers is super normal.
Without that type of load could be several things.
Did it do it before the VR change?
Without that type of load could be several things.
Did it do it before the VR change?
Any of these look familiar?
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I had to "just guess" I'd say it's a nasty alternator signal. As long as it's charging and there's no smoke or flames, I'd call it ok.
Could be a LOT of things. Get it running and charging at night and open the hook and look. If you see a bunch of tiny sparks inside the alternator, the stator windings have worked loose, rubbed each other, and rubbed through the insulation. Could be a loose connection in the infamous ammeter circuit, ANYWHERE. ANY terminal ANY wire connection from the alternator output, through the bulkhead, the ammeter, back out through the bulkhead, the fuse link, any other connection on the road to the batter
COULD BE THE "welded splice" broke. That was the VERY FIRST ONE I FOUND on a buddy's 68RR in the Navy in San Diego. I knew nothing about them, but I had the shop manual for my 69. We tore the dash/ cluster apart in his apt parking lot and I found it and soldered the splice back together. He thought I was nuts for awhile, and then after we found it, I was the hero. I was not too damn sure myself. This was somewhere around 71--73, NAS Miramar, San Diego.
I am 76. I was a Navy electronics tech, ETR-2. I fixed GCA RADAR and TACAN
Could be a loose connection/ bad VR/ bad brushes, but these are normally a slower cycle time
START by taking nothing smaller than a no. 10 wire, or maybe 3x no. 12's in parallel, make up terminals and wire from the alternator output stud to a good battery POS conection, right at the battery if possible. If that stops the problem, it is in the mentioned ammeter circuit
COULD BE THE "welded splice" broke. That was the VERY FIRST ONE I FOUND on a buddy's 68RR in the Navy in San Diego. I knew nothing about them, but I had the shop manual for my 69. We tore the dash/ cluster apart in his apt parking lot and I found it and soldered the splice back together. He thought I was nuts for awhile, and then after we found it, I was the hero. I was not too damn sure myself. This was somewhere around 71--73, NAS Miramar, San Diego.
I am 76. I was a Navy electronics tech, ETR-2. I fixed GCA RADAR and TACAN
Could be a loose connection/ bad VR/ bad brushes, but these are normally a slower cycle time
START by taking nothing smaller than a no. 10 wire, or maybe 3x no. 12's in parallel, make up terminals and wire from the alternator output stud to a good battery POS conection, right at the battery if possible. If that stops the problem, it is in the mentioned ammeter circuit
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Follow the blue wire in the harness. probably broke wear they are soldered together near the master cylinder.
slantsixdan
=..=
Ammeter fluctuation can often be smoothed out by making sure all three parts of the system are at the same ground plane. Run a wire (16ga is fine) from the alternator housing (some of them have a round hole labelled "GRD" on the back housing—use a short self-tapping screw so it's not long enough to reach in and hit the rotor—if no such hole, just attach the wire under the head of one of the alternator's three through-bolts) to one of the regulator's mount bolts, and from there to the battery negative terminal.
This isn't necessarily going to solve the whole problem; might not even solve any of it—but it can't hurt and very well might help. There are multiple causes for this what you're seeing.
"New voltage regulator" doesn't necessarily mean "good voltage regulator"; it's much harder to get good parts and much easier to get junk these days. What did you buy? Also keep in mind the godawful un-quality of "remanufactured" alternators.
This isn't necessarily going to solve the whole problem; might not even solve any of it—but it can't hurt and very well might help. There are multiple causes for this what you're seeing.
"New voltage regulator" doesn't necessarily mean "good voltage regulator"; it's much harder to get good parts and much easier to get junk these days. What did you buy? Also keep in mind the godawful un-quality of "remanufactured" alternators.
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Dave999
Well-Known Member
mine did that for years
then the alternator stopped working... opening it up indicated that the brushes were worn down to tiny stumps, meaning the springs under the brushes that had been compressed since 1971 were struggling to keep the brushes on the slip rings. there just wasn't enough brush left
my alternator was original and if it was the factory fit one from this car, its done over 120,000 miles
which is about the life of an alternator brush....
mine is a prestolite-ISH alternator made under licence by the unfortunatly named EMAIL pty ltd, not a standard mopar birdcage style
you do get some on off jiggle when the battery is just on the cusp of being fully charged and general car consumption and engine rpm is low depending on type of alternator
but it doesn't last long and switching on the headlamps or the wipers usually stops it, the extra electrical consumption seen at the battery triggering the regulator to put alternator into a "Get charging" mode
on mine it didn't stop it, because the intermittent charging causing the ammeter to flap, was not caused by monitoring and control via the regulator it was just mechanical ware of the brushes
numerous causes for the problem, this is just the one that impacted me most recently but of course could have been the problem from the day in 2004 when it stopped being a daily driver to now given the few 1000 miles a year i do.
