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

[5Cauac]

14 minutes ago, Elliott Reitz said:

OMG you got a motherboard too?  Want to sell it? 

Sorry buddy but I need this one.
I actually lucked out that Jason over at eWheels saved one of each from the original batch he received to replace bad motors and blown boards.  He is still waiting on the ones that were due to go out by air.

[Elliott Reitz]

The more I think of it, the more I disagree with the "stator tests" that have been described.  There is a firmware torque limit that cuts out that these "stator tests" don't even reach. I'm not saying the "stator test" as promoted here can be used to find a defect while killing a wheel.  But it doesn't prove the motor is ok.   These tests are not directly applying a measured repeatable level of torque that proves a wheel is OK.

A better test:  At 5 mph push on a car so hard that the wheel cuts-out.   This would test the to the firmware's repeatable torque limit. Of course KS has already manipulated that limit at 0mph and a few feet staring to protect the undersized the MOSFETS.  Next issue is that the stator torque limit is below the firmware limit. If pushing a car tests the firmware torque limit then the hardware torque limit would be 'proven' defect free (but even then, only at that temperature).  So to fully verify a working wheel would require both min/max ambient temperature repeat-test. Like leave the wheel in a freezer on a charger at 0 F and then try the car-push-test.  Repeat 

PS: If the MOSFETS were properly derated then a single phase MOSFET with best cells at 0 mph would produce maximum torque. So the MOSFETS aren't 66% derated (oversized) as they should be.  So I'm also saying KS skimped on max torque at 0mph via undersized (cheaper by a few $) MOSFETS. 

Edited September 29, 2022 by Elliott Reitz

[chanman]

It doesn't seem that motor output is really the troubling factor here, it's the sharp change in force (impulse?) going from no resistance to high resistance instantly, I don't think the car pull/push test is really what we're looking for for the slippage test.

I can't comment on the mosfet suitability, we do seem to be seeing more controller failures than ideal but it's not clear to me if that issue is the hardware, the firmware, or complications from the motor issues.

Edited September 29, 2022 by chanman

[Elliott Reitz]

6 minutes ago, chanman said:

It doesn't seem that motor output is really the troubling factor here, it's the sharp change in force (impulse?) going from no resistance to high resistance instantly, I don't think the car pull/push test is really what we're looking for for the slippage test.

I can't comment on the mosfet suitability, we do seem to be seeing more controller failures than ideal but it's not clear to me if that issue is the hardware, the firmware, or complications from the motor issues.

Bullshit.  By drop testing or reversal testing the rotor is what's being abruptly torqued.  The force that makes it to the stator is electrical only.  And like torque-hp trade at speed for gas-power motors, slower speeds feature torque, higher speeds feature HP.  So max torque isn't max speed spin.  

Max torque is a slow speed maximum force which has a firmware cutout limit.  Its time we "overtorque" this wheel.  That's the only valid test. 

PS:  My S22 is dissassembled because of another controller failure.  Not just the motor mosfets are undersized (only survive thanks to firmware protection).  The battery protection MOSFETS that switch the batteries has failed on me repeatably.  Again undersized transistors is the leading speculation (and I'm an engineer with 40 years experience... measured 20V between charger and battery ground before replacing the controller and batteries).  

Edited September 29, 2022 by Elliott Reitz

[chanman]

I mean if you want to push the wheel to its limits to see if you can burn the board that's perfectly fine. I think you can do this on several wheels. @supercurio I think has a pull force test thread and a number of wheel casualties, not sure if the S22 is on the list. 

I don't think that's the best test for the stator slippage though, the "landing test" seems to be suited to this, you don't want to gradually build up to maximum force, you want to force a sudden change.

