Motors jerks at 14 mph with sine wave controllers

harrys

Pedelecer
Dec 1, 2016
215
31
70
Chicago, USA
I tried this with two different motors. Both jerk around 15 mph under throttle, the speed drops to 13. From there, it will accelerate again and not do another further jerking unless I stop it and restart.

It seems to be associated with both my KT 20A and 25A sine wave controllers. It doesn't jerk with a KT square wave controller. It does not jerk with a a simple no display controller I have. The jerk happens on two different geared motors.

I'm wondering if it's the display. It's a new LCD3 I bought last summer, but never used. until today. These controllers have been used before and never had this issue.

 
Last edited:

danielrlee

Esteemed Pedelecer
May 27, 2012
1,312
668
Westbury, Wiltshire
torquetech.co.uk
Hi

Before doing anything else, you should reset your LCD display to factory default by setting custom parameter C10 to 'Y'. Check to see if this solves your problem before moving on.

Weird motor behaviour is often caused by an incorrectly specified value for custom parameter 'C2'. You should try making incremental changes to this setting, starting at '0', each time increasing the value by 1 and seeing the effect this has on motor operation.

Dan
 

harrys

Pedelecer
Dec 1, 2016
215
31
70
Chicago, USA
Thanks daniel. I had done the reset.

After some more testing of my various ebikes I conclude that all my sine wave controllers do it. Slowly raising the throttle past some intermediate speed causes a blip where the motor noise changes. On my video, wiith only a bare motor, you see a speed drop. WHen a wheel/tire is attached, inertia maintains the speed. I tried it out in the shed with my ebikes, wheels in the air. At most, I'll hear a change in the pitch of the motor when it happens. No clunk. On the fat tire bike, there's so much noise, I can't even hear the pitch change. Anyway, it doesn't affect riding. I will not be worrying about it.