Hub motor cuts out under any real load, no errors

[ezpz]

Hi all,

I have recently built an ebike using parts from a generic MTX rim 3000W hub motor conversion kit

72v30ah 20 cell battery with an 80A JBD BMS
Fardriver ND72260 Mini12
3000W Hub motor wheel 27.5 inch
Wrist throttle

It seems to run completely fine when you lift the rear wheel, perform auto-learn, give it full throttle. I can see it spins up to 900 odd RPM with no stuttering or juddering at all.

However under load, the motor cuts out at around 450RPM or 30-32mph. The motor will not be operable until I come to a full stop and the controller detects it. At which point it will let me use it as normal again.

There are no errors or faults in the Fardriver App (I screen recorded and checked every frame), BMS does not get tripped (I have dropped the line current and phase amp current to 40A and 180A which led to the same result), no errors on the BMS either.

The only thing I see is it going from MTPA to Weak on the graph page, which suggests a field weakening issue. I've changed the weak character and response to loads of different combinations and nothing seems to affect it.

Temperatures and amp draw looks completely fine, I've separated the hall sensor cables (even twisted them to reduce any potential EMF interference), triple checked the phase cables and nothing seems to make any difference.

Set the ratios to both 100 percent and 0 percent, no difference there.

Does anyone have any advice?

 

[Apartunis]

I suspect a generic Jung Kee 3kW controller with no bells or whistles would work without complaint. That is my experience anyway. If you want something with lots of knobs to twiddle then you must like messing with it. That appears to be what you are doing.

 

[ezpz]

I suspect a generic Jung Kee 3kW controller with no bells or whistles would work without complaint. That is my experience anyway. If you want something with lots of knobs to twiddle then you must like messing with it. That appears to be what you are doing.

I chose the Mini12 due to the form factor and the ability to adjust speed/power without a screen for a discreet build. Replacing the controller isn't much of a fix - I just want to understand what is causing it so that I can attempt to fix it.

 

[stancecoke]

The only thing I see is it going from MTPA to Weak on the graph page, which suggests a field weakening issue.

If you want to disable the weakening field , you can set "weak response" to "7-none"

 

[ezpz]

I've had a look at this page and the VOL counter goes up by 2 with each time it cuts out. However neither my onboard voltage display nor my fardriver reflects this