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

[supercurio]

@FlyboyEUC shared 2 cases he found:

Raymond Brock - Developped into a hall sensor issue, has cut out while riding 
https://www.facebook.com/groups/1876404869187267/permalink/2166941156800302/

Mika Lanery - brand new wheel, scraping sound coming from the motor. To investigate..
https://www.facebook.com/578553330/videos/618465533140052/

[Forwardnbak]

1 hour ago, supercurio said:

 

Mika Lanery - brand new wheel, scraping sound coming from the motor. To investigate..
https://www.facebook.com/578553330/videos/618465533140052/

is this the new motor? post July? 

[supercurio]

13 hours ago, BIGboiFASTboi said:

I mentioned this earlier but nobody replied.... Anyone willing to try a pendulum test?  Rock back and forth while standing along a wall, and torque the wheel 200 times in quick succession to stress test the motor and control board.

It's certainly a test and feasible, but over-powering the wheel 200 times will be both a very technical and physical endeavor.
Note that the stalled motor safety might limit the torque and make the test moot.

You can certainly try and report your findings!

4 hours ago, 5Cauac said:

Perhaps but..........

I performed the stress test three times and pass (although not as aggressive as others) and a few drop tests by jumping, spinning up the wheel and landing on tabletop jumps at the bike park and passed. HOWEVER..........this past weekend I hit a root with my pedal while taking a berm, lost control and stepped off the wheel. The wheel came to an abrupt, immediate stop as I was tethered to the suspension arm, and burned the mother board.

Oh damn. Thanks for the detailed description, you seem to have handled that well (no injury)

4 hours ago, 5Cauac said:

I heard the "loud snap/squeak" of the stator slipping after reviewing the video and determined it was the cause the burned out MB. 
Video of the whole ordeal and the rescue from the forest with my S18 will be out soon. Currently working on it. 😎

If there was a suspicious sound, you think it could not only the board but the motor as root cause?
It could be wise to open and check the motor before installing a new board then, indeed.

 

52 minutes ago, Forwardnbak said:

is this the new motor? post July? 

Brand new wheel, just received but motor built in on April 03 😔

[Tawpie]

4 hours ago, 5Cauac said:

@Tawpie I was thinking along the same lines as you were regarding the Tilt Cutoff Angle, mine is set to 70° however I don't think to comes to a "Hard" stop when activated. It just cuts the power. 

In that case, the early failures of simply tipping over and killing the motherboard don't have a good explanation (I'll always blame firmware first though). Several of those wheels have been fixed with just a motherboard replacement, no motor change (ie: the motor didn't slip enough to short things out).

Your case being stator slip, it's different than what I'm thinking about re the early failures in Toronto and here.

Edited September 21, 2022 by Tawpie

[supercurio]

Progress update:

It's been a while since the last one, as I prioritized interactions with the dealers and King Song with a lot ongoing on these fronts.
Here's a condensed version of the most important aspects:

Fixed motor revision details

We learned that the July+ motors got a series of changes, including:

• pins added to the stator interface in order to prevent the issue mechanically. Source: King Song engineering.
• new bearings size:  6812 on original vs 6912 on the new one. Source: Jason / eWheels

Russians are fixing motors on their own

Fun fact, I learned about the pins in the new motors from a comment from KS engineering after he saw what the Russian community came up with.

Instructions are:
If you drill yourself, you need to drill here: 2,5mm. (source)

The gap in the stator interface viewed under the microscope

source: Aleksandr Vladimirovich on Telegram

 

 

Deprecation of the spin test

Dealers in the group started (with moderate/low confidence) to test all wheels. Some being a little shy, some going all in with a very long version of the spin test at maximum rpm. Then yesterday we had the first motor failure in the hands of a customer for a motor who passed the test "with flying colors". A single instance is sufficient to prove a test unreliable, so that was it.

Today, when exchanging with King Song on the topic of announcement I realized that they also eliminated the spin test as tool. Only the landing test remains; same as what I described in the original post.
It creates the absolute maximum stress on the stator interface, and when executed correctly it'll typically kill a motor with an Error 13 (hall sensor) safely. I saw a video of how they conduct it internally: it's a workout, to put it mildly.

 

Edited September 22, 2022 by supercurio

[Tawpie]

recall them all.

(but that's just my opinion)

Edited September 22, 2022 by Tawpie

[5Cauac]

Thank heavens for @U-Stride's fire incident, otherwise KS would have never made the SW/FW updates and......well you can imagine the rest. 

