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[rogerpiano]

Hi everyone. I ask for help to identify a problem.

Model: S 2019 11kw, no charge tank, no power tank

KM: 5000 (never driven in the rain or on dirt roads)


For some days I have been hearing a disturbing noise when I release the accelerator and regeneration is activated.

I performed this test: I accelerate from 0 km / h to 30-40 km / h and leave the accelerator (tested in ECO, SPORT and CUSTOM mode with 0% neutral regeneration and 0% brake regeneration)

In the audio files that I attach you can clearly hear that in SPORT, as soon as I release the accelerator, a noise comes out that resembles a piece of paper placed in the spokes of a bicycle (the same happens in ECO mode)

In CUSTOM mode with 0% and 0% the noise disappears.

Other tests carried out:

- CUSTOM (100% neutral and 0% brakes): no visible regeneration and no noise
- CUSTOM (0% neutral and 100% brakes): noise present when brake and regeneration present during braking

I also noticed that in CUSTOM 0% and 0% mode the bike is quieter even in acceleration and seems smoother in gear, while in ECO and SPORT I feel a slight resistance in acceleration and also a certain noise.

Has anyone ever heard such a noise? It doesn't seem normal to me and I'm worried

[Kappi]

Hi Rogerpiano,

as you describe the noise only being present when regen is active: could it be that what you are hearing, as is present in your sound flie, the belt "ticking" while loging into the teeths of the front or rear sprocket with higher belt tension on the bottom side than on the top side (due to force form engine breaking)?

Best regards
Kappi

[TheRan]

To me it sounds like the normal regen noise combined with some rattling, the obvious thing to do would be to check every bolt you can find especially around the rear end.

- CUSTOM (100% neutral and 0% brakes): no visible regeneration and no noise

I could be wrong but I don't think coasting regen can be set higher than braking regen (even though the app is silly enough to let you do it), it always has to increase or stay they same when you get on the brakes so the braking regen is used as the max limit.

[Crissa]

On the S platform, at least mine, total regen seems to be Coasting+Braking.  Braking regen seems to be deducted from throttle position if used without releasing the throttle.

I can't hear anything.  Nothing as loud as plastic rattles or rotor wobble on my bike.

-Crissa

[ESokoloff]

What’s the tension on the belt?

[AutoE]

Lift the rear tire and listen carefully at low speed. Record and post here both when lifted and with load.

[rogerpiano]

Thanks everyone for the answers

The belt tension is around 40kg.

The noise, unfortunately, is more evident when listened to live, and it is clearly audible also by passersby. In a sense, it is acting as a noisy signaller of my passage, but I am certainly not happy about it. 

As an inexperienced I think it is connected to some mechanical part that is activated with regeneration, because any other hypothesis would mean that I should always listen to it.

By the way, I have the impression that I no longer notice the percentage increases in charge due to regeneration on the display, even if my post-lockdown use has been rather limited.
In my driving style I have always used the eco mode and I have limited the use of the brakes a lot to take advantage of the regeneration, practically before each slowdown even at high speeds.

Now I will try to take a few longer journeys to verify the extent of the regeneration, and to try to record the deceleration with the wheel raised.

In which part of the bike are the mechanical components that activate regeneration?

[Gains]

There are no mechanical components that activate the regeneration. If you sent electric energy to the motor, it turns. If you turn the motor it makes electric energy.
One could compare it with a propeller ,if it catch wind it turns ,if you make it turn, it will make wind.
The motor will need to be controlled  ,you want it to do what you ask from it via the throttle .
You can not just sent some electric energy to it ,and hope it will turn in the right sense and with the right speed and force ( torque ).
This is why there is a controller on your bike. It s a computer that calculates constantly what amperage and what frequence that needs to go to the motor ,to make it respond to the throttle inputs the way you like it.
Because everybody has a differend riding style zero gave us since 2014 a custom mode, so you can adapt the throttle response to your desires.
No mechanical components ,just a computer.

[rogerpiano]

There are no mechanical components that activate the regeneration.

I wrote "mechanical" because the noise seems to be generated by a moving part that rubs against the other, at a speed proportional to that of the bike
 
It really reminds me of when children mount a piece of paper near the bike wheel so that it bumps into the spokes to create noise

[Gains]

The belt and the wheel are the only moving parts, check if nothing can rub against the belt (like the fender) and check the tension and alingment of the belt.

[rogerpiano]

The belt and the wheel are the only moving parts

I wonder, however, what changes in the movement of the belt and rotates between

- the acceleration phase (no noise)
- deceleration without regeneration (no noise)
- deceleration with regeneration (noise)

[TheRan]

The difference between acceleration and deceleration (with regen) is that the upper and lower run of the belt is under tension respectively. On a chain driven bike with some slack I could imagine under regen the lower run becoming tight and possibly contacting something, but on a bike with a tight belt that won't be happening. Possibly the motor could be shifting if it's loose so give that a good push to make sure it's not moving, also try moving the rear wheel (left and right, obviously rotation around the axis of the axle is good) with the rear supported on a stand. Along with checking if any bolts are loose I think there are jam nuts on the adjusters for the motor position so check that those haven't worked loose.

[AutoE]

you might also be hearing bad bearings.

[Crissa]

Yeah, there's not mechanical parts that move when in regeneration...

...But the tension and vibration do change.  So it could just be something loose rattling in the plastics, bearings, or the motor mounts.  They're all in spec, right?

-Crissa

[KuRi]

Exactly same "noise" here. Started at summer, once ambient temp were 30ºC+

The sound is not only present with regen, I am pretty sure if you listen carefully you will listen to it while using the throttle just to keep a constant low speed (30-40km/h).

I just opened a thread with the same "problem" some days ago, and my audio file is very similar to yours (please check it).

It is totally normal and it is the teeth of the belt agains the front sprocket when some tension is achieved (regen, slow speed, ...) and it depends a little on the tension of the belt. If you loosen it a little it will sound less, but be aware not to go below the minimum 25kg of recommended tension (just what kappi said)