The Stovebolt Site Forums The Shop Area The Electrical Bay Adjusting a 12v regulator

I have a 12v regulator and a generator on my truck. The gauge always reads a discharge when running or not. The battery is hot and i know the gen. is showing a charge on my meter. I was thinking about raising the voltage and see if that would fix the problem. I'm just drawing straws. Can anybody help. Thanks as always, Steven I used the search but could not find anything on this problem.

When is the battery hot and what meter is showing a charge?

A battery should never be hot and the ammeter should show some charging after starting and eventually show a very small charge deflection.

I guess I must explain better. By the battery being Hot I meant It was fully charged with my charger. I used my hand held dc volt meter and I use it to make sure the battery is charged and to check the output on the gen. Does that help? Let me know if there is anything else I need to tell you. By the way the volt meter in the truck always showes a discharge, about a needles width. Even reving the engine won't move it. Thanks for the reply. I'm at the shop trying to read my books and maybe find something I need to do. Again, Thank you. Steven

With the engine running at a fast idle (1500 RPM or so) the voltage at the battery terminals should be 14 volts or a little more against a fully-charged battery. If you decide to adjust the regulator, be aware that the voltage setting will drop slightly when the cover is replaced due to better magnetic conduction. The unit to adjust is behind the "F" terminal and voltage is increased by raising the spring tension on the points. Some regulators have an adjusting screw, while others have a spring anchor that is bent up or down to change the voltage setting.

Be sure the cutout relay points close when the engine starts. This unit is behind the "B" wire and it disconnects the battery from the generator when generator voltage drops below battery voltage to prevent the battery from discharging itself through the generator windings when the engine stops. It sounds like the cutout relay is not closing in your situation, causing a slow discharge of the battery with the engine running.

I wrote a tech tip on DC charging systems some time ago. It's about 6 volt systems, but the 12 volt DC generator works the same way, just with different voltage settings. Good luck!

http://www.stovebolt.com/techtips/6v_charge_system/index.htm

Jerry

Here are some steps to take when checking out the charging system.

1. Check battery water and general battery condition to
see if it will take and hold a charge....Load testing
may be necessary.
2. Check wiring for damage and make sure all
connections at generator, regulator and battery are
tight and free of corrosion.
3. Make sure fan belt is tight enough to drive
generator at full capacity.
4. Run engine at medium speed. Using a wire, touch one
end to regulator base and other end to a good ground.
If this corrects trouble, regulator is not properly
grounded anymore.
5. If test 4 does not correct trouble, make this test.
Connect a wire from regulator terminal marked "ARM" or
"GEN" to regulator terminal marked "BAT" with engine
running at medium speed. If charging rate increases,
replace old regulator.
6. If test 5 does not correct trouble, make this test.
Connect a wire from "FLD" Terminal of regulator to a
good ground with engine running at medium speed. If
Charging rate increases, replace old regulator.

If none of the above test show a bad regulator then
there is probably a problem in the generator itself.

Let us know what you find.
Ken

Oh how I was hoping for a good reply and low and behold I got 2! Many thanks to all of you. I am going out to try again (3 days) to find the trouble. I now have some thing to check thanks to both of you. I'l be sure and let you know what I find. I'm thinking something simple that I have overlooked. That's usually the way it goes with me. I've got to get through with this truck so I can start on my 1951 3/4 ton chevy. It will be my 1st from the ground up restoration. Again thank you so much. Steven

Hello Fellows, Well, I'll give you an update. I bought a new battery, followed all the steps that both of you gave me and I think I may have narrowed it down to two choices.The Generator (Output 11.52 volts) or the (gauge may be not working.) Here is the following: Generator voltage, running at medium speed, 11.52 volts--Voltage at battery, also running at medium speed, 12.06. Voltage at regulator (battery term.) 11.66 volts. Armatuer voltage at regulator 11.56 volts. On test #6 I noticed that the engine pulled down but no change in gauge reading,a needle width or so discharging. I will take the generator off today and see if the brushes need replacing and also do the test that the shop manual gives. Keep talking to me- I listen and thanks for everything. You guys are always right on time. Steven

With the battery having 2.1 volt per cell on open circuit then it should be about 12.6 volt. Anything less from generator will result in discharge. More than 12.6 is charging. To drive off sulfate you need approx 14 to 14.5 volt.

