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On a Gravely Pro-Turn 148 with a Kawasaki 691V engine I've replaced the voltage regulator because my battery drains after a few mows of my 3 acre lot. The stator is sending 33 AC volts to the new regulator, but the B+ post on the regulator is registering only 11.9 DC volts output (if I'm testing it correctly). Here's how I'm testing it: With my multimeter red lead on the B+ post of the new regulator, and the engine on full throttle, I put the black multimeter lead on the positive terminal of my battery. This is a method I saw explained in another forum. With that I'm getting 11.9 DC volts. Huh!?

This is the second new regulator that is reading that way. I assumed I had bought a faulty new one and tried again from a different vender. But now I'm getting the same results :-(

Is it possible (I seriously doubt it) that I've bought 2 bad regulators in a row? Naaa. What do you think is up?

How should I be testing my voltage regulator/rectifier?

B terminal on the rectifier to - terminal on the battery.
+ terminal on the battery to the case of the rectifier
B to rectifier case.
The rectifier needs to be grounded to the mower to complete a circuit.

With the engine running full throttle connect the red lead to the B+ terminal of the regulator, and the black lead to the negative post of the battery. What is the voltage. Should read battery voltage. Now mow the red lead to the metal housing of the regulator while still keeping the black lead on the negative post what is the voltage. Any voltage over a about 1 volt indicated bad ground to the regulator and battery voltage would mean no regulator ground.

Just trying to make sure you are actually getting battery voltage to the regulator and not just creating a circuit that may not be there, and making sure the regulator is grounded.

ILENGINE said:

With the engine running full throttle connect the red lead to the B+ terminal of the regulator, and ...

Just trying to make sure you are actually getting battery voltage to the regulator and not just creating a circuit that may not be there, and making sure the regulator is grounded.

Click to expand...

OK great. I will try it out in the morning and post results. Thank you!

bertsmobile1 said:

B terminal on the rectifier to - terminal on the battery.
+ terminal on the battery to the case of the rectifier
B to rectifier case.
The rectifier needs to be grounded to the mower to complete a circuit.

Click to expand...

I appreciate the answer very much but I didn't really understand it.

Same as what Ilengine said
You need to read between the + terminal on the rectifier to the negative terminal on the battery and also to a ground point like the case of the rectifier.
If your mower has a plastic blower housing and the rectifier is bolted to the plastic housing then it might not be grounded.
The grounding straps get broken or fall off.

If the ground is bad the power terminal on the rectifier will still read 13V between it an the batteryBut if there is no ground then there is no circuit so the amps are sitting there all dressed up with nowhere to go.

bertsmobile1 said:

Same as what Ilengine said
You need to read between the + terminal on the rectifier to the negative terminal on the battery and ...

If the ground is bad the power terminal on the rectifier will still read 13V between it an the batteryBut if there is no ground then there is no circuit so the amps are sitting there all dressed up with nowhere to go.

Click to expand...

Thank you for such a thorough explanation! I'm headed out right now to test everything as advised. I'll post my results shortly.

And the results are:

With the multimeter set on DC volts, the red lead on the B+ post of the rectifier, and the black lead to the - terminal of the battery, I get 00.0 volts.
With the red lead on the rectifier metal case, and the black lead to the - terminal of the battery, I get 00.0 volts.
With the red lead on the B+ post, and the black lead on the positive terminal of the battery, I get 11.9 volts.
With the red lead on the rectifier case and the black lead on the + terminal of the battery, I get 12.3 volts.
And yes, I have the battery terminals correct in my test.

Any more suggestions would be greatly appreciated!

Test results show that the regulator is grounded but you are not getting power from the battery to the B+ terminal of the regulator therefore it won't charge. Try running a temporary wire 16 gauge or larger from the B+ terminal to the positive post of the battery and see what what voltage you get when testing the charge at the battery terminals.

ILENGINE said:

Test results show that the regulator is grounded but you are not getting power from the battery to the B+ terminal of the regulator therefore it won't charge. Try running a temporary wire 16 gauge or larger from the B+ terminal to the positive post of the battery and see what what voltage you get when testing the charge at the battery terminals.

