King Song S22 motor stator slippage issue: more severe than expected

[supercurio]

Quote

It didn’t happen right after opening but soon after it started having problems with the motor. A very weird rubbing noise from inside the hub. The tech support said they’ve never heard it before. Then one day I was riding it and the rubbing suddenly got really bad, really loud. Then it cuts out a couple seconds after while just making that sound.

Quote

The scraping sound happened at one point pretty quiet and subtle. then I rode it for 25 miles that day and just pushed the crap out of it. Then I noticed that it went away for a week or so then came back with a vengeance lol

The temperature did come off at one point then I put it back on after getting pic of where it is.

I never really let it fall over or crashed it for the most part. Nothing that I would say that is serious.

I did fall and got hurt pretty good. Both my forearms, big circle on my palm, big circle on the shoulder,knee,butt, knuckles on one hand, and the tip of a single finger. I was sore all over and had a couple bruises of course. Thankfully I had a back back on or my back would also be turn up. The back bag got torn up thankfully.

That happened on AUG 2 and thankfully I’m just bout fully recovered from it now.

Source: reddit thread

This changed my opinion on the severity of this issue and how it should be addressed.
Noticing a faint scraping sound which disappear quickly, and reacting within 2s to another sound before cutting out is not something that can be expected from any rider.

With an expected failure rate between 5 and 15%, that's a lot of crashes and a lot more people getting injured.

Although the test is not confirmed nor official yet, I would now recommend every owner to complete the stress test on their wheel before riding it, especially new owners: first thing out of the box.
Either that, or recall.

[oolong]

1 hour ago, supercurio said:

@Planemo important to note that the issue can occur without the aggressive riding, jumping an experienced rider would do, or running the stress test.

One of the case is a new rider who learned to ride on the S22 as first wheel.
It would be comforting to think it can only happens if you push the wheel really hard, but it doesn't seem to be the case.

It would be far more comforting to me to have something that would fail early and easily (especially with a stress test) than thinking everything is fine and then suddenly failing 6 months later when riding hard one day.

[0000]

Probably better discussed in a separate thread, but reading this I'm wondering if any of these manufacturers will ever invest in expanding a physical presence in our Western markets.

Even if it's just liaison employees in lieu of physical infrastructure and manufacturing capability, it would help in situations like this, especially for coordination of problem resolution and customer loyalty. Just having official feedback loops directly to the manufacturer for potential design changes and improvements would be nice. It seems like the revenue generation could be there to justify this kind of expense as these wheels have to be fairly high margin products particularly as prices have inflated a noticeable amount in the last couple years.

I was thinking about this in another thread yesterday, and I got curious about the vendor-manufacturer relationships. Not just speaking about the S22, but in general, I wonder how close are vendors getting to dropping product lines if the status quo doesn't improve? Vendors covering recall expenses can't be profitable, not to mention logistical expenses, not to mention the personal headaches and time involved in fielding customer expectations under these circumstances.

Edited September 2, 2022 by Vanturion

[Funky]

And that's why i don't buy any "new" wheel - which have not been tested at least a year beforehand, by other riders.. (Better 2 years.) I'm so happy that i bought my 18xl last year. (As it have been tested truly by other riders for many years.) 18xl have gotten many updates: More powerful motor, better inner shell, better lift sensor, better trolly handle, bigger pedals..

This just shows again and again - you don't want to buy any just released wheel. As most of them are shit anyways. First few batches are always duds.. (In my eyes S20/22 all of them are duds, till they rebuild the suspension.)

[Tawpie]

I've been running a background task trying to figure out a telltale to indicate that your motor is slipping, preferably without having to remove the motor cover. I'm guessing you might have to remove the cover at least once, at the very least you'll need to get access to the hall sensor output.

Obviously, opening the cover and marking the stator position on the rim is a solution, but you must be able to see it and that's less than ideal.

But here's some thoughts about another way... the thing we want to know is when the location of the stator changes with respect to the rim.

The internal hall sensors should trip at a very specific set of locations as the wheel rotates and these locations shouldn't change. Top Dead Center for cylinder 1, remember that (setting the points for y'all youngsters)? Let's say you hook up a hall sensor detector (I think a multimeter might work) and make a reference mark on the rim where the sensor trips. Then make periodic checks to verify that this the position doesn't change. You do have to at least get to the motherboard, and deal with the fact that your hall sensor connector will be getting plugged and unplugged—and that's a bad thing... connectors have cycle lifetimes. It probably won't be precise enough though.

If one was very clever, it would be possible to add an external "hall sensor" to the rim and electronically verify the relationship between when the rim sensor fires vs the internal sensor. Not trivial, but external hall sensors are used for bike speedometers so that part isn't rocket surgery. "Save and reliable" access to the internal hall sensor signal is another thing, as is the precision of the measurement. You don't need an absolute relationship, I think you just need to know if the relationship changes.

