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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 14988
Experience:  Certified on Onan and Generac generators
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I have a Generac Home generator item # 0044562 serial #

Customer Question

I have a Generac Home generator item #(###) ###-####serial #(###) ###-####120/240 volt 100/50 amps 12000 watts. It will start upon no electric sense but runs for about 15 seconds and dies. Oil, heat sensors check ok. Checked stator windings all ok. The only thing I see is the red light on the voltage regulator is not illuminated. The windings are putting 6.9 volts dc to the brushes at wire 4 connector. Do you think my voltage regulator is bad. My battery blew up about a month ago , I replaced it and the unit started and exercised once. Nothing since unless the power goes out then start and stop
Submitted: 1 year ago.
Category: Small Engine
Customer: replied 1 year ago.
I'll go 30.00
Expert:  Hank F. replied 1 year ago.

Hello, my name is ***** ***** I am going to assist you with this.

The windings to not put voltage to the brushes, so disregard all of that.

Lets start at the beginning.

I have uploaded a test for you to do. I need you to do all of the steps in Test #4 - Fixed Excitation/Rotor Amp Draw, and let me know all of the results.

When giving the results, please tell me the wire numbers, not the step numbers. IE - Voltage across wires 2 and 6 was 30VAC, not Step 2 was 30VAC.

Disregard the charts in the test - they are for a different genset. But this test works better on your genset than the one that is in the book.

Click here to download the test.

Customer: replied 1 year ago.
41.1 on test 1
3.5 on test 2
13.6 on test 3
5.8 on test 4
Customer: replied 1 year ago.
Sorry on test 3 and 4 I was on voltage not amperageTest 3 was 4.6
Test 4 was 1.0
Expert:  Hank F. replied 1 year ago.

I did not give you a test 1, 2 or 3. I only gave you a test 4 - Fixed Excitation/Rotor Amp Draw.

The nubmers you have do not even correspond to any step numbers.

As per my last post, I need to know the wire numbers you tested, and the results.

Customer: replied 1 year ago.
Ok sorry for my miscommunication. Wire 2 to 6 reads 41.1 Ac while running
Wire 11 to 22 reads 3.5 Ac while running
These both were done with wire 4 connected to 15 for 12 volt supply
Wire 15 to 4 reads 4.6 amps Dc when generator is dead
Wire 15 to 4 reads 1.0 amps Dc when generator is running
Expert:  Hank F. replied 1 year ago.

Wow. Those readings are all over the place.

Give me about 10 minutes to think on this one.


Expert:  Hank F. replied 1 year ago.

OK. We are going to have to do everything manually here. Your numbers are just not showing anything - they are too spread out.

The first thing I need you to do is to remove the wires #4 from the VR.

Set your meter to ohms, on the lowest scale, and touch one lead to the wires #4 (you do not have to separate them). Touch the other lead to a good clean ground.

What reading do you get?

Be forewarned, after this, you are most likely going to end up having to do some major disassembly, so prepare yourself.

Customer: replied 1 year ago.
97 ohms
Expert:  Hank F. replied 1 year ago.

You should have gotten about 15.9 ohms. It looks like you have a shorted rotor.

At this point, you are going to need to tear down the entire left end of the genset, and inspect the rotor.

It would be a good idea to do a comprehensive testing of the stator while you have it out, also.

Customer: replied 1 year ago.
Do you think the battery exploding may have caused this to happen
Expert:  Hank F. replied 1 year ago.

Not a chance. The battery is on the right side of that divider panel, and the generator is on the left.

It is just a coincidence.

Customer: replied 1 year ago.
In your opinion is it worth rebuilding or just buy a new on. I can get a 14 k new for 2600.00. All the rotors I have seen are 800 to 1100 dollars
Expert:  Hank F. replied 1 year ago.

The rotor for your unit is about $300.

The part number is ***** - I already checked.

The part is currently listed as unavailable, which means the factory would have to build one. That usually takes 4 - 6 weeks.

As far as rebuild or replace, only you can make that decision.

But if yours has been pretty much trouble free, $300 to get it fixed is a lot cheaper than $2600 to replace it.

On the other hand, a new one will come with a warranty, will be somewhat quieter, and much more fuel efficient.

Customer: replied 1 year ago.
Can you give me the stator number also. I will be out of town this weekend but will tear it down Monday and get back with you
Expert:  Hank F. replied 1 year ago.

The stator number is *****

Customer: replied 1 year ago.
Hank, got the rotor apart and attached is a picture of the rings. On 2000 ohm scale after cleaning a spot on the rings up, I'm getting 20.1 ohms. Do I still need to pursue a bad rotor or do you think bad brushes could be the problem?
Expert:  Hank F. replied 1 year ago.

Those slip rings are burnt. They need to be cleaned up badly.

But - you have done something wrong somewhere. You can not get 0.97 ohms with burnt rings, and then 20 ohms with clean rings. It just doesn't work like that.

But if you are actually only getting 20 ohms, the rotor should be good. Clean up the slip rings, and check the brushes. If they are bad, clean or replace them.

Customer: replied 1 year ago.
Hank upon more inspection when the battery blew up it sent shards of plastic and lead into the stator where the cooling air enters the unit and has shorted and burnt the windings. Also the rings on the rotor are pretty scared up under the black. So it looks like replacement will be happening since I don't know what else electrically is shot. Thank you for your help very much!!!!
Expert:  Hank F. replied 1 year ago.

I don't see how the battery could have gotten in there. It is supposed to be on the other side of the firewall from the generator.

But if the slip rings are not perfectly smooth, it will lead to problems down the road. And if the stator is dmaged, you definitely need to do something.

Your 3 options are:

1. Buy new stator and rotor (I would suggest new brushes, also).

2. Have yours rewound

3. New genset.

Expert:  Hank F. replied 1 year ago.

Was this what you wanted to know?