Dave
then the alternator stopped working... opening it up indicated that the brushes were worn down to tiny stumps, meaning the springs under the brushes that had been compressed since 1971 were struggling to keep the brushes on the slip rings. there just wasn't enough brush left
my alternator was original and if it was the factory fit one from this car, its done over 120,000 miles
which is about the life of an alternator brush....
mine is a prestolite-ISH alternator made under licence by the unfortunatly named EMAIL pty ltd, not a standard mopar birdcage style
you do get some on off jiggle when the battery is just on the cusp of being fully charged and general car consumption and engine rpm is low depending on type of alternator
but it doesn't last long and switching on the headlamps or the wipers usually stops it, the extra electrical consumption seen at the battery triggering the regulator to put alternator into a "Get charging" mode
on mine it didn't stop it, because the intermittent charging causing the ammeter to flap, was not caused by monitoring and control via the regulator it was just mechanical ware of the brushes
numerous causes for the problem, this is just the one that impacted me most recently but of course could have been the problem from the day in 2004 when it stopped being a daily driver to now given the few 1000 miles a year i do.
Dave
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Mattax
Just the facts, ma'am
We need to know what is it doing?
The gage shows approximately 40 amps Discharge from the battery to 40 amps Charging the battery. Center is zero.
And it will help to know what type of system it is, grounded field or isolated field.
Fairly common at slow idle, especially with a foot on the brake pedal (brake lights on).
It may be worse with new and replacement alternators as many have rotors that draw over 5 amps (aka field current draw).
New is not always good. Why was the VR changed.
The resistor is not directly in the field circuit. However one post sometimes serves as a junction where the field circuit branches off. That varies with the model year.
Shouldn't be relevant; except as noted above, if this is an add on, it can create an additional load or resistance in the shared portions of the circuit.
first video!
Round back Square back?
We don't know what car you are working on here. What alternator and what style of regulator you replaced. If it didn't do it until you replaced the regulator, I would be suspect of that new regulator. Many (most) new electrical parts are junk right out of the box. We need more information.
Dave999
Well-Known Member
round back
you can identify a standard pre 71?? mopar alternator by its round case back
Its known in some places as a P type alternator because the basic 2 wire 1 ground regulator takes 12 volt switched from the loom and applies a proportion of that to the single field connecter on the alternator. the other end of the field in the alternator is connected to the alternator case, which is ground. The regulator is on the positive side of the field coil
(+) switched 12 volt --->regulator--->field connector---->ground inside alternator case (-)
work with the black hump shaped regulator with F and Ign connectors, and a ground connection through its mounting
Square back:- later mopar alternator has a square back to the case used until 198? maybe early 90s
Known by some as an N type alternator
not sure if this N type P type naming thing is a US or a Euro slag term to differentiate easily between types
1 end of the field coil to 12 volts the other end of the field coil via the second field connector goes to the regulator
if the regulator puts out 12 volts the voltage across the filed is zero (12 at both ends) and the alternator does not charge the battery, if it puts out less than 12 volts there is a difference in potential between the 2 field terminals hence there is a current in the field, if it puts out zero volts it acts as ground and the field gets maximum voltage across it and a bigger current in the field.
(+) 12 volt----->field connector 1-------> field connector 2------>regulator----->ground (-)
in 1 case regulator near the + side and in the other case the regulator is on the - side
N type regulator sits in the negative portion of the field circuit between the alternator and ground i.e closer to battery negative
N type alternator always has two field connectors that are totally insulated from the alternator casing.
P Type may have two field connectors But usually has only one.
A second field connector if it exists is just bolted to the case with no fibre or plastic washer under it, hence is grounded in a visible external position rather than inside the case.
an internal regulated alternator (neither of the above) could be either, all the electronics for the regulator is inside or bolted to the back of the case in a plastic module.
you can spot a p type alternator with a continuity tester, should beep if you connect it between field connector and case
N type will only beep if you connect it to both field terminals, it should not beep with 1 end of your continuity tester on the case and the other on a field terminal
Dave
you can identify a standard pre 71?? mopar alternator by its round case back
Its known in some places as a P type alternator because the basic 2 wire 1 ground regulator takes 12 volt switched from the loom and applies a proportion of that to the single field connecter on the alternator. the other end of the field in the alternator is connected to the alternator case, which is ground. The regulator is on the positive side of the field coil
(+) switched 12 volt --->regulator--->field connector---->ground inside alternator case (-)
work with the black hump shaped regulator with F and Ign connectors, and a ground connection through its mounting
Square back:- later mopar alternator has a square back to the case used until 198? maybe early 90s
Known by some as an N type alternator
not sure if this N type P type naming thing is a US or a Euro slag term to differentiate easily between types
1 end of the field coil to 12 volts the other end of the field coil via the second field connector goes to the regulator
if the regulator puts out 12 volts the voltage across the filed is zero (12 at both ends) and the alternator does not charge the battery, if it puts out less than 12 volts there is a difference in potential between the 2 field terminals hence there is a current in the field, if it puts out zero volts it acts as ground and the field gets maximum voltage across it and a bigger current in the field.
