Generator voltage output test??

[clarkede]

I have a small but significant problem and I'm hoping you or one of your viewers can help. I have a 1948 Plymouth Special Deluxe with a 6 volt positive ground system. I'm having problems with the charging system. I have taken the generator completely apart and cleaned "everything" inside. I then performed the "motor" test on it where I grounded the field wire and connected the battery to it and it runs "perfectly smooth." So I know everything in the motor seems right. I've confirmed that all the grounds related to the charging system are clean and well secured - including generator to the block; block to the battery; and I've added a dedicated ground wire from the frame to the voltage regulator (ground). I have replaced the voltage regulator on it twice - the current one I bench tested (two of the relays "engage" at around 6.8 add 7.2 volts respectively as I turn up the voltage slowly on my power supply). The battery voltage in the car at rest is around 6.24 volts. However, when I start the car the voltage does not increase at all - no matter what RPM I increase the engine to. I've tried both analog and digital multi meters. I've removed the generator, the wires and the voltage regulator - checked them and reassembled multiple times. Believe it or not, I had a bad Ammeter and had to replace it - now the Ammeter works fine - needle moves to negative when I turn on the key or headlights, but the needle does not move to the positive when it should be registering a charge.

So my question is this - Can I disconnect "all" the wires from the generator and start the car to confirm that it is putting out voltage, or will this fry the generator? I'm guessing that I should be able to start the car and see the voltage rise; then shut off the car quickly if the voltage creeps up to high. My suspicion is that the generator will show no voltage when I run the engine, but I'm not sure. Oh, I forgot to mention that after my rebuild of the generator, I questioned if my problem was the generator or the voltage regulator, so I took it to a motor repair place and they hooked it up in the back room and said it was in great condition. However, I failed to ask them how many volts it was putting out - if any. Maybe they just did a motor test and that was how they tested - I'm not sure. I'm hesitant to take it back because I hate to bother them when I feel I should be able to diagnose something as simple as this myself.  I also have the" Motor's Auto Repair Manual" and it is a wealth of knowledge in it, but it doesn't explain how to test the voltage output of the generator alone.  It only explains how to do the "motor" test to see it it works.  It also goes into ton's of information on the voltage settings for the Voltage Regulator, but that would assume it has ample voltage being generated. 

 

Any advice on how to confirm if the generator is putting out sufficient voltage would be great! Thanks!

[joecoozie]

Did you polarize the regulator/generator after removing and disassembling them?

 

"

How to Polarize 6 Volt Regulators Find your vehicle’s or machine’s volt regulator. It’s usually square, with five or six terminal screws on the side. If your regulator has five terminals, locate the terminal marked “A” on the regulator.

Connect your jumper wire to the battery terminal with a clip. You might also wonder how to polarize a 6v positive ground generator. Attach one clip to the A terminal of the generator to polarize a generator on a tractor with a Delco 6V positive ground system, a Lucas 6V or 12V positive ground system.

Tap the negative (-) terminal on the battery for a split second (or a spark occurs) in the other clip. Second, how do I put a 6 volt generator to the test? How to Test a 6-Volt Generator Turn on your car’s battery. It’s the simplest way to see if your 6-volt generator produces the correct voltage.

The 6-volt generator should be turned on in your car. To measure voltage, turn the dial on your multimeter. Place the metal rods on the battery terminals’ ends on the two wires from the meter. How do you polarize a Chevy generator in this context?

How to Polarize a 12-Volt Generator Remove the fan belt from your vehicle or machine before the generator starts. You may be able to remove it by hand; if not, use a socket set to loosen the sway bar arm. Connect the jumper wire to the generator’s armature terminal. Connect the positive terminal on the battery to the other end of the jumper wire.

Why is it necessary to polarize a generator? Polarizing is performed to ensure that the Generator and Regulator are operating and charging at the same time. Simply put, working together rather than against one another to ensure that the vehicle’s electrical system keeps you running. Both are negative and positive, but they both do the same thing."

[clarkede]

Yes.  I polarized the generator.  Also, when I took the generator to the motor repair shop the guy told me that he also polarized it and he assured me he did it for positive ground.  I meant to mention this as it is a common issue with generators.  Thanks.

