Cub Cadet 122 overcharging battery

[save_old_iron]

One last test ...

reconnect the wire to the SG "F" terminal.

Now disconnect the wire from the "F" terminal of the regulator and perform the same check on battery voltage as I outlined before.

Doing this test will check to see if the field wire leading from the reg to the SG may be shorted to the chassis somewhere - simulating the reg calling for battery charging from the SG.

If the battery voltage still remains around 12.6 with the wiring disconnected from the "F" terminal of the regulator, the regulator IS calling for the SG to charge the battery and IS the issue.

Open up the case on the regulator and check the relay that already has closed contacts. You may find those contacts are stuck together and may require gentle prying to open them up to allow cleaning the pitted contacts.

[Yosemite Sam]

Please understand that I am not trying to say that anyone's recommendations are wrong, I'm just trying to install this information in my head in a manor that I can keep straight and understand.

Please correct me if I am wrong with my thoughts...

If the "F" terminal on the S/G was shorted inside the case (or anywhere else) wouldn't the S/G be slow and sluggish when turning the engine over?

And, if the wire on the "F" terminal were taken off and the engine were running (or not), wouldn't the voltage be "actual battery voltage" no matter where it was measured (providing there was a positive wire/post/terminal and a ground source)?

[J-Mech]

Originally Posted by Yosemite Sam

If the "F" terminal on the S/G was shorted inside the case (or anywhere else) wouldn't the S/G be slow and sluggish when turning the engine over?

Yes, that is correct.

Originally Posted by Yosemite Sam

And, if the wire on the "F" terminal were taken off and the engine were running (or not), wouldn't the voltage be "actual battery voltage" no matter where it was measured (providing there was a positive wire/post/terminal and a ground source)?

Yes that is correct. Which is what saveoldiron is saying. Here it is in bold.

Originally Posted by save_old_iron

Now disconnect the wire from the "F" terminal of the regulator and perform the same check on battery voltage as I outlined before.

Doing this test will check to see if the field wire leading from the reg to the SG may be shorted to the chassis somewhere - simulating the reg calling for battery charging from the SG.

If the battery voltage still remains around 12.6 with the wiring disconnected from the "F" terminal of the regulator, the regulator IS calling for the SG to charge the battery and IS the issue.

When talking about battery voltage he refers to it as 12.6. I read and reread this last night... and I agree it was kind of unclear. But it is correct.

[save_old_iron]

Originally Posted by Yosemite Sam

If the "F" terminal on the S/G was shorted inside the case (or anywhere else) wouldn't the S/G be slow and sluggish when turning the engine over?

Think about the relays in the regulator. When the engine is in the off state (SG is not being spun), the CUTOFF relay has open contacts and the REGULATOR relay has closed contacts. These are the normal "OFF" positions the relays assume due to their mechanical design. With the REGULATOR relay contacts closed by default, the field terminal is grounded thru the regulator assy - even with the engine off or while the engine is cranking.

The REGULATOR relay contacts stay closed (field grounded) unless over voltage or over current conditions are encountered. Excessive voltage or current thru the REGULATOR relay will increase the magnetism in the relay until the magnetism pulls on the relay contacts and opens them up - stopping power generation from the SG motor, preventing damage to the battery by over voltage and damage to the SG motor by drawing too much current from the SG motor. When the power generated from the SG falls below the threshold for the REGULATOR relay to hold the field contacts apart, the relay closes the contacts, full fields the SG and the SG goes to max output again. This happens so quickly the relay seems to buzzzzzzz. This rapid on and off cycling slams the SG on and off hundreds of times per minute and is what causes the relay contacts to eventually pit and fail.

I am working on a step by step tutorial explaining the operation of the SG and the REG. With my home life being so busy lately, I haven't made much progress. I will promise you it will be completed in the coming weeks.

[J-Mech]

Originally Posted by save_old_iron

Think about the relays in the regulator. When the engine is in the off state (SG is not being spun), the CUTOFF relay has open contacts and the REGULATOR relay has closed contacts. These are the normal "OFF" positions the relays assume due to their mechanical design. With the REGULATOR relay contacts closed by default, the field terminal is grounded thru the regulator assy - even with the engine off or while the engine is cranking.

The REGULATOR relay contacts stay closed (field grounded) unless over voltage or over current conditions are encountered. Excessive voltage or current thru the REGULATOR relay will increase the magnetism in the relay until the magnetism pulls on the relay contacts and opens them up - stopping power generation from the SG motor, preventing damage to the battery by over voltage and damage to the SG motor by drawing too much current from the SG motor. When the power generated from the SG falls below the threshold for the REGULATOR relay to hold the field contacts apart, the relay closes the contacts, full fields the SG and the SG goes to max output again. This happens so quickly the relay seems to buzzzzzzz. This rapid on and off cycling slams the SG on and off hundreds of times per minute and is what causes the relay contacts to eventually pit and fail.

I am working on a step by step tutorial explaining the operation of the SG and the REG. With my home life being so busy lately, I haven't made much progress. I will promise you it will be completed in the coming weeks.

Although this is a text book description of how a voltage regulator works.... You really didn't answer the question.

And for the record, after reading my old electrical book, I am going to retract my statement, and say that a short inside the SG causing the fields to be permanently grounded will not cause it to spin hard on starting. I am going to base that on the fact that (save_old_iron's description and the book description match, not that I doubted, but the books reads a little easier) the way a regulator is wired, the field coil is grounded all the time in a non-generating situation. The reason that it doesn't pull very hard on the motor is because there isn't enough voltage produced by just the battery during starting to pull on the generator to slow it down. After starting the higher voltage produced by the gen stays in the gen's winding which creates a "load" on the pulley as it starts to generate power. Does that make sense?

save_old_iron: It is clear you have a very good understanding of what you are talking about. Perhaps, try to answer a yes or no question, without a "how it works" description. You are diving in pretty deep when it probably isn't necessary, and it is causing frustration and confusion. Most people don't need to understand how the regulator works, just want to know if it is or isn't. So, explain how to test it, without going into the "engineering" world of it's internal workings. This will save frustration on all ends. Thanks, though! You do understand these things well! For those of us who are interested in "how it works" descriptions, I look forward to your write up!

[save_old_iron]

Originally Posted by J-Mech

Although this is a text book description of how a voltage regulator works.... You really didn't answer the question.

If you want to address a problem only on a Yes / No basis, the IH service manual does a great job of keeping it at a simple level.

I believe the simplest universal test is remove the field wire - does overcharging stop - yes , then replace the regulator.

But we already did that.

No need to replace the SG because it is capable of overcharging the battery - that just confirms it is good operating condition.

Owner says the wiring is good.

That's as far as I can go on a Yes and No level.

[IACubCadet]

saveoldiron- I agree with you, your help has really helped me along in trying to figure this out. I apologize for taking so long to get back to this issue. I see nothing wrong in what you have told me (and I think you are explaining it in a way that I understand). Thank you again for your suggestions and help.

I have not tried your suggestion yet of removing the F terminal wire from the regulator, but I will my next free minute in the shop. And if the voltage from the battery is 12.6 (at an "off state" if that makes sense) while running, it's a faulty regulator?

[cubfixer]

Did you install a NEW VR or a used VR? If you have tried a used VR, cut your losses and install a NEW VR. See if that cures it. I know that a used VR is cheaper than a used VR, but lets solve the problem.