What is current on generator at 11.56 volt? If it is producing current (turn on headlights for a load) and holds 11.56 then gen is more than likely OK. Adjust or replace regulator.

Dan Bentler

Before you tinker with the generator, ground the Field terminal and see if the voltage at the Armature terminal increases. If the generator is capable of producing voltage, grounding the field should put it into maximum output, as much as 20 volts or more if you rev the speed up. Don't overdo it! Are the cutout relay points closing? (Gotta pull the cover off the regulator to find out- - - -you did that, right?) Try cleaning the regulator points with a piece of business card or file card stock- - - -NEVER use sandpaper or a file! A slight bit of oxidation on the points will interrupt the field control circuit and drop the voltage output to virtually nothing.
Jerry

OK Boys, I'm going out to try these. Again, Thank you so much, Steven

I'll update you good people later. Steven

OK, this one is for"leitmotif." Under no load the Gen. was showing 11.26 volts. I turned the lights on and it went to 10.90v. You would think the gen. was not putting out enough voltage. Read the following.

This is for "Hot Rod Lincoln." I grounded the Field term. and the voltage at the gen. increased to 15.90volts, that's at a half fast idle. The voltage at the ARM. was 16.30v The cutout relay is closing. I cleaned the regulator points with a business card. The battery voltage now is 11.77 with the truck running. All the while the gauge never goes to the charge side. I can get a gen. and a voltage regulator. I'm just trying not to spend money needlessly. You know what I mean. I'm not rich! Thanks to ya'll again. If you have a suggestion please feel free to let me know. I'm at a loss as to which one is bad. Thanks so much, Steven

OK, good diagnosis so far! Watch the ammeter when the field is grounded to see if it deflects toward the charge side. It should be going virtually full-scale to the + direction with the field grounded and the engine at fast idle. You need to increase the spring tension on both the current regulator points (middle coil behind the A terminal), and the voltage regulator, (the coil behind the "F" terminal on the regulator. Don't overdo it on either one, just slightly increase the tension on both sets of spring-closed points. The current regulator prevents the generator from overloading itself when charging against a very low battery, and it shouldn't allow more than 35 amps of current flow. Some of the early generators were rated at 25 amps. The voltage regulator must be able to raise the charge voltage high enough to force a charge into the battery, and yours is obviously adjusted too low. Normal voltage against a low battery should be at least 12.5, so increase the spring tension on the VR points first. Be sure the cutout relay points are clean, as oxidation there will limit charge current and give the voltage regulator a false indication of the battery's state of charge. Do you have an ammeter to monitor the charge current (not voltage) other than the one on the dash? It's VERY difficult to get a good regulator adjustment without being able to monitor both current and voltage.

The fact that the armature voltage goes up with the field grounded eliminates the generator as the source of the problem. If you're not able to adjust the regulator points and make the system charge, just replace the regulator assembly. There is no need to repair or replace a generator with those output numbers.
Jerry

Well that is not too bad. What is more inportant is the data you reported where you grounded the field and got 16 volt.
I agree with other guy (I forget name) that gen is probably OK and you have regulatorproblem



Dan Bentler

Well, fellows, I'm gone out again. I hope I can adjust the regulator ( I know I'm able) but I don't know if the regulator is able. Think positive, I've learned a lot from you two guys in the last couple of days. Exit-stage right. Keeping my fingers crossed and Thanks again. Steven

Boy, I wish I had a computer in my shop!

