From Unofficial Zero Manual
The motor on 2013+ models makes a white noise sound at very slow speeds when rotated (by the wheels or shaft).
- This is also described as a "whirring sound".
- This is alluded to by the term "cogging".
- This is normal as long as it sounds like white noise and occurs as described below.
- Video Guide
- Strange noise Zero DS 2017 provides a reference for comparison:
- Related Confirming Symptoms
- The noise should only occur while the motor is rotated by external input (pushing the bike around or rotating the shaft).
- The noise should not while under power (when the motor is driving its own rotation).
- The bike should gently resist being pushed while the noise is audible.
- The direct cause is the controller applying a white noise field to the motor at very slow speeds.
- At least one connected battery's contactor must have been engaged for this to occur.
- This can occur while keyed on, or while charging.
- There are no detrimental effects, when the sound occurs by design.
- The purpose is for the controller to detect and maintain precise knowledge of the motor's rotor angle.
- This ensures that, if the throttle demands operation, the controller will apply the field correctly to the rotor.
- You may infer that at least one contactor is engaged to power the controller.
- If the bike is keyed on, you may infer that the motorcycle should be ready to drive.