How to test old Auto-Lite 6 volt generator

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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Jim Gordon
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How to test old Auto-Lite 6 volt generator

Post by Jim Gordon » Thu Oct 29, 2009 9:39 pm

Can a 6 volt generator be tested on the bench without breaking it down? Bearing feel good, brushes appear OK, commentator clean with under cuts. I believe I recall hearing that a gen can be hooked up to a 6 volt battery and it will turn over. And what if feasible does that prove? Is there away to determine the amp output? Can I put it on my jeep and see what happens or will I :oops: do damage to something. Very confused. I hate to take it to a shop. Any sites I can visit and educate myself? Learn so much from this site and the great advice. Jim


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Re: How to test old Auto-Lite 6 volt generator

Post by Cuz » Thu Oct 29, 2009 9:54 pm

Fasten generator to your bench top. Connect hot + 6 volt cable to generator's hot + Arm terminal (usually the larger terminal stud). Hold the battery's negative cable tightly against the generator's frame. It should spin up just like an electric motor.

As for determining it's compatibility with your jeep's electrical system you must know if you have an A or B circuit system and if the generator is an A or B circuit generator.

There's an excellent and very informative explanation of how this is done at Dr. Vern's web site.
http://vernco.com/sparks/id569.htm" onclick="window.open(this.href);return false;

Once you have determined the generator and your jeep's electrical system are a match then you can test the generator output right on your jeep.
Last edited by Cuz on Thu Oct 29, 2009 10:15 pm, edited 1 time in total.
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Jim Gordon
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Re: How to test old Auto-Lite 6 volt generator

Post by Jim Gordon » Thu Oct 29, 2009 10:02 pm

CUZ
Thanks for the advice and prompt information. Will review Dr. Vern site and exercise some of the gray matter. J.

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Re: How to test old Auto-Lite 6 volt generator

Post by Schultzd » Fri Oct 30, 2009 5:10 am

Or, just bring it to an auto electric shop. They tested both my gen and VR together to make sure they were compatible. It only took minutes and the guy didn't even charge me! (seems he is strong supportor of vets and their jeeps).

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Re: How to test old Auto-Lite 6 volt generator

Post by Jim Gordon » Fri Oct 30, 2009 10:10 am

Now that the type of answer that is rare but it wonderful to read. thanks for the comment, still will study but thanks again for the assist. J.

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Re: How to test old Auto-Lite 6 volt generator

Post by Jerry Hudgens » Fri Oct 30, 2009 8:50 pm

If you really want to test it on the bench, take an old washing machine motor or any other fractional horsepower motor that you have handy and rig it up with a pulley and belt to drive the generator. Then connect a couple of headlights to the output of the generator (Armature and ground). Then take a small DC power supply that you can control the voltage that is around 4 to 6 volts with a maximum current of around 3.5 amps. Apply the DC power supply to the field terminal and ground. Turn your washing machine motor on and turn up your DC power supply to around 3 volts with no load on the generator (Armature lead). After you measure the no load voltage you can then connect the headlights and measure the load voltage and current. Of course you need a DC voltmeter and DC ammeter to do this but most guys have a multi-meter which will measure the output up to about 10 amps. I used a shunt on mine to measure greater than 10 amps. If the generator puts out say 10 amps with your particular setup and there is no severe sparking at the brushes and the generator stays cool after an hour running with a 10 amp load, then you can be sure the genrator is working fine.

You should get about the following readings:

Speed Field Voltage Output Voltage Output Current
850 RPM 3.65 Volts 6 volts 0 (No Load)
1140 RPM 3.65 Volts 8.0 Volts 0 (No Load)
1725 RPM 3.65Volts 11.9 Volts 0 (No Load)
1725 RPM 4.6 Volts 8.4 Volts 21 Amps

By connecting the headlights in series and parallel you can change the load to get different output currents.

You can judge from this data about what you should be getting at the speed of your particular motor. Its really not that hard to do. Takes a little time to rig up the motor drive and belt but you can really test your generator correctly this way with quantitative results.

Jerry Hudgens 42 GPW

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Re: How to test old Auto-Lite 6 volt generator

Post by Graham1942 » Tue Sep 15, 2020 2:10 pm

When bench testing the generator as described do you put a jump wire between the armature and field terminal first then earth the case and then hold a wire from the positive battery terminal to the armature terminal on the generator.?

Thank you

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Re: How to test old Auto-Lite 6 volt generator

Post by Graham1942 » Tue Sep 15, 2020 2:11 pm

When bench testing the generator as described do you put a jump wire between the armature and field terminal first then earth the case and then hold a wire from the positive battery terminal to the armature terminal on the generator.?

Thank you

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Re: How to test old Auto-Lite 6 volt generator

Post by Adam » Tue Sep 15, 2020 6:56 pm

this post is ages old, wonder if any of these guys are still on here, Dr Vern, have not heard his name since JP magazine went away,, he is probably at DQ getting a burger,

Somebody may answer your question. you can also search for motoring a generator, usually they work ok in the vehicle if they work when motoring them.

Adam

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Re: How to test old Auto-Lite 6 volt generator

Post by Graham1942 » Tue Sep 15, 2020 11:46 pm

Thank you.

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Re: How to test old Auto-Lite 6 volt generator

Post by Adam » Wed Sep 16, 2020 5:40 am

If you go to the jeep draw page there is some information there on generators and regulators, couple recent posts there too. There are also different ways to test a b circuit and an A circuit generator. you can also search on this forum as testing and troubleshooting is gone over a few times.

I have not read all the posts totally, I dont know how a fractional hp motor will turn a generator that requires a couple horsepower driving it to make it operate properly, I test them on a running motor on a test stand.

Back in the day, when i was young and dumber, I tried running a generator on a test stand with a 4 hp gas engine, when generator got full fielded, it ripped the mounting screws from the test stand and went bouncing across the table, sooooo watch your fingers and dont use a wooden test stand.

Adam

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Re: How to test old Auto-Lite 6 volt generator

Post by Wolfman » Wed Sep 16, 2020 6:12 am

I made Alt./Gen. test stand out of a belt driven belt sander.
Belt sander died so took it off the top. Motor was underneath.
Made a bracket to mount the test subject to on top and belt it up.
Wire the alt/gen. accordingly and spin it up.
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