OK Hot Rod Lincoln. Here's the report. These are under (no load.) After increasing the spring tension Generator voltage at the (gen. is 16.5v,) On the voltage regulator- On the (battery term. voltage is 15.9v,) the (ARM. is 16.13v.) The voltage at the (battery is 15.50v.) / Now this is the only way I know to put a load on the system so I turned the headlights on high beam and the engine was at a pretty fast idle. Here are the numbers: Voltage at the (gen was 14.30v)-The voltage at the regulator was (Battery term.-13.85v) (At the ARM.term the voltage was 14.20v.) The (battery voltage was 13.50v.)THE LAST SET OF NUMBERS WERE UNDER A LOAD. The Volt/amp gauge needle moved to a point that it covered the the discharge side of the -0- on the gauge. It never moved any more than that. I can see that the system must be charging. Do you think that the gauge may need replacing? Again, thank you for being so patient with me and helping me with this problem. I could not have gotten this far with out you and "leitmotif." This again proves what a great place "Stovebolt" is. Thanks, Steven

OK- - - -progress! You're a little high on the voltage now, which will cause the battery to be overcharged if it's run for very long. Against a fully-charged battery (this is important!) the voltage needs to be adjusted to a reading of no more than 14.7 volts, measured at the battery posts, not the generator or regulator terminals. The voltage reading will reduce itself slightly when the regulator cover is replaced, due to better magnetic conduction through the steel cover than the open air while you're doing the adjustments. I like to adjust the voltage to about 14.8-14.9, and look for about 14.6-14.7 with the cover installed. Be careful not to let the cover touch the coil assemblies as you're replacing it- - - -a short will burn out a fuse wire built into the circuitry almost instantly.

Check on the ammeter response by leaving the headlights on, engine off, for about 10 minutes, then turn the lights off, start the engine, and rev it to a fast idle. The ammeter should deflect at least half scale toward the + side, and then gradually come back toward center as the battery recovers. One needle-width to the + side is about normal, 5 minutes after startup. A good-condition battery recovers very quickly after startup, and the charge rate drops dramatically. All loads are covered by the charging system BEFORE any charge goes to the battery, so lights, heater, radio, etc. will reduce the charge current available to recharge the battery, and make the ammeter hover near the midpoint, or maybe even go slightly to the discharge side. It sounds like your system is functioning pretty normally now, so all you need to do is tweak the final voltage adjustment a little. Good job!
Jerry

I dont like the near 2V drop between no load and full load. The term is droop all machines have it and is good thing but not in big doses.

I get the idea you do not have VOM which really hampers things. Here is why
You need to be able to adjust regulator to get correct voltage at full load. This means you need an ammeter on generator output to battery and a voltmeter on battery.

Headlights make a perfect load.

One more thing I would check with headlights on is volt drop on wire from gen to batt ie Gen X (+?)to batt X. I would look int the 0.7 volt drop.



As is 13.5 will be good enough at nite. BUT I would like daytme a bit closeer to 14.5

However you are getting close.



























xx







+

Let's get him in the ballpark before you go all high tech on him! Yes, he's got a dirty connection or two to deal with that are dropping too much voltage. A series resistance check and individual voltage drop measurement of every connection can come in due time. I'd suggest a specific gravity check over the next several weeks with monitoring of the electrolyte level to establish the optimum voltage setting to keep the battery charged without losing an excessive amount of water. That's how we kept 40-something batteries at peak efficiency in the fleet I maintained several years ago.
Jerry

OK boys, I'm on the road to getting things right, thanks to ya'll. I'll give another report later. I've got to put a battery in my Mother-in-Laws lawn mower and then I will get back to work on my truck. Thanks ever so much to both of you. Steven

Agree
Dan Bentler

Well, hello again my friends. I feel like I know ya'll.Anyway, here's the scoop. I removed the regulator cover,Started the engine and went around to the other side to read the voltage. It was around 15.5V. So I began loweing the voltage at the regulator while keepin a check on the battery voltage. To hit the mark of 14.8v-14.9v was not an easy task. I made a bunch of trips around the truck. I finally got 14.8v With the cover off and just as you said when I put the cover back on it read around 14.7 volts./// Now I turned the engine off and turned the head lights on for about 10 minutes. When I started the engine I got a small amount of movement to the + side of the center 0. I reved the engine a pretty good bit but it (the needle) never went over any more. I know it's charging but the gauge really doesn't show it. I know ya'll must be tired of foolin' with me. If you are it's OK. I am glad I found someone to help me. Take care till we meet again, Steven