Edited September 29, 2022 by chanman

[daniel1234]

1 hour ago, Elliott Reitz said:

A better test:  At 5 mph push on a car so hard that the wheel cuts-out.   This would test the to the firmware's repeatable torque limit. Of course KS has already manipulated that limit at 0mph and a few feet staring to protect the undersized the MOSFETS.  Next issue is that the stator torque limit is below the firmware limit. If pushing a car tests the firmware torque limit then the hardware torque limit would be 'proven' defect free (but even then, only at that temperature).  So to fully verify a working wheel would require both min/max ambient temperature repeat-test. Like leave the wheel in a freezer on a charger at 0 F and then try the car-push-test.  Repeat 

PS: If the MOSFETS were properly derated then a single phase MOSFET with best cells at 0 mph would produce maximum torque. So the MOSFETS aren't 66% derated (oversized) as they should be.  So I'm also saying KS skimped on max torque at 0mph via undersized (cheaper by a few $) MOSFETS. 

I second that! Free spin is questionable. 

 

[Slartibartfast]

I'm currently trying to diagnose a noise I'm hearing from an (pre July) S22.

This wheel belongs to a friend and he has had no end of issues with it, the current issue being that it makes an annoying "buzzing" sound whenever powered on. This sound gets better and worse on occasion but when it's bad it's very, very bad, and even when it's good it's still pretty bad. Note this sound happens all the time, even when stationary.

I see in the opening post it says a symptom of a slipped stator is:

• motor tremors and vibrations at low or no speed (not officially recognized)

but this symptom hasn't been mentioned again anywhere in the following 13 pages. This symptom however seems consistent with what I'm seeing –although it has to be said the wording really doesn't do justice to the horrendous racket the wheel makes. "Warm up act for Disaster Area plutonium rock band" would be a more apt description if you catch my drift: 

 

Anyway, here is a clip trying to show the issue:

 

Any idea what is going on here?

Note we have contacted the dealer several times and the suggestion has been "do the bolts up tighter" which, arr, doesn't help: 

Edited September 29, 2022 by Slartibartfast

[daniel1234]

yes this looks hall misplaced causing vibration ... motor problem / feature.

[Slartibartfast]

13 minutes ago, daniel1234 said:

yes this looks hall misplaced causing vibration ... motor problem / feature.

Surprisingly, although it makes a horrendous racket the wheel and motor actually seem to function perfectly fine, although none of us are actually willing to ride it: 

Any idea how "hall misplaced" would cause such vibration? And if so why it still wheels and essentially functions correctly with the hall sensors misplaced?

I am completely baffled by it. 

 

Another thing I don't understand is that wiggling the motor wires between the motherboard and motor dramatically changes the volume of the buzzing: 🤷‍♂️

(note in the video I'm just placing my had on the mudguard when the sound changes rather than wiggling the cables)

Edited September 29, 2022 by Slartibartfast

[supercurio]

8 hours ago, 5Cauac said:

A shiny new "S22" stamped motor manufactured on the 2nd day of July, 2022.   

That's good stuff! Fantastic job from the dealer to get you all that so quick.
Regardless if your original "S20" S22 motor went bad or not, you were supposed to eventually get a replacement, so.. might as well replace both in one go: makes sense.

I don't have confirmation yet, but I presume that the "S22" stamped side covers match the larger bearing size.

8 hours ago, Tawpie said:

From what I've heard, the "fix" didn't go in until sometime in July, and yes, motors that have slipped were made before July

July is good as well as a few of the last days of June. No authoritative answer on that.

 

7 hours ago, Elliott Reitz said:

The more I think of it, the more I disagree with the "stator tests" that have been described.  There is a firmware torque limit that cuts out that these "stator tests" don't even reach. I'm not saying the "stator test" as promoted here can be used to find a defect while killing a wheel.  But it doesn't prove the motor is ok.   These tests are not directly applying a measured repeatable level of torque that proves a wheel is OK.

The firmware limit is applied quickly after the motor is stalled, I could confirm that during my pull force test (still need to edit the video BTW)

7 hours ago, Elliott Reitz said:

A better test:  At 5 mph push on a car so hard that the wheel cuts-out.   This would test the to the firmware's repeatable torque limit. Of course KS has already manipulated that limit at 0mph and a few feet staring to protect the undersized the MOSFETS.  Next issue is that the stator torque limit is below the firmware limit. If pushing a car tests the firmware torque limit then the hardware torque limit would be 'proven' defect free (but even then, only at that temperature).  So to fully verify a working wheel would require both min/max ambient temperature repeat-test. Like leave the wheel in a freezer on a charger at 0 F and then try the car-push-test.  Repeat 

The low speed threshold is not known for the stalled motor. Difficult to figure it out via trial and error without very controlled conditions. You can certainly try the test you're suggesting, once you get a wheel back in order. Please report!