Interestingly, I would think that if you got really fancy in the wheel firmware, you could detect when the positional relationship of the hall sensors to how the motor phases are firing changed. I would think that if the hall sensors moved in their alignment to the stator magnets, that the timing and possibly the shape of the phase duty cycle would change as a consequence.

Another possible avenue for KS would be to use the sensorless system to determine if the relationship between where the sensorless system thinks the wheel is matches where the hall sensor thought the wheel was. I actually think this wouldn't be terribly difficult. The peak of the sensorless waveform should appear with a fixed timing relationship to the hall sensor... if this shifts start shouting "please repair"

 

Edited September 2, 2022 by Tawpie

[Paradox]

So how soon before the "New" Kingsong S-24 is announced?

[Tawpie]

A mechanical telltale might be possible... attach something to the rim and the stator and feed it out the motor wire hole so that if the rim slips relative to the stator it pulls the something back inside the motor.

I bet if we put our heads on it, a reasonable indicator is possible!

Not that this excuses KS or their motor vendor in any way.

[Planemo]

1 hour ago, Tawpie said:

But here's some thoughts about another way... the thing we want to know is when the location of the stator changes with respect to the rim.

I like your thinking, but it seems possible that the stator can slip enough in a single event to cause catastrophic power failure so any warning system would be pretty redundant. I accept that it might help if the stator only moves a bit, but the bottom line is that theres no way I would ride one of these wheels. Theres enough risk when riding EUC's as it is, let alone wondering whether my stator is gonna slip a bit (or a lot) 

[supercurio]

@Tawpie I thought about your idea but couldn't figure out how to make it work.

Is it possible to identify anything behind an aluminum side cover?
You could hide something in the tabs of the black plastic ring wrapping around the windings, which rotate with them in case of slippage.
The position of each tab is supposed to remain constant compared to the hub, one tab per base spoke, so if you can detect that one or several are not in their initial position anymore through the motor cover then the concept would work.

Edited September 2, 2022 by supercurio

[oolong]

I'd rather just have a new motor that's set properly without relying on a sensor.... and that goes for any mechanical part on the wheel.  No defects please.  if there is a defect found, recall the part and send me a new one.    If I'm going though the trouble taking out the motor then it'll be to install a brand new one, not to install a sensor to detect if there's a problem.

I expect a test from KS and if the motor fails the test, then I expect a new motor sent to me.  Better yet, send new motors to anyone who wants one if it was manufactured earlier than the date the defects were found.

[Tawpie]

13 minutes ago, Planemo said:

I like your thinking, but it seems possible that the stator can slip enough in a single event to cause catastrophic power failure so any warning system would be pretty redundant. I accept that it might help if the stator only moves a bit, but the bottom line is that theres no way I would ride one of these wheels. Theres enough risk when riding EUC's as it is, let alone wondering whether my stator is gonna slip a bit (or a lot) 

So true.

I'm looking for confidence and 'double check' here. Any motor can be poorly made and slip, these are especially poorly made so I'm trying to figure out if anything can be done to at least allow me to check.

[Planemo]

33 minutes ago, Tawpie said:

I'm looking for confidence 

I don't think I could find confidence in a test system which isn't infallible though. I do hear you, anything is better than nothing in the circumstances but I still wouldn't ride one even with the test system you describe. KS just need to replace affected motors, thats the only solution that would get me on one.

[Beachboy]

3 hours ago, supercurio said:

Source: reddit thread

This changed my opinion on the severity of this issue and how it should be addressed.
Noticing a faint scraping sound which disappear quickly, and reacting within 2s to another sound before cutting out is not something that can be expected from any rider.

With an expected failure rate between 5 and 15%, that's a lot of crashes and a lot more people getting injured.

Although the test is not confirmed nor official yet, I would now recommend every owner to complete the stress test on their wheel before riding it, especially new owners: first thing out of the box.
Either that, or recall.

Mine also have this faint scrapping sound only when turning sometimes, I used to ignored it just like what had  happend to my S18, with this issue I think I might open up the motor later just for peace of mind

Edited September 2, 2022 by Beachboy

[Funky]

If i had S20/22, i would simply return the wheel and ask for a refund. Plain and simple. As it simply defective product. (Even before this motor slipping/cutting wires, it already was defective..)

Would buy something better.

[supercurio]

9 minutes ago, Beachboy said:

Mine also have this faint scrapping sound only when turning sometimes, I used to ignored it just like what had  happend to my S18, with this issue I think I might open up the motor later just for peace of mind

Faint scraping sound only when turning sometimes: most likely the temperature sensor got pulled off after one or repeated stator slippage.
It's pretty light so it doesn't scrape very loudly, and can get tucked under something else so the scraping stops.

It also means that something's probably pulling on the phase wires right now, or is close to doing so. Danger zone.