Good on ya! It's nice to work with someone who is willing to listen, follow directions, and give an accurate report of his findings! I've been teaching auto mechanics as an on-the-job trainer, technical school, and high school instructor for about 40 years, and it's rare to find somebody who really listens! Electrical work is the hardest subject to teach, as it's not possible to watch those electrons go about their business! Engines, transmissions, steering and brakes- - -you can see them work and figure out what's happening.

The fact that you're getting pretty noticeable voltage changes at different places in the circuit indicates you've got some loose or dirty connections to deal with, but you're in the right neighborhood to keep the battery charged now. If you want to take further discussions to email or private messages we can work out a few more details with specific suggestions for dealing with those issues. Basically, every connection from the generator to the battery needs to be clean and tight. A good ground between the regulator base and the generator housing is vitally important. Run a dedicated ground wire if one's not there already. Don't worry much about the ammeter deflection- - - -it's not a very accurate gauge, just a rough indicator of "charge" or "discharge". If you want to shop ebay for a good-quality volts-ampere tester, they're available at some pretty reasonable prices. Being able to monitor current flow with an inductive ammeter is a big help to charging system work- - - -it eliminates a lot of guesswork when just using a voltmeter. That type of meter just clamps around a conductor to monitor current flow- - - -no need to disconnect wires and put the meter in series with the circuit like we had to do 50 years ago.
Jerry

Hey guys, this is a great thread. I don't mind at all seeing your correspondence continue on the open forum.

- Lonnie

Well, Hot Rod, I kinda hate for this to be over. I'm going to start at the generator and do as you said, clean and check everything for tightness. There is not a dedicated ground wire from the gen. to the regulator,yet. Today there will be. I've really enjoyed learning from you. As I said before, I'm 60 almost 61 years old and I've had a good time watching thing work when you do thing right. My friend, "Stovebolt" could not have a better or more patient teacher. Drop me a line now and then. Maybe I can give you some help or someone else that may need it. I know you probably won't believe this but I retired from an electric plant, but I was a mechanic for most of my time and then switched over to operations before I retired. Thank you ever so much and you too "leitmotif." I will get a volt-ampere tester soon. I had one but my Son needed it at his job so I give it to him. He's worth it, if he didn't have to work so much he would be over here helping me. Oh well, Take care and thanks again. When everything is done I'll file you a full report to your emaill address.

"I love it when a plan comes together"

Jerry

Connecting "grounds" aka bonds (technically more proper term) between regulator generator and battery would be ideal. I think # 10 or maybe 8 should be adequate.

If you go to battery post I would not only crimp the lug but solder it to keep acid out. Noalox on it and post would be good also.

Dan Bentler

The factory regulator/generator ground wire size is #18. All it has to carry is the current to operate the field coils, typically a square wave DC signal at less than 5 amps. The charge current grounding is done through the generator housing and the engine block. Since the regulator is mounted to the body, a dedicated ground between the generator housing and the regulator base assures that rusty body metal does not become the only path for field current to follow. I have some Delco training manuals for charging systems from the 50's and 60's. Would you like me to scan you a copy?
Jerry

Jerry, if it's not too much trouble. You and Dan have already been so much help I hate to ask you to do that. I've printed out all the both of you have sent me and I keep it in a notebook for future troubles. The book also has othe things Concerning my Stovebolt. I'll leave it up to you . Although it would be very good reading. Thanks a bunch, Steven

Red 49 Truck

This has been a great thread. I have the same problem that you had. I saw your update on your problem. Can you give me some more info on your fix? I looks like my problem is a duplicate of yours.

> Jerry, Dan, and anyone else - I welcome any additional input that wasn't covered in this thread.