7 hours ago, Elliott Reitz said:

Bullshit.  By drop testing or reversal testing the rotor is what's being abruptly torqued.  The force that makes it to the stator is electrical only.  And like torque-hp trade at speed for gas-power motors, slower speeds feature torque, higher speeds feature HP.  So max torque isn't max speed spin.

I think it is abruptly torqued as well.
The proof is in the pudding anyway, the test was shown to be effective introducing the fault, observed as Error 17 by Kingsong QA team. I saw the internal videos of them doing it.

Now if we can find a test that's at least as effective and easier to run, that would certainly be good news.
Not as good news as a replacement of all motors, but.. yeah.

7 hours ago, Elliott Reitz said:

Max torque is a slow speed maximum force which has a firmware cutout limit.  Its time we "overtorque" this wheel.  That's the only valid test. 

Just like an impulse contains all sound frequencies in a single signal (commonly used in the field of acoustics) the landing test also stresses the motor and controller with all the speeds at once.
That includes 0 rpm torque. Enough to trigger stator slippage, not enough to burn the mainboard.

 

7 hours ago, chanman said:

I mean if you want to push the wheel to its limits to see if you can burn the board that's perfectly fine. I think you can do this on several wheels. @supercurio I think has a pull force test thread and a number of wheel casualties, not sure if the S22 is on the list.

I don't think that's the best test for the stator slippage though, the "landing test" seems to be suited to this, you don't want to gradually build up to maximum force, you want to force a sudden change.

Yes the S22 handled the pull force test like a champ with both firmware versions I tested. It felt strong for an insta... oh no actually pretty weak now. In that case, the current & torque throttling was working reliably to protect the mainboard.
Then the value measured was nowhere near the real torque experienced while riding.

[Eucner]

8 hours ago, 5Cauac said:

Does anyone know if they started stamping S22 starting in July or are there any motors stamped prior to July with S22 but known to have the stator issue?

You need to open S22 motor to be sure. I'm also curious to know how they have secured pins to stay in place. If there is a possibility for steel pin to walk out and touch motor cover, it would have serious results. Small aluminium particles could jam or short the motor. Finally the pin could cut through the cover and lead to certain EUC crash.

I would only trust pins staked with punch or press tool.

[supercurio]

52 minutes ago, Slartibartfast said:

I'm currently trying to diagnose a noise I'm hearing from an (pre July) S22.

This wheel belongs to a friend and he has had no end of issues with it, the current issue being that it makes an annoying "buzzing" sound whenever powered on. This sound gets better and worse on occasion but when it's bad it's very, very bad, and even when it's good it's still pretty bad. Note this sound happens all the time, even when stationary.

I see in the opening post it says a symptom of a slipped stator is:

• motor tremors and vibrations at low or no speed (not officially recognized)

but this symptom hasn't been mentioned again anywhere in the following 13 pages. This symptom however seems consistent with what I'm seeing –although it has to be said the wording really doesn't do justice to the horrendous racket the wheel makes. "Warm up act for Disaster Area plutonium rock band" would be a more apt description if you catch my drift: 

 

Anyway, here is a clip trying to show the issue:

 

Any idea what is going on here?

Note we have contacted the dealer several times and the suggestion has been "do the bolts up tighter" which, arr, doesn't help: 

Fortunately, that's a different issue:

Look in this video showing the same problem (with timestamp)

Solution in the following video:
In short: mainboard screws need to be tightened (reasonably)

 

Edited September 29, 2022 by supercurio

[Slartibartfast]

18 minutes ago, supercurio said:

mainboard screws need to be tightened (reasonably)

Hehe, just "do the bolts up tighter" you reckon hey?
We've really done them up pretty dang tight already and it seems that no amount of tightening stops the buzzing. That's actually why the cover is removed in the first place.