Click to expand...

Ok I will. First I'm going to clean the connection between the positive battery cable and where it connects at the engine (I think it's the alternator). I'll report back in a while. Thanks!!

ILENGINE said:

Try running a temporary wire 16 gauge or larger from the B+ terminal to the positive post of the battery and see what what voltage you get when testing the charge at the battery terminals.

Click to expand...

Since cleaning the positive battery cable connections on both its ends didn't fix the problem, I'll be trying your B+ to battery bypass-wire test tomorrow morning. Once again, I'll be posting my results after that. BTW, my positive battery cable does have continuity -- FYI.

ILENGINE said:

Test results show that the regulator is grounded but you are not getting power from the battery to the B+ terminal of the regulator therefore it won't charge. Try running a temporary wire 16 gauge or larger from the B+ terminal to the positive post of the battery and see what what voltage you get when testing the charge at the battery terminals.

Click to expand...

When I run a 14 gauge wire between the B+ post and the positive terminal of the + battery terminal I get a ton of sparks. So I disconnected immediately for fear of ruining something. My connecting wire is not touching anything else. What am I doing wrong?

If trying to connect to the battery with the engine running could produce sparks since there is the potential for about 15 amps. If trying to connect with the engine off and getting sparks would indicate a short most likely the regulator shorted to ground, but some regulator are only half wave rectified so a shorted stator could also be an issue.

ILENGINE said:

If trying to connect to the battery with the engine running could produce sparks since there is the potential for about 15 amps. If trying to connect with the engine off and getting sparks would indicate a short most likely the regulator shorted to ground, but some regulator are only half wave rectified so a shorted stator could also be an issue.

Click to expand...

Connecting to + battery terminal from regulator/rectifier B+ post with the engine OFF creates NO sparks at all.
So what do you suggest I might do now?

BTW, I tried a new battery cable just for grins. Did not fix the issue. Bummer.

pict1000 said:

Connecting to + battery terminal from regulator/rectifier B+ post with the engine OFF creates NO sparks at all.
So what do you suggest I might do now?

Click to expand...

Since you are NOT getting sparks with the engine off, go ahead and make the connections between the regulator B+ and the positive of the battery, and then start the mower and check the voltage at the battery to see what you get.

Your issue is you are not getting power from the battery to the voltage regulator through the wiring harness of the mower. Could be a bad connection at the key switch, or an amp meter or some other connection that the charge system goes through. Would need the wiring schematic to follow the path.

And if the battery to regulator allows the battery to charge there is nothing that says that you cannot make it permanent. It will not discharge the battery and that is the preferred method anyway to connect the regulator to the big post on the battery side of the the starter solenoid.

ILENGINE said:

Since you are NOT getting sparks with the engine off, go ahead and make the connections between the regulator B+ and the positive of the battery, and then start the mower and check the voltage at the battery to see what you get.

Click to expand...

Sounds good. I'll give it a shot in the morning. I can't thank you enough for your help!!!

ILENGINE said:

Since you are NOT getting sparks with the engine off, go ahead and make the connections between the regulator B+ and the positive of the battery, and then start the mower and check the voltage at the battery to see what you get...

Click to expand...

Do I leave the existing battery cable as is while I'm doing the 14 gauge wire bypass? Or disconnect the battery cable first?

Here is my wiring diagram (I've checked 2 of the fuses -- continuity is good for both):

You can leave it connected to the battery, just don't let the end that was connected to the B+ terminal contact anything metal and cause a short. Also it looks like the purple charge wire should be directly connected to the positive side of the battery. But there appears to be a 20 amp fuse in that wire. If that fuse(small chance) is blow or corroded(larger chance and possibly melted fuse holder) will cause the issues that you are having with the charging system.

This bypass wire is just replacing the purple wire in the diagram. If you get the temporary wire connected and it then charges then we know that the problem is in the purple wire. And you can go ahead and use your temporary wire as the direct replacement for the purple wire.

