Problem programming VESC : Dual FOCBOX + 190KV 6355 TorqueBoards Motors + 12s4p battery

Hi everyone,

I have a problem with my (first) build : when I press the throttle on my remote, my motor makes a beep noize but it doesn’t turn.

Here is my build:

  • dual FOCBOX motor controller (split PPM, not master-slave through CAN)
  • dual 190KV 6355 TorqueBoards motors (belt drive, not HUB)
  • 12s4p battery

To configure the two focbox, I followed the enertion guide :

I left all default values like recommanded, and the sensor cables of the motors is plugged in. Something that I noticed : when I do the “start detection” on each motor, it spins fine, then brakes making the beep noise. Sometimes it looks like it struggles to brake. as a consequence the BEMF coupling detected if very high (around 1500-2000) whereas when it doesn’t struggle, it stands around 800 like the other motor.

My questions are:

  • is my motor broken?
  • what can be wrong with my motors and how can check that?
  • are default values good for my build ? or what should I change ? to what values ?
  • any suggestions ?

Thanks for the help

some additional information would be good.

  1. did you set up in BLDC or in FOC
  2. what´s the standard settings (as min I don´t remember them) screenshot would be nice.
  3. did you do motor detection with or without belts attached
  4. did you set your motors up in sensored or unsensored mode
  5. do you get any fault after motor detection.
  6. is your battery charged and did you set the battery cut off limit right
  7. is your remote charged

i think that´s all for now. maybe one of the points already will fix your problem.

1 Like

Did you remove one of the 5v pins?

Thanks for the reply. Here are some precisions:

  1. I use BLDC.
  2. It’s the one you get when you click “Read Default Configuration” (cf. screenshot)
  3. I tried both.
  4. I tried both (I actually don’t know wether I should use sensored or sensorless, the sensor cable of my motor is always plugged to the vesc btw).
  5. No fault after motor detection.
  6. Battery at 89%. I don’t know for the cut off limit… How to make sure I set it right ?
  7. Remote 100% charged.


You mean for the split PPM? No. Should I?

Try running it sensorless if your running sensor

Ok can you explain the difference really quick?

I’ve always had trouble with motors spinning sensor(don’t know if I’m doing something wrong) but I’m always getting good result sensorless. And if using ppm splitter you are suppose to cut one of the 5v off

That kinda makes sense for the 5v pin, but what can happen if I forgot that? (I actually forgot that)

Yes you should. Get the 5V only from one focbox. Take away the tick at limit max erpm with negativ torque please. That means if you reach full speed your focbox would make a full break. Something you don’t want! Try this both first. If it not work, try to set up in FOC sensored. Should be no problem with focboxes.

There can be a potential difference which means one focbox would try to compensate the other and fry your ppm input or as min disturbe your signal

Ok thanks for the information. I’ll try what you say right now. Should I try BLDC sensored or sensorless? Are all the default values ok?

First fix the 5V thing. Don’t change anything else. Try your luck and then continue one by one and look if one of the changes will help.

PS: the stock settings are ok for now if your pack is made out of Samsung 30q cells

Make please a screenshot of your battery cut off settings too.

I just tried with only one 5v pin and without the limit max erpm and I had the weird thing again: on the same motor,

  • one start motor detection looked fine and gave a BEMF coupling of 730
  • one looked weird with the motor struggling to brake and gave BEMF of 2000 What does it mean?

Battery cutt off start and end are on the screenshot (33 and 30 V)? is there other battery cutt off parameters?

They Already in your screen shot… My fault. Didn’t use bldc tool long time. The settings are for 10s. They too low for 12s. That will not fix your motor problem but please set it up to 3.3v per cell start and 3v per cell end. So 12x3.3 and 12x3

Ok thanks, should I also change the max and min input voltage too?

Motor detection should be done always without load, so no belt attached. It is like this at the moment? Can you spin the motor with your hand? Do you hear any grinding noise or one motor turns worse than the other?

No, let that. That’s fine

@Andy87 as youre active the thread right now, shouldnt the Limit ERPM with negative torque be unchecked?

Its likely not part of the problem OP but you dont want funky breaks at peak speeds