[gon2fast]

I like my S22, but I will be damned if I buy another KS product if they don't step up and get root cause analysis completed on these issues. It is absolute BS that they have been silent (other than to say that there is no issue) and more so, it is not the consumer's responsibility to find manufacturing defects.

Sorry for my complaining, but KS established their own channel on this forum to advertise the S20/22 and now we get nothing from them... oh sorry, a few FW upgrade that do not address anything. 

The lack of transparency really pushes my buttons LOL.

Once again, I like my S22, but King Song is clearly in last place amongst EUC companies right now.

[Tawpie]

1 hour ago, gon2fast said:

King Song is clearly in last place amongst EUC companies right now.

They've sunk to the levels we've come to accept... there was hope after the fire (and we promptly called BS and wanted fuses or some arbitrary hardware change), but sadly that seems to have disappeared. IM said "we might have a problem" then went silent. BG never says anything except "look at the new shiny!". LK has always been pretty much crickets (ok, they said Abrams would be fixed in firmware). EB?

I guess, why be open when nobody else is? Being open just gives us in the peanut gallery more fodder for Monday morning quarterbacking.

Edited September 22, 2022 by Tawpie

[Eucner]

9 hours ago, supercurio said:

• new bearings size:  6812 on original vs 9612 on the new one. Source: Jason / eWheels

The bearing size 9612 is not relevant to EUC's. Could it actually be 6912? This change is not for the stator slippage problem. 30% wider bearing would help for bearing alignment problem.

[supercurio]

6 minutes ago, Eucner said:

The bearing size 9612 is not relevant to EUC's. Could it actually be 6912? This change is not for the stator slippage problem. 30% wider bearing would help for bearing alignment problem.

Probably a typo indeed, I simply copy-pasted. Good catch!
Yes hopefully larger bearings will help, provided the tolerances of the side covers are improved as well.

[chanman]

I'm glad that there's a concrete solution to the problem in the newer motors, and presumably improved bearings is a nice bonus.

[WILSONEUC]

Was looking on alienrides and saw that they had this wheel. Would you say "wait" on this one? 

[UniVehje]

4 hours ago, CyberV0LT said:

Was looking on alienrides and saw that they had this wheel. Would you say "wait" on this one? 

Absolutely wait! Unless you want a DIY project as a hobby. It’s not just the motors that are faulty. 

[Rawnei]

6 hours ago, CyberV0LT said:

Was looking on alienrides and saw that they had this wheel. Would you say "wait" on this one? 

If you can get 3D printed or CNC sliders and install those this wheel rides like a dream, otherwise could be better to wait for KingSong official solution (which they are slowly working on).

[supercurio]

Progress update:

Growing reach

The amount of people understanding the stator slippage issue is increasing quickly in the community, and more customers are testing their own wheels now, although they do so with the spin test which we know today is not sufficiently reliable.

• spin test kills a motor or mainboard: conclusive
• spin test pass: not conclusive

The landing test (described in first post) is hard to complete but expected to be reliable.

Examples:
https://www.facebook.com/578553330/videos/618465533140052/
https://www.facebook.com/100000089638050/videos/483401076982855/ (test: fail)

Begode T4: same same

The Begode T4 motor is made by the same supplier: ZX
Begode chose ZX for the T4 version of their "C30" motor instead of HB, but didn't switch at the right time.

Here's Chance Hintz T4 motor: notice anything similar?

Unfortunately yes, the T4 motor is affected by exactly the same stator slippage issue as the S22.
Quoting Chance (source: Facebook)

Quote

Yes be carful I had a motor make a similar noise (on a begode wheel) same issue Stator wire rubbed and cutout and shorted motherboard

A friend and local Stockholm rider had the same experience with his own brand new T4: the issue is likely widespread.

On public announcement

Work still ongoing, there's progress. Something to happen next week maybe? 🤞

Edited September 23, 2022 by supercurio

[Paradox]

1 hour ago, supercurio said:

Unfortunately yes, the T4 motor is affected by exactly the same stator slippage issue as the S22.

Which other wheels now being sold are manufactured with motors by the ZX company?  Is this a heads up to avoid wheels with  ZX motors?

Edited September 23, 2022 by Paradox

[supercurio]

@Paradox Inmotion wheels are using ZX motors but there has been no such issue reported so far.
However, definitely something to pay attention to for recently produced units - just in case.

