Any advice for low RPM jitter on 6374/190kv?

Hello all! new to the group here. I am looking for some help with sorting out my new DIY.

The Issue: at low RPM load or no load there is some jitter from both of my motors. this also produces a tic sound as it does so.

There is nothing physically touching/hitting within the motors. watching real time data from BT looks to have very fast current spikes for each of the tic sounds.

Current parts are all new:

LandYachtz Evo 36 deck

Flipsky DKP trucks

Riptide Bushings kit

Flipsky dual 6.6 plus FW 5.2

Flipsky dual 6374/190Kv battle hardened

Flipsky VX2 UART remote

Flipsky BT module

Cloud 120mm wheels

Gearing is 15T/40T

Battery is 10S4P Samsung 30Q cells with BMS discharge bypass

  • I am currently still awaiting my enclosure from Eboards.Peru

Below are pics of my current VESC settings

Kind of sounds like belts might be too tight?

When pressing the belts I get about 3-4mm of deflection, but I will attempt to loosen them a little and see what happens. I will also test with no belt.

Could also be the motor pulley shifting on the motor shaft?

Maybe drop some thread locker onto the shaft before installing the pulley.

It is not physically contacting or shifting anything. I have thread loc on the shaft as well as all screws that are not a ny-loc type.

I just tested with wheels and belts removed, same issue.

Does not have the issue when running motor detection or testing motor direction

I believe it to be a setting that I am missing but just don’t know what.

Did you go for a ride on it yet? would be good to know if there is any other issues to help with diagnosis.

Yes I have taken it on a test ride. at first my motor settings initially were set to 75A/-60A and under full throttle and heavy load (in grass or take off full speed from a dig) it would shut off for 3 seconds (which sent me flying forward). I turned my motor amps down to 60A even though specs state 85A and motor detection finds them at 79A. This would only happen when in High mode. The noise is more apparent when using revers since its easier to maintain a very low speed even without load (smart reverse is set to 7%)

No cutout issues since turning down the motor amps. Other than the noise which you kind of feel as a tap when it happens

these are the results from testing with belts and wheels off and inspecting the motors …

It kind of sounds like a mech thing, so probably a bad bearing. Send video to Flipsky. Does the noise follow the motor if you swap ESC wiring around?

My guess is this is probably unrelated, Seems the ESC doesn’t like the full current/load, can check if there are some errors in the vesc tool. There is a way to reduce the error timeout length so it’s less/not noticeable… can’t remember the exact setting name.

I will contact Flipsky. I have been at this for about a week but this is also my first full DIY so I am no expert… yet. For the noise, its seems to me like a timing or current issue from what I gather. It will tap like this even without motor rotation if there is heavy load. If you look closely at the first video I posted in this thread at about 0:42 you can see once I get on that the noise/jitter is occurring as the motor tries to start up slowly with my on it (6ft/200lbs) on the carpet.

Is it coming from one motor or both? Does the fault follow the motor?

Sometimes when a VESC goes from sensor mode to non-sensor mode you might get a noise or little glitch etc, but that is normally at slightly higher RPM than what you are showing in videos. However, you can try changing the ERPM at which VESC switches from sensor to sensor less. Try a little bit higher at 3000

Some people play around with switching freq in attempts to modify the noises made, but I doubt that is required here.

my sensorless ERPM is higher than that. I can check shortly. I think it was closer to 3k. switching frequency i will have to check. I did not modify anything there from what default was.

My switching frequency was 25khz and my sensor less erpm was 4000. I set it to 2000 and sitting in the air it was nice smooth startup. Using my hand to add some load and the motors felt smooth and sounded great! When using the smart reverse the issue was still present, but this is a huge step forward!

I got a chance to ride it this morning. The jitter is much better with erpm set to 2000 but it is still present. This makes me suspect some setting with the hall sensors. Hall sensor detection has no faults.

Is it possible to switch FOC to sensorles and does that cause any problems?

Any other possibilities anyone can think of?

Anyone have a good link to details or real world effects of some of these more uncommon settings? (Like switching frequency)

I heard it happen every rotation. Is it both motors? I think there is a drop in theorizing the pulse of foc. First thing is, dismantle your three wires, and guarantee the solder is good. Then, when reassembling, insulate the three from each other a bit. Then, check at what rpm the hybrid mode switches to foc from bldc.