(+) 12 volt----->field connector 1-------> field connector 2------>regulator----->ground (-)
in 1 case regulator near the + side and in the other case the regulator is on the - side
N type regulator sits in the negative portion of the field circuit between the alternator and ground i.e closer to battery negative
N type alternator always has two field connectors that are totally insulated from the alternator casing.
P Type may have two field connectors But usually has only one.
A second field connector if it exists is just bolted to the case with no fibre or plastic washer under it, hence is grounded in a visible external position rather than inside the case.
an internal regulated alternator (neither of the above) could be either, all the electronics for the regulator is inside or bolted to the back of the case in a plastic module.
you can spot a p type alternator with a continuity tester, should beep if you connect it between field connector and case
N type will only beep if you connect it to both field terminals, it should not beep with 1 end of your continuity tester on the case and the other on a field terminal
Dave
First video i started at idle and then increased the RPM, this is a Round Back Alt with an Electronic version of the electro/mechanical regulator. Notice how it was giggling at lower speeds then stabilized at higher speeds. TYPICAL of all Mopar alternators at lower RPM the input shaft to the alternator is not spinning fast enough generate enough current to run everything well. (many replacement alternators have a larger diameter pulley on them turning the input shaft even slower. In the videos comparing the square and round back, note the square has a larger dia pulley and even though the square is supposed to be a better alternator it did not preform as well as the smaller pulley on a round back
loose terms...
Round Back indicates the older style alternator with a grounded field system and uses the small square 1 wire in 1 wire out electro/mechanical VR
Square Back is the newer style alternator with a isolated field system and uses the larger VR with the triangular connector
@Mattax did a great job outlining the differences in this post
Identifying Chrysler Alternators (1960-1976)
Grounded Field Alternators
Isolated Field Alternators
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Voltage regulators switch the alternator between fully on and fully off with very little in between. However they typically switch faster than what's shown in the video. This is looking like the regulator has an unusually slow switching speed. Not ideal but not truly scary either. Switching too fast has its own problems.
As long as it's charging when it's supposed to I would call it good. Idling in gear with the brake on and a 60 year old car the amp meter will probably jump around a bit. My Swinger idling in gear with the ac on will kill the turn signals. Pop it in neutral and back they come. Idle speed with an old roundback is slow enough it doesn't put out enough to keep up.
I have never ever once heard this "N and P" type designation. I don't think you said so, so let me. What you are calling "P" type has one end of the field grounded and was used up THROUGH 1969
What you are calling "N" is "isolated field" that is both brushes are isolated from ground, and that began in 1970
This gets a bit confusing because of rebuilders. Some modify a 69/ earlier alternator to "make it" an isolated field, but worse, many rebuilts were once isolated and come with one brush grounded, either on purpose or not, which makes unknowing guys putting them on a 70/ later have problems.
The videos are NOT the OPs videos. I was using MY videos to offer up a visual on what the OP was seeing
Older electro mechanical regulators switched at a fairly low rate, you could easily see the relay actuating. I don't remember, anymore, I'm thinking around 1/2 a second or so. The inductive effects of the field keeps things "more even" that the on/off action of the old relay setup would suggest. Also, most ammeters have at least some lag in their readings
All I need is some popcorn and an ice cold Pepsi. I could watch these old training video for hours!
Lots of old wiring in our ole girls.
Go through and clean up the wires in the bulkhead connector. When I first bought my car I could hear a sizzle in a bulkhead connector!!! Yikes, I cleaned them up before a fire.
Another good project to help is putting your headlights on a relay in order to keep the load away from the bulkhead and out of the cabin. A FABO member sells them here, just search for headlight relay. Installing one in mine eliminated the low rpm swings.
Go through and clean up the wires in the bulkhead connector. When I first bought my car I could hear a sizzle in a bulkhead connector!!! Yikes, I cleaned them up before a fire.
Another good project to help is putting your headlights on a relay in order to keep the load away from the bulkhead and out of the cabin. A FABO member sells them here, just search for headlight relay. Installing one in mine eliminated the low rpm swings.
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