Test My Generator

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The Riot
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Test My Generator

Postby The Riot » Tue Jan 14, 2014 6:08 pm

Does anyone have any suggestions on how I might go about testing my generator to see if it is working properly. Here's the rest of the story. I am totally rebuilding my 1972 Cub and the tractor is mostly disassembled. Currently the engine is about 80% back together, so the generator is removed and I can't turn it with the engine.
What I have tried is spinning it, like a top, with a string wrapped around the Pulley/sheve with my very modest and simple multimeter attached to both the A & F pole connectors. I was able to get it spinning pretty fast by wasn't picking up anything on the meter. I'm not sure if I even had the meter set properly, I'm guessing VDC.
Are there any simple tests I can perform on my gen that is not on a running engine?

Thank you in advance for you help,
The Riot

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Re: Test My Generator

Postby tst » Tue Jan 14, 2014 6:13 pm

There are 2 parts to the motoring test of a generator.

1) Ground the F terminal and apply 6/12 volts as appropriate to the A terminal. It should motor over.
2) Remove the ground from the F terminal. It should speed up.

I don't think this guarantees it will charge, but if it fails these tests, it will not charge.
Tim

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Re: Test My Generator

Postby Cecil » Tue Jan 14, 2014 6:41 pm

Go to Rudi,s manuals at the top of the page. Find the Maintenance tips and techniques. On that page there is a generator testing flow chart. Click and follow closely and you will find the problem.

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Re: Test My Generator

Postby BIGHOSS » Tue Jan 14, 2014 6:46 pm

I like to take the easy way out. Take the genny and VR to a local rebuild shop and get it tested on their machine for free. Or take it to your local Advance Auto, Auto Zone or any other parts house and let them test it free.

The reason that I go to my local rebuild shop is he can test the genny under load and tweak the VR to make it charge the correct volts. If the generator charges without the VR and not with the VR, then the VR is the problem.
We make a living by what we get, but we make a life by what we give......Winston Churchill

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Re: Test My Generator

Postby Scrivet » Tue Jan 14, 2014 10:24 pm

ndtheriot3030 wrote:.......the tractor is mostly disassembled. Currently the engine is about 80% back together, so the generator is removed and I can't turn it with the engine.
........
Cecil wrote:Go to Rudi,s manuals at the top of the page. Find the Maintenance tips and techniques. On that page there is a generator testing flow chart. Click and follow closely and you will find the problem.
Cecil, I don't think the flow chart is going to do much good with a generator sitting on the work bench.

I would start with Tim's advice on the "motor test". Easy to do at home with a battery and three (battery voltage to A terminal, battery ground to case, F terminal to case) pieces of 10 gauge wire. If you're unsure of the results or just want a second opinion then follow BIGHOSS to the genny rebuild shop :D . When you get it all back together and you have problems down the road remember Cecil's advice and follow the chart.

The Riot
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Re: Test My Generator

Postby The Riot » Wed Jan 15, 2014 10:56 am

Thank you all. I will try both methods. I'll try to make it spin, then take it over to the genny shop for their diag.

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Re: Test My Generator

Postby birddog » Wed Jan 15, 2014 6:17 pm

If you have a bench grinder with a wire brush wheel, it is ideal for spinning a gen. for testing.
Mark "birddog" Birdeau
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