But even if we were able to tighten every single thing so much that is stops buzzing it still seems wrong that it even vibrates at all. I mean where is the actual vibration coming from? You can place your hand almost anywhere on the EUC and feel it vibrating. Why on earth does it do that? Do other S22 vibrate all the time?

Edited September 29, 2022 by Slartibartfast

[supercurio]

@Slartibartfast ah shoot. Back to your dealer then, and if it's not a screw the motor could be checked.

To give a sense of the tremors that can occur when due to stator slippage, for me it was not the kind that starts vibrations or oscillations and make the wheel rattle.
Instead, it's something that could be felt via the pedals and body of the wheel, but not enough to become audible.

Have you completed any of the stress tests?

[Slartibartfast]

12 hours ago, supercurio said:

Have you completed any of the stress tests?

It's not actually my wheel and I don't have it here with me and unfortunately didn't know about the "stress tests" till reading this thread so no, I haven't done the tests, which is a shame as I would like to know myself.

It is worth noting though that the motherboard did short out for some reason a little while ago and has been replaced. The wheel really hasn't been ridden very hard and is actually owned by a 60yo emphysema sufferer and is more used as a mobility scooter than anything (I know, go figure: ) so it really hasn't been treated that harshly in it's relatively short life. As to why the board died I have no idea but I can assure you it was not due to aggressive riding. The owner says he was riding fairly gently when it just cut out (perhaps 15km/h) and wouldn't turn on again until the board was replaced. I don't know if that's related or not but after that he had an issue with the charger and now this.

I have to say we're really pulling our hair out over this. Had such high hopes for this wheel and it's been nothing but tears and disappointment: 😔

Edited September 30, 2022 by Slartibartfast

[RolluS]

6 hours ago, supercurio said:

July is good as well as a few of the last days of June. No authoritative answer on that.

Good to know, ZX reported the problem to the T4 then... (ironic kidding)

Chance's motor:

@supercurioyou said "Good catch and bad news, meaning that ZX fixed it on the S22 motor in July but not on the T4.
I asked my friend and will report." Is it confirmed if/when they fixed on T4 please?

Edited September 29, 2022 by RolluS

[Finn Bjerke]

7 hours ago, Slartibartfast said:

I'm currently trying to diagnose a noise I'm hearing from an (pre July) S22.

This wheel belongs to a friend and he has had no end of issues with it, the current issue being that it makes an annoying "buzzing" sound whenever powered on. This sound gets better and worse on occasion but when it's bad it's very, very bad, and even when it's good it's still pretty bad. Note this sound happens all the time, even when stationary.

I see in the opening post it says a symptom of a slipped stator is:

• motor tremors and vibrations at low or no speed (not officially recognized)

but this symptom hasn't been mentioned again anywhere in the following 13 pages. This symptom however seems consistent with what I'm seeing –although it has to be said the wording really doesn't do justice to the horrendous racket the wheel makes. "Warm up act for Disaster Area plutonium rock band" would be a more apt description if you catch my drift: 

 

Anyway, here is a clip trying to show the issue:

 

Any idea what is going on here?

Note we have contacted the dealer several times and the suggestion has been "do the bolts up tighter" which, arr, doesn't help: 

Who is the dealer if I may ask? 

[Mika47]

21 hours ago, 5Cauac said:

Regardez ce qui est arrivé dans le courrier aujourd'hui !! 
Un nouveau moteur estampillé " S22 " brillant fabriqué le 2 juillet 2022.   

Cool !!! Can you check the reference of bearing please ? 😊 (old 6812RS).

You will open the new motor for see into ? 🙄😇

[Slartibartfast]

6 hours ago, Finn Bjerke said:

Who is the dealer if I may ask? 

Probably best not to say at this stage as it seems things are starting to get a little tense but I'll let you know when it's all resolved.

