Little FOCer V3.1 Motor Groaning

I recently the Little FOCer V3.1 but I cannot seem to simply run the motor without making a horrible groaning noise. Trying to run the motor right after motor calibration with the VESC tool yields a very apparent noise.
Please see video here:

I already tried changing the zero vector frequency up to 30kHz but the motor still makes the noises.

I could not hear any unusual motor sounds in the video but your L and Lq-Ld are very high for what a hypercore motor should detect at.

It has been hard to track down this issue because it is very intermittent. Eventually we were able to isolate the cause in a way that we are confident it happens when high voltages are applied without a power ramp up. So you are more likely to experience it on high voltage packs like 19s and 20s than a 14s or 15s. You can test this by specifying the motor detection to use less amps… IIRC, i think it defaults to 50amps but this is configurable in the wizard

We are working to test a fix that we can ship to you once we have tested it and its ready. So send an email to and we will get the fix to you as soon as its ready.

For now, i am assuming you are running vesc6.0 or 6.2, if you roll back to 5.3 firmware for the time being, it will probably not be a noticeable anymore. This is why we have continued to ship all of our little focers with dado’s v6 firmware and have not yet adopted 6.x. This is a hardware related issue but some software versions deal with it a lot better. We never noticed a problem until we started using 6+ firmware because 5.3 just behaved better [in relation to this issue.]


Note, that we were still shipping focers with v5.3 because originally we believed it to be a software related issue. But once we confirmed the problem is hardware related, i have set our inventory to zero while we validate the fix, then flash and fix all existing inventory before resuming shipping. We apologize for the delay. We will announce a voluntary recall where we ship a fix to anyone that is having this issue when upgrading to vesc 6


did not hear anything out of the ordinary. However if you don’t like the result, as brian said rolling back to 5.3 could help. Alternatively you could try motor config > FOC > Advanced > observer type = ortega original. on v6 firmware this default is changed to mxlemming lambda comp (iirc), hence rolling back to old firmware.

Hey Brian,
Thanks for the response.

I already sent an email to but have not received a response back. Also I was running V5.03 on the Little FOCer because I had the same issue on V6.0

Issue mitigated with a 100uF capacitor between 5V or 3.3V and GND.


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