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


supercurio

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  • supercurio changed the title to King Song S22 motor stator slippage issue: more severe than expected

@UniVehje yes tough question, I guess there's several scenarios.

  • QC problem leading to the stator slippage due to something like glue missing on some motors (wild uneducated guess), or bad quality materials that made it in the supply.
  • Molds for parts with the wrong tolerances, so what's expected to fit and hold slips instead, on all units until the mold was fixed.
  • Only one of the molds had the wrong tolerances, so a set % of motors are defective until it was removed from production.
Edited by supercurio
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@Tawpie eWheels is not part of the group chatting together on a regular basis, but yes I gave @Jason McNeil a heads up as soon as we made the discovery, and sent him the completed draft yesterday.
He confirmed that he's in now in touch with KS on this specific issue. I hope eWheels shipment comes with motors with the fix for the stator slippage, but I'm not sure.

To be continued.

Edited by supercurio
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@Goonman indeed, before posting I searched for this problem being documented elsewhere but was not able to find anything. Not really the kind of innovation we were hoping for.

By the way, if anybody has a better name for this I'm all ears - I had to come up with something.

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Appreciated @Rich Sam, glad you enjoyed the read!

From what I gathered, the S22s in Seattle broke from separate issues: the mainboard failing without the phase wires being physically shorted.
There's no shortage of concurrent issues on the S22 for now.

Edited by supercurio
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If they offered some official self repair videos/kits maybe someone would start to offer a service on the same continent, and move towards becoming an authorized service place.

I bet some buyers or resellers would rather fix it themselves than send it all back.

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@alcatraz it might be possible indeed to locally repair all motors before they destroy themselves 

I just watched this video which highlights how the stator is attached to its base. And it's with glue indeed, but stators can also remain in place on their base thanks to a friction fit.

I still don't know if the S22 motor stator slips because of insufficient glue or friction fit, but it has to be one or the other.
In case removing the stator of these dimensions doesn't require impractical forces which would damage it in the processes then yes they could be repaired, essentially by glueing the stator to its base correctly.

 

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@supercurio Did you have pictures from the other side of the motor? There's the black plastic ring-thing that has tabs going under each coil, which has moved out of place with the stator. Is it that plastic that tries to hold it in place or why does it have those other wider tabs that extend inwards towards the center?

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Holy moly, this is much worse than the cutout issue of the Inmotion V12. Almost 300 years of building electric motors and we STILL havent figured it out?

 

EDIT: if the stator really held on the hub base by glue and/or friction only that is really poor engineering. I have no engineering qualifications whatsoever, just a bunch of experience from building RC cars and planes but it is obviuos to me that there should have been another, mechanical means of holding the stator in place, like small, intermeshing teeth like on gears, or a couple of large "nubs" on the inside of the hole in the stator and corresponding "holes" in the base. This would have prevented any slippage, and with cast parts it would have had no additional cost. Or even just a couple of TIG weld spots, its not like you have to separate stator and hub base on a daily basis.

Edited by mhpr262
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@mhpr262 it sounds like my post make its point convincingly, however I don't think this specific problem is as bad as the V12 original boards cutouts. Or at least, it's different, mainly:

In most or at least some of the cases, there will be warning signs with motor scraping sounds. With the V12, there were no warnings whatsoever.
Although these signs can be missed, or maybe be absent in some case if the failure is more sudden like during a hard braking or bad landing instance.

There were scraping sounds in all document cases so far which is a positive.

The negative is that the S22 also has an issue with boards dying suddenly, so both compounded is not great.

 

2 hours ago, mhpr262 said:

EDIT: if the stator really held on the hub base by glue and/or friction only that is really poor engineering. I have no engineering qualifications whatsoever, just a bunch of experience from building RC cars and planes but it is obviuos to me that there should have been another, mechanical means of holding the stator in place, like small, intermeshing teeth like on gears, or a couple of large "nubs" on the inside of the hole in the stator and corresponding "holes" in the base. This would have prevented any slippage, and with cast parts it would have had no additional cost. Or even just a couple of TIG weld spots, its not like you have to separate stator and hub base on a daily basis.

Maybe someone building EV motors can share knowledge on how it is typically (successfully done) to prevent stator slippage.
It would be nice to know, especially to check the validity of the solution adopted in the fixed motors and be confident it doesn't happen again.

Edited by supercurio
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Another case reported on the reddit thread, reseller: EUCO, country: US, new rider (first wheel)

Notable that the cutout can happen only a couple seconds after the louder rubbing sound appears.

It's because the louder rubbing sound are due to the phase wires rubbing on the side covers. When that happens it's quickly game over.

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