Motor HOT, motor or Controller issue?

[rockfordpi]

About 2 months ago, I put a 420 amp Navitas TSX 2.0 controller with OTF module on a friend's G29. Stock controller was definitely bad. Could have been my imagination, but the cart seemed a little slow even with OTF turned all the way up.

Now the solenoid has failed. I benched checked it and it still clicks, but no continuity. Obviously contacts are burned up. Initially it was clicking on the cart, even after contacts failed. At the end, I think (not 100% sure) it even it stopped clicking all together.

Installed a new SW180 solenoid. New solenoid does not click. Has proper voltage on control wire input. Obviously no ground. When I jumper over from solenoid direct to ground, solenoid clicks.

I was leaning to controller failure, then I happened to notice a tiny amount of smoke coming up from motor. After only a brief time, motor was hot, not so hot I could not touch, but could only touch it about 2 seconds before it burned me. Accelerator was never pressed after I got the solenoid click.

I think this explains why the original solenoid contacts were burned up. I am wondering if this could have also gotten the original controller? Or, has the new controller simply failed and is applying the wrong or partial voltage to the motor?

Does not seem like it could be the motor since there should not have been any current applied to the motor before the accelerator was pushed?

All suggestions, ideas and comments are appreciated.

[Golf cart guy]

On any controller failure, a cause should always be looked for other than just saying the controller failed. This being a Yamaha, a shorted or damaged motor should always be suspect. I think this is why so many have issues with rebuild controllers failing.

Check everything out at this point to make sure you don't have a major short.

[rockfordpi]

Originally Posted by Golf cart guy

On any controller failure, a cause should always be looked for other than just saying the controller failed. This being a Yamaha, a shorted or damaged motor should always be suspect. I think this is why so many have issues with rebuild controllers failing.

Check everything out at this point to make sure you don't have a major short.

Just to be clear, when the solenoid closes there should be some power from the controller to the motor even before the accelerator is pressed?

[Golf cart guy]

power to the motor would try and make the cart run.

Does reverse buzzer work? Controller controls that, so bad controller many times youll have no reverse buzzer either.

[rockfordpi]

Originally Posted by Golf cart guy

power to the motor would try and make the cart run.

Does reverse buzzer work? Controller controls that, so bad controller many times youll have no reverse buzzer either.

Buzzer does not work, but it may have been broken before.

Back to my original confusion about your first answer. I understand that power to the motor is what makes the cart run, my question is should there be power to the motor BEFORE the accelerator is pressed as is happening per above?

[cgtech]

There should be B- at the motor, but not B+.

[rockfordpi]

Originally Posted by cgtech

There should be B- at the motor, but not B+.

With the Navitas controller, I think it is changed to where B+ is always at the motor (you cut the Y cable and move to B+ controller terminal when you put in Navitas controller) when solenoid is engaged.

I think the Navitas Controller then closes the loop back to B-. So, either some way the motor is somehow shorted to B- and heats up when solenoid is closed, or the controller is providing a closed circuit back to B-.

It seems l like if the controller were proving that circuit back to B-, then the overload would kick out before the motor started smoking.

So, now I am leaning back to a motor issue, but I am still perplexed. It seems like this would need TWO shorts for it to cause the motor to get hot.

[cgtech]

Aha! Never used a Navitas, so thanks for the info.

[rockfordpi]

Originally Posted by cgtech

Aha! Never used a Navitas, so thanks for the info.

Ok, got it narrowed down. When I remove EITHER or BOTH F1 and F2 from the controller, turning the key on makes the solenoid engage and reverse buzzer beep.

When BOTH F1 and F2 are connected, solenoid does not close, buzzer does not beep. I am guessing controller is sensing a problem in the field coil and shutting down.

1 ohm resistance between f1 and f2.

This seems like it has to be a motor issue. Any chance it could be just the brushes or is it time to throw in the towel and buy another motor?

[cgtech]

On a sepex cart, the field circuit does not touch the brushes (it better not, or bye bye Controller). And 1 ohm is not necessarily a bad field reading. Most ohm meters are not too accurate in the 1 ohm area and below. I would expect something around 1.5 ohm, but like I said about the typical inaccuracies in "low ohm" readings.