Is my controller or throttle bad?

[Mork]

I have a Pro 902 setup that all of a sudden stopped working.   Ive dug through all the articles on here I could find about troubleshooting and this is what Ive come up with.

I think the wheel/hub is good.  I did the following tests:

https://goldenmotor.com/SMF/index.php?topic=6508.0
I did the hall sensor test and found the voltage to fluctuate between the 0 and~5V as I slowly turned the wheel for each lead.  So that seems good.

https://www.goldenmotor.ca/FAQ/questions.php?questionid=94
https://goldenmotor.com/SMF/index.php?topic=4140.msg24014
I shorted out the phase wires, and noted a resistance with each pair when I then attempted to rotate.  So that also seems right

Now for the controller/throttle:
https://goldenmotor.com/SMF/index.php?topic=7067.msg38415#msg38415
I measured the voltage between Z/0V and T1/5V and its showing 5V. (That’s good)
I measured the voltage between Z/0V and T2 and it reads 0.8V (also good)

But here’s where I think I’ve found a problem.  According to the earlier post (https://goldenmotor.com/SMF/index.php?topic=4140.msg24014) if I measure between T1 and T2 I get 4.2V with the throttle released and 0.8 when full throttle - this seems to be the exact opposite of what I should be getting?

Can anyone confirm if this is a faulty controller/throttle?   Or perhaps suggest next steps?

Thank you

[Bikemad]

Hi Mork andto the forum.

Unfortunately, it looks like you may have a faulty controller, as the throttle appears to be working correctly.
If you measure the voltage between between the Z/0V and the T2 terminals, you should see it go from ~0.8V when released to ~4.2V at full throttle as expected. 

As you have already checked the Hall sensors, Phase wires, and the throttle, the only other likely causes will be battery/BMS or a fault in a brake switch or wiring

Unplugging the brake switches should rule out the possibility of the problem being caused by a short circuit in one of the two brake switches or their combined wiring.
If the motor works with the brakes unplugged, the problem will be somewhere in the brake wiring or one of the switches.
If the motor still doesn't run with the brakes unplugged, it could well be a failed controller.

Check the battery voltage across the B+ and B- terminals at the controller to make sure you have at least 24V, 36V or 48V (dependant upon your nominal battery voltage).

If you shorted out the phase wires at the controller terminals during your previous tests, we can assume that the three Phase wires (and any additional connectors if fitted) between the stator windings and the controller are all OK.

The same goes for the Hall sensors, assuming the voltages were checked at the rear of the 5 pin controller connector.

If you can't find anything obvious with the battery/bms or brake switches/wiring, I suspect that a replacement controller will be required. 

Alan
 

[Mork]

Hello Alan,
thank you for your response.

I should have mentioned that I completed all these tests with the brakes and horn/cruise connections disconnected.

I can confirm that when I measure between Z/0V and the T2 terminals, I get the 0.8V released and then 4.2V at full throttle.   

I can also confirm 24V (25.5V) at the B+ and B- terminals, and the Hall sensor testing was done at the rear of the 5 pin connector.

Can you confirm if the measurement that I noticed between T1 and T2, where I get 4.2V with the throttle released and 0.8 when full throttle, is that wrong?  The one link I referenced seemed to indicate that the measurements should be opposite to that. (IOW  it should be 0.8V with throttle released and 4.2V with full throttle)

I should also add that this unit was originally purchased and used for a couple months using a 24V battery.  I was told that this motor would work fine with 36V, so I switched to a 36V battery which then ran fine for several months.   But I did notice yesterday while doing the troubleshooting, that on the throttle itself it indicates "24V" on the underside.   Perhaps the 36V was not acceptable?

thank you

[Bikemad]

Can you confirm if the measurement that I noticed between T1 and T2, where I get 4.2V with the throttle released and 0.8 when full throttle, is that wrong?  The one link I referenced seemed to indicate that the measurements should be opposite to that. (IOW  it should be 0.8V with throttle released and 4.2V with full throttle)

The measurement you observed is exactly what I would expect to see if I were to measure across T1 and T2, but this is not the correct way to measure the throttle signal voltage.

The throttle signal voltage (T2) should be measured relative to battery negative (The Z/0V terminal) not in relation to the +5V supply (T1).

Using a voltmeter set to the appropriate voltage range, place the negative (Black) probe on the "Z/0V" terminal and then use the red probe to:

• check you have full battery voltage on Connection "G" (Red wire) or the controller will not operate.
• check you have 4~5V on the "T1/5V" terminal (Red wire)
• check the throttle control operation by measuring the voltage on the "T2" terminal (Throttle signal wire). The voltage should be ~0.8V with the throttle released, and should rise to at least 3.25V at full throttle.