ILENGINE said:

You can leave it connected to the battery, just don't let the end that was connected to the B+ terminal contact anything metal and cause a short. Also it looks like the purple charge wire should be directly connected to the positive side of the battery. But there appears to be a 20 amp fuse in that wire. If that fuse(small chance) is blow or corroded(larger chance and possibly melted fuse holder) will cause the issues that you are having with the charging system.

This bypass wire is just replacing the purple wire in the diagram. If you get the temporary wire connected and it then charges then we know that the problem is in the purple wire. And you can go ahead and use your temporary wire as the direct replacement for the purple wire.

Click to expand...

OK, super! Got it. When I get back home later today I'll try out your suggestions. Thanks!

ILENGINE said:

there appears to be a 20 amp fuse in that wire. If that fuse(small chance) is blow or corroded(larger chance and possibly melted fuse holder) will cause the issues that you are having with the charging system.

This bypass wire is just replacing the purple wire in the diagram. If you get the temporary wire connected and it then charges then we know that the problem is in the purple wire. And you can go ahead and use your temporary wire as the direct replacement for the purple wire.

Click to expand...

Deafening applause for you! You are a Titan! It was in fact that 20 amp fuse -- blown to smithereens. Replaced it and my battery charges at 14v with everything wired back to factory settings.

When I ran that temporary wire that you suggested, the battery charged as it should. Then I knew to I had to find that 20 amp fuse you saw in the wiring diagram. It was well hidden or I would have checked it first. Your suggestions were stellar and you saved the day. Thank you a trillion times over!!!

ILENGINE said:

With the engine running full throttle connect the red lead to the B+ terminal of the regulator, and the black lead to the negative post of the battery. What is the voltage. Should read battery voltage. Now mow the red lead to the metal housing of the regulator while still keeping the black lead on the negative post what is the voltage. Any voltage over a about 1 volt indicated bad ground to the regulator and battery voltage would mean no regulator ground.

Just trying to make sure you are actually getting battery voltage to the regulator and not just creating a circuit that may not be there, and making sure the regulator is grounded.

Click to expand...

Score another win for yourself! I’d already tried two new regulators (1 Amazon, 1 OEM) and was getting -2v on the B+ to battery -.
This was first I saw about checking battery (neg) to regulator housing. Sure enough, it was showing 4v. Removed the bolt the regulator ground wire was under, cleaned them both up with some sandpaper and BOOM! Charging like a champ.
Thanks!
Jerry N

pict1000 said:

It was in fact that 20 amp fuse -- blown to smithereens. Replaced it and my battery charges at 14v with everything wired back to factory settings.

Click to expand...

Now, figure out WHY it happened. You are not done yet.

Everything has to be connected, and the voltage regulator body properly grounded. Measure output to the battery at the battery, not at the regulator output wire.

If it is not charging, then there is an open or corroded circuit between the regulator battery charge wire and the battery. An ignition switch or pin connection problem is fairly common.

What ILengine is saying in post 9 is :

It appears that the B+ post on the regulator terminal does not have a complete circuit to the B+ post on the battery.
When using the jumper wire you might consider installing a fuse of around 10-15 amps in the jumper wire.
Let us know what voltage measurements you get???????????
Sometimes this circuit is fused. Sometimes it goes through the ignition switch.
With a complete model number of your mower we might can find a wiring diagram?

Forest#2 said:

What ILengine is saying in post 9 is :

It appears that the B+ post on the regulator terminal does not have a complete circuit to the B+ post on the battery.
When using the jumper wire you might consider installing a fuse of around 10-15 amps in the jumper wire.
Let us know what voltage measurements you get???????????
Sometimes this circuit is fused. Sometimes it goes through the ignition switch.
With a complete model number of your mower we might can find a wiring diagram?

Click to expand...

The thread with the fuse issue was answered in 2019 and the wiring diagram for that issue was post 18. And the thread was brought back from the dead a few days ago with a repair of a regulator grounding issue from member @JNaughton using the testing that I posted in 2019.