[squirebill]

go to 'Youtube" search: Generator-How to bench test it while in your car.  Clear and concise and using a volt meter will tell you if it is putting out sufficient voltage.  Worked for me.  Regards.

[DJK]

I love my 6v positive ground alternator.?

[clarkede]

Where can I get a 6v positive ground alternator???  I seriously would consider it - especially if it fits with little to no modifications.

[clarkede]

I've seen a bunch of Youtube videos on the subject including the one called "Generator-How to bench test it while in your car".  His clear and concise video is great, except it was wrong about the Field wire on my the 6v generator for the1948 Plymouth.  I have a two brush generator, and in order to do a "motor" test you have to "ground" the Field wire - not connect it to the Armature terminal as in his video.  Originally, I did what he said and it was actually a short circuit.  Yikes.  That was why I finally took it into a shop right before they closed and they offered to quickly test it for me. 

 

I think I might just try and run the generator tonight without connecting it to the Voltage Regulator and see what kind of voltage it puts out.  I just wish I knew if this was advisable and why I'd like some advice from someone who knows.  I've seen videos mention that the voltage could go up to 40+, but I don't know what to look for other than that.  My goal ls just going to see if it will register over 7 volts or not.  Wish me luck.

 

[DonaldSmith]

I had my alternator made up by a local automotive electrical service company, many happy years ago.  The guy put the appropriate parts in the standard GM alternator.   You could check your local auto electric shops, if there are any anymore. 

 

But you can search on-line, "6 volt positive alternator", and find some vendors.  They also sell bracket kits.  Tell them what fan belt width you are using, so they can put on the right pulley. 

 

Wiring was simple.   I connected the Red? wire from the big post of the generator to the single post of the alternator.  I abandoned and removed the Green? wire from the small post to the "F" post of the voltage regulator.  

 

At the voltage regulator, I removed the Red? wire from the "A" post and the Black? wire from the "B" post, and connected the two wires together.   I removed the voltage regulator.  (You could keep it for the vintage look.  You could attach coils of wire to it, to confound the onlookers.)   

 

My car, the upscale DeSoto Custom, had a Brown? wire from the starter solenoid to the small post of the generator.  This was to ground the solenoid relay through the generator.   Chrysler's trick was that if the engine were running. the the generator would no longer provide a ground, and the starter would not grind.  I gave up this feature, and grounded that wire from the starter solenoid.      

[keithb7]

My understanding is If you remove all the wires from a generator, then it wont create any output amps. The field coils are not energized if you remove all wires. The armature also gets opposite polarity. Current traveling through the field windings create an invisible magnetic field. I think the armature slices through the field winding’s magnetic field. Opposite polarity energized atoms are interacting. This creates DC amps. Lots of them. Depending on how many feet of looped of wire are in the field windings. 
 

A generator starts out with small amps feeding it. It gets excited, and then creates big amps!  In principle it functions like a starter.

 

When you polarize a generator you are just making sure the field windings are very excited, at the proper polarity. So when the armature's magnetic field cuts through the field winding's magnetic field, you get lots of out put amps! How much it puts out, is controlled by the regulator. 

Or something like that...I'm no electrical engineer. The details are foggy.

 

I quickly and easily measured my generator output. Seen here. 

 

 

Edited September 21, 2022 by keithb7

[Sam Buchanan]

6 hours ago, clarkede said:

Where can I get a 6v positive ground alternator???  I seriously would consider it - especially if it fits with little to no modifications.

 

https://www.ebay.com/str/howardent
 

 

[clarkede]

On 9/20/2022 at 10:01 PM, keithb7 said:

My understanding is If you remove all the wires from a generator, then it wont create any output amps. The field coils are not energized if you remove all wires. The armature also gets opposite polarity. Current traveling through the field windings create an invisible magnetic field. I think the armature slices through the field winding’s magnetic field. Opposite polarity energized atoms are interacting. This creates DC amps. Lots of them. Depending on how many feet of looped of wire are in the field windings. 
 

A generator starts out with small amps feeding it. It gets excited, and then creates big amps!  In principle it functions like a starter.

