Voltage Regulator
- Thread starter nodemon
- Start date
-
Not really.
The alt gauge measures Amps
The voltage regulator regulates the voltage going into the battery based on the load on the alternator.
So if you have a high load like the lights are on. The ammeter will read discharge then with the engine running the ammeter will read in the middle because the alternator is supplying just the amount of power the load needs.
If the ammeter is reading high then it is trying to power a high load between the ammeter and the battery or the battery itself.
I had a similar situation a week or so ago.
Turns out the battery was on its way out. Not saying that's your issue.
My symptoms were 10 amp charge current but the charge voltage was low like 13 volts.
The alt gauge measures Amps
The voltage regulator regulates the voltage going into the battery based on the load on the alternator.
So if you have a high load like the lights are on. The ammeter will read discharge then with the engine running the ammeter will read in the middle because the alternator is supplying just the amount of power the load needs.
If the ammeter is reading high then it is trying to power a high load between the ammeter and the battery or the battery itself.
I had a similar situation a week or so ago.
Turns out the battery was on its way out. Not saying that's your issue.
My symptoms were 10 amp charge current but the charge voltage was low like 13 volts.
Resting voltage on my battery is 12.3v.
I guess I'll keep searching out the issue.
Thanks for the response..!
So was mine. But would only charge to 13 and change but the ammeter was showing a 10 amp load with nothing but the engine running.
I put the battery on a charger till it went into trickle charge mode, took only an hour but the charging voltage was only going up to about 13 and change. The car would also only go to about 13 and change, but show 10 amps charge. 1st line right of center.
After I replaced the battery the car would go to about 14 and change but not show much on the ammeter
Both batteries had resting voltages in the 12s
Batteries have a built in resistance. As they age the resistance increases.
BU-902: How to Measure Internal Resistance.
At some point you can not put in enough current to over come the internal resistance.
This is my understanding of the basics of how it works.
Last edited:
Airstream65
Well-Known Member
Airstream65
Well-Known Member
If you decide to replace your VR, DO NOT get a parts house VR! I went through 4 that were bad out of the box, I ended up getting a black Mopar performance one and it solved my under charging issues.
67Dart273
Well-Known Member
I don't understand your answer. Of course it can. One that for some reason is causing a "full field" (full charge) condition, and or a large capacity alternator, or an alternator that is recharging a somewhat dead battery and actually working normally.
I used to have an SW 100A ammeter in the old Landcruiser, SB Mopar, and for quite awhile had one of the old "big frame" 105A units on there. Two batteries and a winch. Yeh, you could bury that 100A meter!!! I think I had no6 wire in the charging circuit, and should have been larger
But monitoring VOLTAGE is the key. If the thing is running at normal charging voltage, and if the ammeter will not center eventually, you likely have a battery problem.
Do a little reading in the service manuals. There's a chart in most of them, showing voltage vs temperature. The other "go to" really popular problem, is voltage drop in the harness/ ground which can cause over-voltage, but that will not "bury" the needle.
Did you get an to an answer to your issue?
You didn't say which way it is indicating so I'll offer you this.
The ammeter is calibrated to show approximately 40 amps to 40 amps. Anytime it shows more than 30 amps discharge or charge that is an indication that something is seriously wrong. Soon damage will start to occur in the wiring. If its over 40 amps then I would shut down immediately and if the gage is still showing 40 amps, then disconnect the cables ASAP. (discharging with the engine shut down is a bad short).
IIRC you are working on 70 or 72 Demon. It would have come with a isolated field voltage regulator and alternator. That regulator controls the field by switching the ground connection of the rotor's wiring. If the wire from the alternator field terminal to the regulator's control terminal is grounded, then the rotor's winding will be powered all the time. Voltage will then follow rpm. (RPM goes up, voltage goes up) Anything that draws current will draw more current, that includes a battery recharging. The ammeter will reflect that.
Resting voltage on your battery is a bit low. I would try charging it on a battery charger.
Voltage readings tell us energy levels between the two points being measured.
Ammeters show the amount electrons flowing through a location in circuit. An easy way to remember is to associate the word current for electricity to current for a flowing river.
Identifying Chrysler Alternators (1960-1976)
Roundback and Squareback refer to the style of housing. Roundback through model year 1969. Roundback for model years 1970-71 usually has a slightly different rear housing Squareback Revised Squareback Is most easily differentiated by the thin middle between the housings. Overall these...
www.forabodiesonly.com
A battery on low charge, even with the regulator working fine (controlling to aprroximately 14.5 Volts) can draw 35 to 40 amps.
An example using a manual charger shown here
www.forabodiesonly.com
An example using a manual charger shown here
Charging Battery with Alternator - Warning
We've discussed this here more than a few times. Usually about how easy it can be to cook the battery or overloading the charge wiring. Here's another reason. "Any attempt to charge a low battery by the alternator will result in stator windings burning out" ebay item # 222689173585 This is...
www.forabodiesonly.com
Trickle charged the battery... This is where my amp gauge is after it's been running for a minute or so... but at first start it is just below +40...
That's about right.
One can estimate a little better after observing where the needle sits with everything off.
But IMO the main utility of the built in ammeter is to observe the behaviour, so seeing approximately 5 to 10 amps charging after a minute is OK.
I have seen similar and suspect this happens when:
A battery is losing its storage capacity.
Slight delay in the voltage regulator's initial response to full fielding after start up. I *think* this is worse with high draw alternators (such as revised squarebacks).
The voltage response can be observed by connecting a voltmeter during start up.
Bonus from doing this is you can observe the voltage drop when the starter is engaged. If its down around 9.5 - 10 Volts when the starter is turning its an indicator the battery capacity is on the low side although still functional.
---
edit: Dana in post 2 is describing similar observations.
This is a situation where using a portable voltmeter in conjunction with the built in ammeter can reveal a lot more than either alone.
Last edited:
It's possible the trickle charger can't supply some minimum amps needed for a recharging.
Trickles are fine for maintaining the float charge but I don't know if they can be effective when a cell voltages are low and/or there is some sulfaction on plates and acid stratification.
Trickles are fine for maintaining the float charge but I don't know if they can be effective when a cell voltages are low and/or there is some sulfaction on plates and acid stratification.
67Dart273
Well-Known Member
The main thing is, that when the engine is warm (actually the VR which is temp vs voltage sensitive), and when the battery gets "up" and normalized, that the needle predominately runs near center. If it favors "always charging" a little bit, either the voltage is high (I've posted hundreds of times on voltage drop and grounding) or else the battery is sulfated. On cars that sit a lot with the battery "partly down" this can be an issue.
-