[litewave]

7 hours ago, UniVehje said:

Absolutely wait! Unless you want a DIY project as a hobby. It’s not just the motors that are faulty. 

Really, hasn't that always been the case? Even the highly-praised Ninebot Z10 had a high failure rate initially according to eWheels (the highest at that time, exceeding even Gotway).

[litewave]

On 9/21/2022 at 4:06 PM, Elliott Reitz said:

Agreed. However, something with a friction-fit and glue may NEVER loosen too.  A 1x stress that doesn't break it doesn't prove that to be the case, but the way static vs sliding friction works that's likely to be the case for the press-fit-friction element.  As for glue it can "break" in a similar manor.  So passing a stress test of any form is a good indicator, but not a proof.

I do lots of jumps and curb drops, etc.  That's why I needed suspension to start with. 

The hard-breaking that I did is only another form of a 1x stress test.  IDK if its as stressful to the motor as jumps or free-spin-reversal.  But it is much more real-world to me where I don't normally put that much torque on the wheel.   That particular time I had an emergency stop situation with a new seat to grab.  It worked better than I had imagined it could have. 

Again not proof.  

Agreed.  Stress test only indicates it hasn't failed yet while risking immediate failure.  Immediate failure may be better than unexpected failure, especially at speed.  However, stator slip is torque induced not speed induced.  Sure at highest speeds the motor is consuming the most power - but that doesn't translate directly into the stator interface force.  Thus I'm more concerned about slippage on steep climb or emergency breaking situations.  And hay note that the S20 fire of U-Stride/Saing was preceded by a breaking induced slippage sensation.  

Totally agree with your sensible perspective. I'm certainly grateful that we have discovered the stress test but suspect that if we start testing our older wheels many of them would fail also.

[5Cauac]

As promised.........

0:00 Preview
01:09 Intro/S22 issues
4:02 Suspension and Torque talk
7:02 Black Diamond trail run (Ridge Trail)
8:59 Blue Square trail run (Flow Trail)
11:56 Motor and Mother Board failure
12:54 The rescue plan
15:47 A very exhausting and wet rescue
17:23 Successful rescue

 

 

[FunTech4Real]

I read everything on this thread and I have a S22 from ewheels... Mine passed the tests for the motor... but there is another issue with the S22 that no one is talking about... The controllers keep dying. Mine died when I was placing the wheel down on its side in grass... I put it down a little too fast and it caused the tire to spin into the grass which made the entire unicycle rotate about a half turn, which killed the controller. Shibby time has supposedly gone through 3-4 controllers... and there are many other stories of similar controller issues. The controller death appears to be related to high torque situations at low speeds, such as landing from a jump, because the tire may be spinning backwards while in the air due to the uneven weight distribution of the unicycle, then the tire needs to immediately start spinning forward. The good news it is does not seem that the controller issues happen at high speeds... but this has made me afraid to do any jumps on this wheel (one of the main reasons I bought it). After my controller died, I plugged the wheel into the charger to see if it would do anything... and within a matter of seconds the charger started smoking (potential fire hazard). Ewheels is shipped me a new controller, motor, and charger immediately (their support is way above and beyond every other EUC dealer out there - thank you @Jason McNeil). See my facebook post for a video - which includes the charger smoking when I plugged the dead wheel in (and see the comments for others talking about the same controller death issue)!

https://www.facebook.com/75401032/videos/1455728894950625/

[Eucner]

On 9/22/2022 at 2:42 AM, supercurio said:

This is appropriate place to drill and tap the set screw.

On 9/22/2022 at 2:42 AM, supercurio said:

This drawings shows wrong place to drill. It wouldn't mechanically lock parts together.

Edited September 23, 2022 by Eucner

[techyiam]

9 hours ago, Paradox said:

Which other wheels now being sold are manufactured with motors by the ZX company?  Is this a heads up to avoid wheels with  ZX motors?

I believe my V12 has a ZX motor in it. It has been totally fine so far.

[supercurio]

1 hour ago, Eucner said:

This is appropriate place to drill and tap the set screw.

This drawings shows wrong place to drill. It wouldn't mechanically lock parts together.

I know what you mean, there's a picture I forgot to add here which makes the drawing cleared.

In green, where the hole would be drilled. As the view under the microscope shows, it goes throu the lip on the motor base and into the stator itself. It's not exactly how the pictures are showing. I think that this is what the Russians are doing now.

I made without confirmation from the inventor of this method so please correct me if I'm wrong.