 

When you polarize a generator you are just making sure the field windings are very excited, at the proper polarity. So when the armature's magnetic field cuts through the field winding's magnetic field, you get lots of out put amps! How much it puts out, is controlled by the regulator. 

Or something like that...I'm no electrical engineer. The details are foggy.

 

I quickly and easily measured my generator output. Seen here. 

 

 

 

I did not remove any of the wires to test the Voltage Regulator after all - as your advice sounds right and it would not output anything anyway.  I also watched the video which has some great info in it.  Thanks for sharing!!!

 

Tonight I tested voltage and it was 6.35 volts with engine off.  Then I started the engine and the voltage stayed relatively steady at about 6.25 volts.  There was a little movement as I increased the RPM's to about 2500, but I believe the voltage actually went down and not up.  Unless someone has some ideas I think I'm going to have to take the generator back to the motor repair shop and see if they will test it again on the bench and tell me what the actual output voltage and amps are. 

 

Thus far, here's everything I've tried to get the generator to charge my battery:

• Rebuilt/inspected the generator

    - Took the generator apart and cleaned/de-greased it inside and out.

    - Cleaning out the mica between all the contacts in the armature

    - Polishing armature (looks like shiny copper now)

    - Checked the brushes and cleaned the inside wire terminals where the brush connect

    - Lubricated the armature bushings

    - Cleaned the outside Armature and Field terminals

    - Tested the generator as a motor by shorting the Field terminal to ground(+) and connecting the Armature to battery(-) = Ran smooth.  Not sure of RPMs but I would

"estimate" a couple hundred RPMs(?)

    - I POLARIZED the generator. (everyone asks) :)

• New wires and new connectors to the voltage regulator

• New Voltage Regulator (Standard VR-2)

    - The original Voltage Regulator seemed fine, however,

    - I bought a new Voltage Regulator.  I returned it because it wasn't charging the battery (I suspected it was dead on arrival),

    - I re-bought another new Voltage Regulator. 

    - This makes 3 Voltage regulators all with the same results of "not charging"

    - I've bench tested the Voltage Regulator with variable voltage and I see two of the relays engage (close contacts) at about 6.9v and 7.8 volts respectively.

• New Ammeter installed.  Old one didn't work (needle didn't move at all, even after trying to repair it. Shunt must have failed)

    - Ammeter registers negative when I turn on the key, lights, heater, etc. 

    - Ammeter does not register any charge when the engine is running (at 1500+ RPMs).  I know it won't charge at idle RPM.

 

• Other facts (related to electrical system that might be relevent):

    - I completely rewired the car from head to toe and installed two Fuse Blocks after ammeter.

    - One fuse block for Key-On devices, such as ignition, heater fan, fuel gauge, wipers, etc.

    - One fuse block for Always-On devices such as brake lights, cigarette lighter, interior lights, clock, etc.

    - I rewired brake and parking lights for turn signals

    - I ran "return" ground(+) wires back to Fuse Blocks for all lights, wipers, and devices that I could.

    - All electrical devices work as expected with no strange behavior that would indicate something amiss

 

One-by-one, Plan to do the following.  If anyone has any test or pictures/videos that they would like me to post, let me know.

1. I plan to take the generator out and take it apart to inspect - AGAIN.

2. I plan to retest the generator as a motor - AGAIN.  Is there more than one type of test I could do???

3. I Plan to take the generator back to the motor repair shop for them to bench test it again.

4. I will give up and look into the 6v Alternator mod. 

 

Thanks for any advice anyone can give.

 

 

I just can't figure out why it runs as a motor, but won't put out enough voltage as a generator to charge the car. 

[Sam Buchanan]

Once you get fed up messing with the generator and regulator and start shopping for an alternator please be advised that the ones from the link I posted include shipping in the posted price. This makes these alternators very competitive with other vendors.

[clarkede]

1 hour ago, Sam Buchanan said:

Once you get fed up messing with the generator and regulator and start shopping for an alternator please be advised that the ones from the link I posted include shipping in the posted price. This makes these alternators very competitive with other vendors.

Thanks!  That's good to know about the shipping.  I've spent the last couple hours researching generator to alternator conversions.  This looks so simple and I'm thinking it might be the way to go (and just give up on the generator). 