My '54 was converted to 12v by a previous owner. The ammeter did not work from the day I bought it 10yrs ago. I assumed that it was fried, just like the gas gauge. The batt never went down so I figured that the charging circuit was OK. I didn't drive truck very much, and I hooked up a charger occationally just to "top off the charge" between drives. I'm ashamed to admit it, but I don't know if the system ever charged.

I'm restoring my gauges, so I checked the wiring to the ammeter. The wiring does not match the original Chevy wiring diagram. Looks like a wiring harness from one of the suppliers. Colors are not correct with the original Chevy wiring diagram. Most wires numbered.

ORIGINAL WIRING:
> A 10g wire from the Batt on the voltage reg went to one terminal of the ammeter, and a 18g wire ending near the horn, but connected to nothing, was on the other terminal. So the ammeter connection was open.
> A 10g wire feeds the light switch; I believe that it splits from the volt reg Batt.
> A 10g wire from the starter/battery fed the ign switch.

LONNIE'S REWIRING:
I rewired to conform to the Chevy wiring diagram, but something must still be wrong.

Ammeter does not show charge when engine is running. The ammeter shows discharge when engine off and headlights on. Voltage across battery is 12.6v no load. Voltage is 12.4v with engine running. Does not increase when I increase engine speed. I performed some of the tests that Dan and Jerry described.

AMMETER:
> "D" terminal to Starter/Battery and to horn relay "hot" terminal
> "C" terminal to Volt Reg Batt and to Ign switch "hot" terminal

IGN SW:
> "Hot" to "C" on ammeter
> Output to coil and to gas gauge "+"

LIGHTS:
> No change in hookup. I believe that the power comes from the volt reg batt.

I installed two different '54 ammeters. Both read the same.

What changes did you make to your wiring. Any tests or suggestions to get my truck charging?

I'm stumped.

Thanks,

Your description of the wiring connections sounds right; all we need to do is get the generator charging and I believe you'll be good to go. Take the cover off the voltage regulator and see if the contacts behind the "B" terminal close when the engine is started and the RPM raised somewhat above idle. I'm going to predict that they do not close. Be careful that you don't touch anything inside the regulator as you remove the cover- - - -it's steel, and one momentary short circuit is all it takes to fry stuff inside the regulator.

If the cutout relay is not closing, disconnect the Battery lead from the regulator, and use a piece of clean business card stock or a slice cut from a 3X5 inch index cards to burnish the points, all three sets of them. DO NOT USE A FILE OR SANDPAPER ON THE POINTS! All it takes is a very slight amount of oxidation on the point surfaces to keep the generator from charging. Once that is done, reconnect the Bat. wire, and use a short jumper wire to flash a momentary connection (less than 1 second) from the B terminal of the regulator to the A terminal. You'll get a moderate arc flash- - - -that's normal. Thos "polarizes" the generator, and should make it charge when the engine is started again. Voltage at the Armature terminal of the generator will rise above battery voltage, the cutout relay will close, and current will flow into the battery to keep it charged. Try that procedure, and let us know what the results are. With the generator turning and the cutout relay closed, terminal voltage at the battery should be 13.0 volts or more. When the engine stops, the cutout relay points should open so the battery cannot discharge back through the generator. Be ready to pull a battery cable connector off in case the points stick the first time you shut down, so don't tighten the cable clamps more than snug, at least for now.
Jerry

Jerry -

I followed your instructions, but still have the problem.

You were right -- the contacts on the Batt terminal of the volt reg did not close when I started the engine and increased RPMs.

I disconnected the neg lead to the battery instead of the Batt terminal of the volt reg. Then I cleaned all three sets of points in the volt reg with a business card. Had to hold the Batt points closed while I cleaned them.

Reconnected the neg battery lead and flashed the Batt and Arm terminals of the volt reg with a jumper.

Started the engine. The Batt contacts in the volt reg did not close at idle or at increased RPM. The instrument cluster ammeter did not show a charge when running. Voltage across the battery remained at 12.5v off/idle/increased RPM.