[Tawpie]

19 hours ago, Slartibartfast said:

Surprisingly, although it makes a horrendous racket the wheel and motor actually seem to function perfectly fine, although none of us are actually willing to ride it: 

When you engage the 'lift switch' by opening/dropping the back handle, does the noise stop? Engaging the lift switch will cut motor power and that should make the noise stop if the noise is related to motor drive. I don't think it's hall sensors or it wouldn't balance, would beep a lot, show an error, and might blow the motherboard when you move it back and forth. If the noise continues when the motor is disengaged by the lift switch (be sure the lift switch is set to active in the app!), then the vibration might be coming from the mainboard and the mainboard should never ever vibrate. Ever. If it's not the mainboard it has to be the batteries and I can't think of any way they'd vibrate—even under a fault condition.

It certainly sounds like something plastic is vibrating and being able to change the tone by touching it is supporting evidence, but nothing should be vibrating that much. Something bad is happening and I'm guessing it's bad in the motor. But you could try pressing on plastic things to see if you can locate a spot to press that'll make the noise go away, that would help pinpoint the source. Maybe see if moving the motor cable does anything. See if you can feel where the vibration is strongest.

If there's any way, return to vendor. The end consumer should not have to deal with this, something is clearing not right.

Edited September 30, 2022 by Tawpie

[Slartibartfast]

1 hour ago, Tawpie said:

When you engage the 'lift switch' by opening/dropping the back handle, does the noise stop? Engaging the lift switch will cut motor power and that should make the noise stop if the noise is related to motor drive. I don't think it's hall sensors or it wouldn't balance, would beep a lot, show an error, and might blow the motherboard when you move it back and forth.

I didn't actually think to try the 'lift switch' however I did try turning the wheel on while it was tilted back on its own stand and the vibrations didn't start till it was stood upright and started stabilizing. It's pretty clear that the vibrations are linked to the motor being activated.

As I mentioned before it also seems the vibrations are somehow related to the power cables connecting the motherboard and the wheel.

Here's another clip: (oh and fair earphone warning)

 

1 hour ago, Tawpie said:

If there's any way, return to vendor. The end consumer should not have to deal with this, something is clearing not right.

Yeah, that's what we are currently dealing with.

Edited September 30, 2022 by Slartibartfast

[Slartibartfast]

At the end of it all though, I take it this is not necessarily symptomatic of a "slipped stator", which is why I originally joined the discussion, no?

Edited September 30, 2022 by Slartibartfast

[Elliott Reitz]

On 9/28/2022 at 11:59 PM, chanman said:

I mean if you want to push the wheel to its limits to see if you can burn the board that's perfectly fine. I think you can do this on several wheels. @supercurio I think has a pull force test thread and a number of wheel casualties, not sure if the S22 is on the list. 

I don't think that's the best test for the stator slippage though, the "landing test" seems to be suited to this, you don't want to gradually build up to maximum force, you want to force a sudden change.

Thanks @chanman and others for considering my alternate to the spin test.  The most impressive response is that the spin-drop test may apply max firmware torque when the wheel stops (before it would cut-out).  If it doesn't cutout but just stops after some force then again i would say its not a max torque repeatable like the pushing/pulling of a car at low-speed into a cut-out.  The key is getting to cut-out level force.  

And I've gotten to cut-out level force via failed root and curb climb attempts on S18, MSX100V, and my S22.  Since I've had that max-torque cutout on my S22 I'm satisfied its "tested" at 80 deg F.  Note that a significantly different temp could dramatically change the slip-torque threshold of the press fit stator.  

On 9/29/2022 at 8:21 AM, Slartibartfast said:

It's not actually my wheel and I don't have it here with me and unfortunately didn't know about the "stress tests" till reading this thread so no, I haven't done the tests, which is a shame as I would like to know myself.

It is worth noting though that the motherboard did short out for some reason a little while ago and has been replaced. The wheel really hasn't been ridden very hard and is actually owned by a 60yo emphysema sufferer and is more used as a mobility scooter than anything (I know, go figure: ) so it really hasn't been treated that harshly in it's relatively short life. As to why the board died I have no idea but I can assure you it was not due to aggressive riding. The owner says he was riding fairly gently when it just cut out (perhaps 15km/h) and wouldn't turn on again until the board was replaced. I don't know if that's related or not but after that he had an issue with the charger and now this.