 

Therefore, it looks like I would need a 60A, 6Volt, Positive ground Alternator with a bracket and the right size pulley (I think I have a 5/8" pulley, but I'll check).  The single wire that comes out of the Alternator would simply connect to the wire coming from my Ammeter, right? That way it would show if it is charging or not. 

 

Now... do I choose a black or silver color?  that is the question. 

 

It looks like you've converted yours to Negative ground (according to the battery cable colors)?  Any special reason for that?

 

 

[Sam Buchanan]

Just to make it more “conventional”.  ?

[DJK]

11 hours ago, Sam Buchanan said:

Once you get fed up messing with the generator and regulator and start shopping for an alternator please be advised that the ones from the link I posted include shipping in the posted price. This makes these alternators very competitive with other vendors.

Also includes the mounting bracket if I remember correctly.

[DJK]

[Sniper]

59 minutes ago, DJK said:

 

Doesn't load

[DJK]

23 hours ago, Sniper said:

 

Doesn't load

I copy and pasted, what am I doing wrong?

[Sniper]

At the bottom of the reply widow is a link labeled "choose files" click on it

 

It will open up a window on your computer that will let you select the file you want to post, double click on that file and it will upload the picture into your post, assuming it is under 3mb in size.  If it's too big you will need to resize it.

 

Or you can left click on the picture and drag it to the paper clip in the bottom of the reply window, again, 3 mb max size.

 

[DJK]

Thanks Sniper. I am electronically challenged!!!!

[clarkede]

On 9/28/2022 at 9:07 AM, DJK said:

Thanks Sniper. I am electronically challenged!!!!

Thanks DJK.  That image confirms my research and the only thing I'm going to do differently (Step 9) is run the wire from the alternator right to the ammeter (and bypass the voltage regulator).  I just ordered the 6 Volt, Positive Ground Alternator (with bracket and Pully).  I'm excited to get it and install it and hopefully my charging issues will be gone.

 

I still don't know why the generator wasn't charging.  Perhaps I got several Voltage Regulators that were DOA in a row.

Edited September 29, 2022 by clarkede
I was planning to purchased alternator, but now I've purchased it!

[Sam Buchanan]

I inserted a 60a fuse between the alternator and ammeter (where the regulator used to be) so the fat wire going to the alternator, and the alternator itself would be protected from a dead short to ground. I removed the old regulator and instead of running an alternator wire directly to the ammeter the output side of the fuse is connected to the wire going to the ammeter where it enters the harness.

 

The fuse may be overkill but if the alternator shorts out the fuse will prevent the big alternator wire from glowing red hot or melting the wire under the dash at the ammeter! I didn't run the numbers but I think the fuse would blow with a dead short even though it is oversized for the harness wiring.  

 

You will really, really like your alternator.....install and forget.  

 

Edited September 30, 2022 by Sam Buchanan

[kencombs]

Have you tried grounding the field terminal with the engine running?   That should cause the generator to output its' max charge as it eliminates the VR from the system.

[clarkede]

1 hour ago, kencombs said:

Have you tried grounding the field terminal with the engine running?   That should cause the generator to output its' max charge as it eliminates the VR from the system.

No I haven't. Your the first to recommend an actual test like this.  I've got a couple weeks until the new Alternator arrives and I am really curious if the generator works. I wasn't sure what wires I could short to test it.  I saw someone elude to this in some posting, but I didn't want to fry anything by shorting the wrong wire.   I will try this tomorrow evening if it isn't raining too much from Hurricane Ian.  I'll let you know what results show.

[DJK]

15 hours ago, clarkede said:

Thanks DJK.  That image confirms my research and the only thing I'm going to do differently (Step 9) is run the wire from the alternator right to the ammeter (and bypass the voltage regulator).  I just ordered the 6 Volt, Positive Ground Alternator (with bracket and Pully).  I'm excited to get it and install it and hopefully my charging issues will be gone.

 

I still don't know why the generator wasn't charging.  Perhaps I got several Voltage Regulators that were DOA in a row.

I just went out and looked at mine, I spliced into the black wire that previously went to the VR and ran that to the alternator, ammeter works fine.