What's next? How do I check to see if the generator is generating?

I really appreciate your help and patience.

OK, next step- - - - -connect a small jumper wire from the F terminal of the generator to the generator housing with the engine running, being sure to get a good ground. If the generator is capable of charging, the voltage should increase without limit as the speed increases. If voltage does not rise, try disassembling the generator and inspecting the brushes. They should be long enough to contact the armature firmly and the commutator (the brass strips at the end of the armature) should be smooth and shiny. Clean it up with a piece of emery cloth and a shoeshine motion if necessary. Generator brushes aren't expensive or hard to install, and replacing them will cure a lot of charging problems. Good luck!
Jerry

Rats! Still no charge. I jumped the Field terminal on the gen to the housing on the gen at the bracket. Still 12.5v across the battery at all RPMs.

Here's the generator. See anything wrong? I painted it a few months ago. I tried to clean all spots that paint might insulate. (The black tag implies a 6v gen ... it's a fake that I riveted to the 12v gen.)

I may have to delay pulling the generator. I'm getting ready for a really great show in a few weeks. I'm working on windows, garnish, paint touch up, gauges, wheels, and a leaking carb, plus wax and detail. Too many irons in the fire! The truck will be able to make it to the show and back w/o a working generator if I don't get to it in time.

Thanks,

OK, your hookup is correct, Armature terminal on top with the big wire attached. That wire should go to the "A" terminal on the regulator, the one in the middle. The small "F" wire attaches to the corresponding terminal on the regulator. I still suspect the brushes, or possibly an open-circuited field coil. When you get a chance to tear the generator down, see if you can get a circuit from the F terminal to the insulated brush with the armature removed from the generator. Use either a 12 volt test light and a battery, or an ohmmeter. There should be approximately 20 ohms' resistance or less to the field coil circuit.

After polarizing, there is a small amount of "residual magnetism" that allows the armature to develop about 1/2 volt with no wires attached to the generator. The field circuit picks this voltage off the insulated brush, and creates a strong magnetic field when the "F" terminal is grounded either by the regulator or a jumper wire. This raises the voltage present at the "A" terminal of the generator and causes the cutout relay to close. If the voltage does not rise at the Armature terminal when residual voltage is present and the field is grounded, there's an internal failure in the generator.
Jerry

Jerry -

Thanks again for your time and help. The gen wires are connected to the correct terminals on the volt reg. I've been mentally going over the previous hookup to see if a wayward wire is causing the problem. Don't know how long it hasn't been charging. Looking forward to finishing the other tasks on the truck so that I can devote full time to the charging circuit. I hope to replace brushes before I drive the truck to avoid possibly scratching the armature.

OK Guys, I can end this thread now. I pulled the Dash gagues out,got the wiring diagrahm out and guess what? The wiring was WRONG!! I re wired it and started it up and it charges. Only problem is the gauge doesn't go back to the center. I even cut off my "battery cut off switch., so I know nothing is going to the gauges. Small problem. I need to center my needle or just live with it. I've learned so much from all of you. Thanks a bunch. Never overlook what someone else has done. Lesson learned. Thanks a bunch for taking the time to help me. It was not wasted. Steven

Good on ya! You stuck with the problem long enough to solve it. Sometimes it's necessary to remove the gauge cluster and (gently) bend the ammeter needle until it centers up on zero with no current passing through the gauge. Otherwise, just get accustomed to where the "no charge/no discharge" point is, and go from there. Other than being a minor annoyance, the meter failing to center won't cause any problems.
Jerry

Red 49 Truck - Since I hijacked your post, I'll end my part of the thread too ...

Like you, my ammeter was hooked up wrong. Jerry came to my rescue regarding my generator and confirming my gauge hookup. His diagnosis of my charging problem was right on - the brushes in my generator were shot. Didn't have time to learn how to tweek a generator, so I had a shop replace them and turn the armature. Now my generator is generating and my ammeter is metering.

Thanks Jerry for your help and thanks Red 49 Truck for letting me sidetrack your thread.