I have to say we're really pulling our hair out over this. Had such high hopes for this wheel and it's been nothing but tears and disappointment: 😔

I've had that "Buzzing sound" issue on 2 wheels.  Both by trying to figure out the charging issue I measured 20V between battery ground and charger ground.  When I shorted the grounds together to get it charging, that worked.   I caught on to it when my 1st S22 developed a no-charge problem.  When I got the 2nd S22 it failed to fully charge reporting over/under voltage of a pair of cells.  I measured the cells by hand and they were fine (a/d circuit maybe?  Ground alignment maybe?

After swapping around batteries and controllers KS recommended cutting the small green wires that go to the batteries.  1st one, then another, then twist them together.  That got it charging but introduced that buzzing (with the 2nd controller).  That time the wheel would would go 10mph before the buzzing started.

My impression:  KS firmware upgrades enabled undersized ground-switches between the batteries and controller.  Those fail.  And this past Monday my 3rd controller reported Er 17 Hall sensor (common error when the stator slipps).  So I opened the motor and there is no visible slip.  So I again believe the most likely culprit is the failure of the undersized ground switching on the controller introducing a voltage offset to the hall circuit.

7 hours ago, Slartibartfast said:

At the end of it all though, I take it this is not necessarily symptomatic of a "slipped stator", which is why I originally joined the discussion, no?

Exactly.  The buzzing is most likely a transistor failure on the motherboard. 

Gotway T4 got a Stator Slip reported by Chance Hinz (on FB) 

We shouldn't be too surprised this is happening.  Why?  Well our high power wheels ARE the Most Advanced Hub Motors to date.  So I'm speculating (again) that these stator-frames with pressed on Stators are common to most if not all hub motors.  Yet the biggest and highest hub motors yet produced are EUCs.  When its an ebike or something like an old e+ stator just didn't have the force to slip.  But with high torque wheels, we found out the hard way. 

Bottom line (opinion) - All new EUCs with over 2000 W power should be disassembled for the insertion of the 5mm set screw.  (I will skip my old MSX100V and my S18).  But I'm putting the pins in my S22 and also into my Master when it arrives. 

Make the upgrade (this winter)!  

• Drill and Tap kit:  Hakkin 9 Pcs Adjustable T-Handle Tap Holder Wrench, Machine Thread Taps Set Tapping Threading Tool Set with 4 Pcs Metric Taps Set (M3-M6 Taps), 4 Pcs Drill Bits - - Amazon.com
• Set screws: VIGRUE 300Pcs M2.5/M3/M4/M5/M6/M8 Hex Allen Head Socket Set Screw Bolts Assortment Kit Grub Screw with Internal Hex Drive (Black): Amazon.com: Industrial & Scientific
• Drill press: Amazon.com: WEN 4206T 2.3-Amp 8-Inch 5-Speed Cast Iron Benchtop Drill Press : Everything Else

 

Edited September 30, 2022 by Elliott Reitz
typos and keyboard failure fixes

[Paulc]

I find it concerning that suppliers continue to sell a product in the knowledge they are putting people's lives at risk over making a quick buck! If a seller knowingly sells a dangerous item and the buyer suffers a serious accident as a result of the know fault,  can the buyer take legal action against the seller?

I did cancel my S22 based on this problem alone, I for one, can't be kingsongs guinea pig.

[Elliott Reitz]

3 minutes ago, Paulc said:

I find it concerning that suppliers continue to sell a product in the knowledge they are putting people's lives at risk over making a quick buck! If a seller knowingly sells a dangerous item and the buyer suffers a serious accident as a result of the know fault,  can the buyer take legal action against the seller?

I did cancel my S22 based on this problem alone, I for one, can't be kingsongs guinea pig.

I think you'd have a hard time proving the rider wasn't already taking his risks.  

PS:  Chance Hinz had a stator slip on a T4 too.  I suspect the problem is only manifesting now in wheels with >2500W of power.