Edited September 2, 2022 by supercurio

[Tawpie]

17 minutes ago, Beachboy said:

I might open up the motor later just for peace of mind

Definitely, I'd do that. It'd be very valuable if you took pictures

 

8 minutes ago, supercurio said:

the temperature sensor got pulled off after one or repeated stator slippage

to see if the faint scraping is an early warning sign—pulled off temp sensor should show up as a delta (cooler) in EUCWorld logs, at least I would think it would

[U-Stride]

This makes sense because before the cutout then fire, I mentioned in my video that I felt the motor slip on the  first emergency brake attempt then I attempted it again, this time it slipped and did not come back..the rest is history....🔥🔥 I hope no one encounters this while riding normally. Thanks a ton for this

Edited September 2, 2022 by U-Stride

[Beachboy]

26 minutes ago, Tawpie said:

Definitely, I'd do that. It'd be very valuable if you took pictures

Will do..I would need second opinion too actually

[supercurio]

30 minutes ago, U-Stride said:

This makes sense because before the cutout then fire, I mentioned in my video that I felt the motor slip on the  first emergency brake attempt then I attempted it again, this time it slipped and did not come back..the rest is history....🔥🔥 I hope no one encounters this while riding normally. Thanks a ton for this

I wish the motor had been open back then to see if the "slip" was the common controller over-power - pedal dip or the stator and its windings literally slipping over the base.
If it was the stator it would likely come with a "clunk" sound just like in the spin test. Maybe taking a second listen at the footage could tell.

[Tawpie]

7 hours ago, Paradox said:

So how soon before the "New" Kingsong S-24 is announced?

2 days before Master Y

[Tawpie]

@supercurio Do you think that the scary sounding clunk noise your wheel made during the stress test that blew it up was actually the stator sliding around? I'm just wondering if that's a real tell that the stator has broken free.

I'll need to get to the gym if routine stress testing is necessary, but it almost seems like there are some warning signs and you can force the failure with the stress test.

Maybe UStriding it (with your butt pads and flexmeters on) is a less back breaking technique?

Edited September 3, 2022 by Tawpie

[supercurio]

22 minutes ago, Tawpie said:

@supercurio Do you think that the scary sounding clunk noise your wheel made during the stress test that blew it up was actually the stator sliding around? I'm just wondering if that's a real tell that slippage is in process.

Exactly, that's the current theory: each clunk being the stator breaking free and sliding.

What would confirm it:
MyEWheel receiving 5x air-shipped units with July motors which all passed the spin test without any clunk.

What would infirm it:
Voltride opening a clunky-motor after a spin test but observing no slippage visually, including a pristine temp sensor silicone glue spot in between the motor base and the stator.

More testing is needed, at larger scale and with precise measurements to evaluate if it's a valid stress test or not.
I hope it is.

22 minutes ago, Tawpie said:

I'll need to get to the gym if routine stress testing is necessary, but it almost seems like there are some warning signs and you can force the failure with the stress test.

Maybe UStriding it (with your butt pads and flexmeters on) is a less back breaking technique?

For me the S22 with its current firmware has been too strong to pedal dip on flat ground during hard braking (except one time from 60kph+ - slightly) No clunk sound then.
Maybe 10+ minutes of cumulated spin test would kill a bad motor without any riding.
What did it on my unit was:

• 3-5x spin test sessions as shown in the video (I forgot the exact count)
• 1x super slow ride to unlock the wheel (not sure if that count): no issue
• 1x 30km fast paced ride: no issue
• Next ride: first sign (light scraping) appeared randomly after 5km

I don't believe there's a safe way to introduce the failure while riding the wheel, it's a risky gamble, please don't try 🙏

Edited September 3, 2022 by supercurio

[Elliott Reitz]

I I got my wheel in March.  It still makes this sound sometimes.  I could be the fender, but I doubt it.  There is no interferences.  I did do the spin-test on it today.  No clunking from that.  

From the 1st page photos, I often wonder about the magnet clearances when I see these motors open.  There's obviously a performance improvement to tighter tolerances but too tight with expansion/contraction and impacts cold be causing interferences to various degrees of effect that could include breaking loose and moving the stator.  

{edit+}

400 miles later its still present in this slow ride today (only 400 because It failed controller/bats from May to end of July).  

A possibly related problem - would be the pedal-dip like Wrong-Way's videos showed on stairs?  Well today I was doing lots of root-climbing similar to small to medium curbs.  Anyway it cut out on me when I attempted a 6" root impact (I was going about 4mph).

 

Edited September 4, 2022 by Elliott Reitz
spelling

[InnerBarrel]

Would opening up the motor and adding some crazy glue be a good idea for safety ?

I hope KS can surive this as important certain they are busy right now

[Elliott Reitz]

9 hours ago, InnerBarrel said:

Would opening up the motor and adding some crazy glue be a good idea for safety ?

I hope KS can surive this as important certain they are busy right now

I wonder if it could be screwed in via drilling and taping holes through the tabs into the stator-frame.