You wouldn't obtain the correct battery voltage by measuring between the +5v and B+, as the reading would be 5V lower than the actual battery voltage when correctly measured between B- and B+.
The 4.2V you observed with the throttle release is simply the difference between the 0.8V signal voltage (T2) and the +5V supply (T1). (5V - 0.8V = 4.2V)

I should also add that this unit was originally purchased and used for a couple months using a 24V battery.  I was told that this motor would work fine with 36V, so I switched to a 36V battery which then ran fine for several months.   But I did notice yesterday while doing the troubleshooting, that on the throttle itself it indicates "24V" on the underside.   Perhaps the 36V was not acceptable?

The voltage rating of the throttle unit only relates to the LED battery gauge and would not affect that actual throttle function.
The throttle will still function correctly even though the Battery gauge LEDs will not.
Check out this thread for more details.

It is definitely not a throttle problem, as your initial testing has already confirmed that the throttle is working correctly. 

Alan
 

[Mork]

“Using a voltmeter set to the appropriate voltage range, place the negative (Black) probe on the "Z/0V" terminal and then use the red probe to:
check you have full battery voltage on Connection "G" (Red wire) or the controller will not operate.
check you have 4~5V on the "T1/5V" terminal (Red wire)
check the throttle control operation by measuring the voltage on the "T2" terminal (Throttle signal wire). The voltage should be ~0.8V with the throttle released, and should rise to at least 3.25V at full throttle.“

- double checked all these, and they all check out good.

Hmmm.   I’m not sure what’s going on here then.  It would seem that the controller is interpreting and sending out the right signals? 

One other measurement I took, was from the ground (B-) to each of the three motor wires and it showed 25.5V for each one.  I don’t know if this is right?

[Bikemad]

Hmmm.   I’m not sure what’s going on here then.  It would seem that the controller is interpreting and sending out the right signals?

Hi Mork,

The short answer is, your controller is bad. 

The controller is clearly receiving the correct throttle signals from the throttle unit, but it is unable to send the requested power the motor because something inside the controller has failed.

One other measurement I took, was from the ground (B-) to each of the three motor wires and it showed 25.5V for each one.  I don’t know if this is right?

I would expect to see a reading of ~0V between each of the three phase wire terminals and Battery -, so it sounds like one of the three MOSFETs on the High voltage side has probably failed in a closed (short circuit) state.

If you unplug the three Phase wires and check the voltage on each of the controller's Phase terminals, I suspect it will only be one MOSFET that has failed (i.e. one terminal will read full battery voltage and the other two terminals will read the expected ~0V).

A closed MOSFET would basically pass full battery voltage directly to its corresponding Phase terminal, and the high voltage reading observed on the other two Phase terminals is due to the voltage passing through the stator windings and returning back to the controller along the other two Phase wires.



The above diagram shows a very basic MOSFET power circuit, which will hopefully allow you to visualise what I've tried to explain.



Alan
 

[Mork]

You were right. 
They were all showing 25V when plugged in.  When I unplugged them, just the green terminal read 25v and the other two are 0v.

A new controller it is then. 

Just so I understand, the 902 wheel will work at multiple voltages?   It’s the controller that needs to be programmed for the correct input voltage?

Thanks!

[Bikemad]

Hi Mork,

The motor will run on 24V, 36V or 48V, and the controller can be set to any one of these voltages using the USB programming lead and appropriate software.

I'm not sure if GM's more recent external controllers have changed, but the earlier ones would work fine on any of the three voltage batteries without having to change the controller's voltage setting.
48V batteries were often used with the controllers deliberately set to the 24V setting as some owners were convinced that the motor delivered more torque with it set that way.

Alan
 

[Mork]

Hello again,

Seems like the official at GM is it is a 24 or 36V motor only?   (https://www.goldenmotor.ca/FAQ/questions.php?questionid=35).  Some of these FAQ’s seem like they may be many years old though. 

Limiting the amps (https://www.goldenmotor.ca/FAQ/questions.php?questionid=26) to 10 amps running, 20 amps peek seems to be the recommendation.  I’d think with the amps limited, 48v should be acceptable?  I don’t see any more information about anyone trying 48V on their 902.    Maybe ill be the first.

Ive received the new controller and have installed it and basic testing looks good.   But I haven’t really been able to road test it yet since these are 4 large 12V lead acid batteries from another application.  Waiting for the arrival of my new 48V LIon battery