Motor Detection Failed, but motor is spinning

Hi everyone,

This is my first time posting on this forum, but I’ve been reading posts for a while. I’m setting up the VESC for the first time and I keep getting the error “Bad detection result received” when I try to detect the motor. When I hit “start detection” the motor spins up to 24,000 ERPM stops accelerating and then jumps up to 45,000 ERPM momentarily before cutting off.

The motor spins fine using the arrow keys, however I cant get it to detect. I have tried varying the Current and Min ERPM to no avail (300-1200 ERPM & 1-6A current). The motor always spins fine but wont detect. I have also tried varying the Battery cutoff voltages and changing to a much shorter USB cable. There are currently no faults when I check the terminal

Here are my current settings

I am using a TORQUEBOARDS VESC 4.12 Turnigy SK3 5055 430Kv motor (max 70A) 4X2S 8000maH batteries in series (8S, 29.6V 30C continuous)

I’m not sure if the high kV of my motor is causing the problem? If you have any suggestions I would really appreciate it.



just spitballing here, are your batteries fully charged ?

you’ve done most of what i’d do. I’d double check you have the belt/wheel disconnected if it might be part of the issue. I had one not detect when my belt was too tight, removed belt and detected fine.

Also, might here might be some usefull information …

Detection current is a bit low, try 6A

EDIT: nevermind i see you’ve done that

No my batteries are at ~50%. Ill try charging them

There’s nothing on my motor shaft. It’s completely free

ah it’s your max erpm limit. Your hitting almost 90k erpm during detection but your limit is set to 60k. You need a new motor…

Why does he need a new one if he is almost hitting 90k erpm? Can it fry the VESC?

Can’t I limit the max ERPM from the BLDC ? I have it set to 60,000 right now.

While he can raise the limit the drv is known to fry at over 60k. I wouldn’t risk it personally, even for detection.

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I thought the max erpm being at 60,000 despite having a higher kv would keep his motor from going too fast to damage the vesc and all would be good. ?

for me when it wont detect it’s either a short in the motor or magnets or rotor is imbalanced. does it spin smoothly or with any wobble?

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Detection is likely different, even with the normal limit i believe the vesc just shuts off or errors out when it hits

@Hummmie the motor spins very smoothly. I’m pretty sure I’m not shorting the motor leads as I soldered them and used heat shrink. There is no exposed wire.

@Jinra Could I detect the motor using less cells (6s) and then use those setting with the full 8s setup?

you need a new motor, you’ll blow out the vesc for sure when you use it

are you saying that because it’s so high kv? wont the erpm limit keep him under the limit and all will be well? maybe if he just uses fewer cells for the test if it’s a test specific thing?

I can’t say for sure since i haven’t tried it personally, but i believe the vesc turns off if it hits the limit. Besides that, it’s a very inefficient setup with huge losses.

so hitting the limit would cause a shutdown as apposed to holding the motor to a max erpm that it could run at? oo. but why do you say his set-up is inefficient?

I believe I can use soft limits on the controller side though. I chose such a high rpm combination because I wanted very high torque for climbing hills. From my calculations I should be able to do a 25% grade hill at 20 mph

you usually want lower kv motors for more torque not higher