My Kingsong 18XL has rattling noise when decelerate to stop?

[JimJJ]

Hi i have a question about my new Kingsong 18XL since it made a rattling noise when i decelerated to stop. Sometimes, the noise occurred while riding it at low speed after riding for a while. It sounds like pouring cereal into empty bowl XD. 

 

I dont know how to upload video but my wheel sounds exactly same i know that high pitch sound is normal but how about rattling sound? In this video at 12:47 minutes you can hear it when he decelerated and stop and also you can slightly hear it from 10:08 minutes when he was riding. 

 

i just wanna check if it is normal since when i looked at others video it didnt make this sound or maybe i didnt hear other videos well. 

Do you think this is normal? Since i have inmotion V10 and it doesnot make noise. I am sorry if i am being too paranoid lol

 

[JimJJ]

[Circuitmage]

It's a little hard to hear, but is it the clicking sound when decelerating?

My best guess is that you are changing the angle of weight distribution just enough to cause something on the tire to slightly rub during slow down. Since it's a clicking sound, it may just be one small thing on the tire. The clearances between the tire and the shell usually are not that great, so maybe it's just on one side or front or back...like a 5mm piece of rubber flashing sticking off the tire (??).

On my 18L I ran for a few days with a slight wobble, until I realized I mounted my tire offset by about 7mm on one side. That was enough to cause a noticeable wobble, but that is a different thing than you are pointing out. The only reason I bring it up is that any small difference can cause an issue, and I have noticed my 18" tire mounts much looser than my 16S tire did.

It could be something on the shell rubbing up, or your valve stem.

I've also had leaves caught in my wheel that make more sounds depending on how I shift my weight.

If you've checked the tire for proper mounting, rotation, debris, balance, etc....it still could be something in the axle or motor. However from your videos it appears to ride OK.

 

[JimJJ]

9 hours ago, Circuitmage said:

It's a little hard to hear, but is it the clicking sound when decelerating?

My best guess is that you are changing the angle of weight distribution just enough to cause something on the tire to slightly rub during slow down. Since it's a clicking sound, it may just be one small thing on the tire. The clearances between the tire and the shell usually are not that great, so maybe it's just on one side or front or back...like a 5mm piece of rubber flashing sticking off the tire (??).

On my 18L I ran for a few days with a slight wobble, until I realized I mounted my tire offset by about 7mm on one side. That was enough to cause a noticeable wobble, but that is a different thing than you are pointing out. The only reason I bring it up is that any small difference can cause an issue, and I have noticed my 18" tire mounts much looser than my 16S tire did.

It could be something on the shell rubbing up, or your valve stem.

I've also had leaves caught in my wheel that make more sounds depending on how I shift my weight.

If you've checked the tire for proper mounting, rotation, debris, balance, etc....it still could be something in the axle or motor. However from your videos it appears to ride OK.

 

This is not my video but my wheel made same noise as him. You can hear slightly clicking sound from 10:08 also if you use headphone, i a little louder in real life

[Circuitmage]

I have been riding my 18L , even though I vaguely recall a few instances of hearing what almost sounds like a griding sound when I come to a stop. It doesn't seem to happen all the time, so kinda strange. Not sure if it's related to this clicking sound or not, but seems likely.

 

[Joker10]

 My 18l does make a little noise when hard braking.  Not sure if it’s the same as in the video though because the camera is off to the side, and my head it right above the wheel.  Sounds similar though.  My 16s made some noise under hard braking as well.  

[Meserias]

try to image how much current it's necessary to brake hardly.... many things happen there.
very high intensity current it's normal that sound in my opinion

[Circuitmage]

So, what is that meaning to say? That the high current is arcing across with wheel when decelerating?

Or that some components in the wheel or on the motherboard are making that sound?

I would be concerned if any high current condition is inducing a sound effect.

 

[Chriull]

1 hour ago, Circuitmage said:

So, what is that meaning to say? That the high current is arcing across with wheel when decelerating?

Or that some components in the wheel or on the motherboard are making that sound?

Most probably its some current/voltage limiting which "produces" this "low frequency" pwm that makes this rattling sound.

Was also reported with some earlier GWs (?MCM4, ACM?) which made such rattling sounds at strong accelerations from low speeds - there the current limiting produced this (GW statement)

Quote

I would be concerned if any high current condition is inducing a sound effect.

High currents produce strong magnetic fields which create a force on the wires. So "loose/not fixed enough" wires could move and produce sounds.

I would be very concerned too if this would be a reason for such loud sounds from an EUC.

Ps.:

It's the motor making this sound (by the torque ripples) caused by the pwm, introduced by the limiting.

Like the high frequency pitch while "normal" driving caused by the high frequency pwm.

Maybe you have heard the beeping/music played from drone bldc motors. Could be made like this with an EUC, too.

Edited September 23, 2019 by Chriull

[Mike Sacristan]

Old thread I know... was there ever any resolution?
It is hard to tell from the sound if it is cogging...

I recently started getting the same thing with my 16X. A rattling sound. I think it's the handle! If I extend the handle a bit and hold it while riding I can't make the sound.
It happens especially when doing heavy acceleration and braking. Sometimes it will rattle more sometimes less.

[null]

Speaking of noise.

I have a sort of vibration from the wheel (mainly on the 18XL) when accelerating / breaking (magnets pull) but no more over a certain speed. My theory is that coils are being pulled towards the magnets, eventually (hopefully only the tie wrap) rubbing on the shell. At speed the inertia might be enough to pull it even further / away from the rubbing area.

I should open the motor to check but haven’t had the occasion / courage yet.

Edited November 18, 2019 by null

[Mike Sacristan]

47 minutes ago, null said:

Speaking of noise.

I have a sort of vibration from the wheel (mainly on the 18XL) when accelerating / breaking (magnets pull) but no more over a certain speed. My theory is that coils are being pulled towards the magnets, eventually (hopefully only the tie wrap) rubbing on the shell. At speed the inertia might be enough to pull it even further / away from the rubbing area.

I should open the motor to check but haven’t had the occasion / courage yet.

Isn't this just standard cogging? What happens if you brake down a hill or climb slowly up a steep one?
My MSX is quite loud in these scenarios. Magnets!
How do magnets work?

[null]

Yes, how do they work. It can’t be explained

The vibration seem more linked to pull (ie yes up a slope, will have to test a bit more, not so many of those here) or hard breaking.

Ill take anything standard over rubbing coils, would be glad for that It’s just no one ever mentions vibration but only noise. The later doesn’t matter much, vibrations feel wrong. Maybe I’m just being the princess on the pea.

 Looked up cogging, it could be that, will look closer at whether there could be a reason to disappear (quite abruptly) at high speed.

Side observation: when slaloming / carving it is stronger at the center, lesser in the sides.

Edited November 18, 2019 by null

[Aneta]

3 hours ago, null said:

Speaking of noise.

I have a sort of vibration from the wheel (mainly on the 18XL) when accelerating / breaking (magnets pull) but no more over a certain speed. My theory is that coils are being pulled towards the magnets, eventually (hopefully only the tie wrap) rubbing on the shell. At speed the inertia might be enough to pull it even further / away from the rubbing area.

I should open the motor to check but haven’t had the occasion / courage yet.

In BLDC motors, coils don't rotate with the wheel, they are completely stationary (they are wound on the stator). It's the magnets that move (they're glued to the inside of the rim). So, it's impossible for centripetal force to affect coils at all. If the magnets got unglued, that could explain the noise and its disappearance at speed. Another possibility is that motor covers got loose. It's the motor covers attached to the rim with measely M4 screws that transmit the weight of the rider from axle to the road, that's a lot of stress.

 

[null]

11 hours ago, Aneta said:

In BLDC motors, coils don't rotate with the wheel, they are completely stationary (they are wound on the stator). It's the magnets that move (they're glued to the inside of the rim). So, it's impossible for centripetal force to affect coils at all. If the magnets got unglued, that could explain the noise and its disappearance at speed.

Another possibility is that motor covers got loose. It's the motor covers attached to the rim with measely M4 screws that transmit the weight of the rider from axle to the road, that's a lot of stress.

 

Thanks, good observation about the coils / stator being em, static. I knew but hadn’t thought of it. Then it might indeed point to the magnets, where “disappearance” at high speed stay valid.

Ill open it some day I gather the courage (and maybe some new ball bearings). Can check the cover at the same time. Posting back here.