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

[NErider]

Is the plastic insulation layer slipping? Or is it the interface between the pressed ring over the hub assembly slipping? 

Initially I thought it was the plastic ring, but after the "microscope vid" it looks like the pressed metal ring - to the cast hub is what slips, and the set screws lock it. 

[dycus]

Edit: double post

Edited September 24, 2022 by dycus

[dycus]

On 9/21/2022 at 4:42 PM, supercurio said:

This is a really smart idea, though I wonder if putting that screw there is shorting all the motor laminations? I don't know the exact construction, I guess if the stator is meant to butt right up to the aluminum frame, they wouldn't have the laminations exposed on the inside diameter.

If the laminations were shorted, there would be huge eddy current losses, meaning increased motor temperatures and much less power output.

Edited September 24, 2022 by dycus

[NErider]

41 minutes ago, dycus said:

This is a really smart idea, though I wonder if putting that screw there is shorting all the motor laminations? I don't know the exact construction, I guess if the stator is meant to butt right up to the aluminum frame, they wouldn't have the laminations exposed on the inside diameter.

If the laminations were shorted, there would be huge eddy current losses, meaning increased motor temperatures and much less power output.

I don't see that set screw having any effect on the electrical operation of the motor windings, laminations or performance in any way. Looks like a crude, but perfectly robust fix that is permanent with almost no downside. Possibly a minor change in balance,  but for our application,  no factor at all. 

[Elliott Reitz]

On 9/21/2022 at 7:42 PM, supercurio said:

...

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)

 

...

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.

Bravo!  A mechanical solution! 

I've induced that error 13 by attempting a tree-root climb.  The root was similar to an 8" curb going up hill.  I thought the hill would help the up-momentum climb it but I over-torqued it and it cut out.  The I was lucky it reset via power off/on.  I've done the same thing to my S18 and the only way to clear that error from S18 is to connect it to a charger for a few seconds.  

[Planemo]

5 hours ago, supercurio said:

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.

Thats exactly the method of 'pinning' I suggested as a solution a while back. The only thing I would add is that if I had gone to the bother of stripping the wheel to this stage, I would add at least another grub screw/pin, preferably two, evenly spaced at 180 deg/120 deg. If one has the suitable drill/taps then adding another 2 at the same time would take minutes relative to the stripdown/rebuild time.

[dycus]

5 hours ago, NErider said:

I don't see that set screw having any effect on the electrical operation of the motor windings, laminations or performance in any way. Looks like a crude, but perfectly robust fix that is permanent with almost no downside. Possibly a minor change in balance,  but for our application,  no factor at all. 

Motor stators (and transformers) use dozens of layers of laminated plates that are electrically insulated from each other, rather than a single solid piece of metal. This greatly reduces eddy current losses in the stator. If the laminations were all shorted together by the screw, it's still a little bit better than if the stator were one solid piece of metal, but it mostly negates the benefits of having the insulated laminations in the first place. There will be more heating in the stator and the power output will be reduced.

https://www.motioncontroltips.com/faq-why-are-dc-motor-armature-cores-made-of-laminations/

[supercurio]

Thanks @dycus for raising this concern!

Reduced power output and more heat in the stator are definitely undesirable side effects, especially since some S22 owners already get the motor close to it's maximum allowed temperature and into tiltback.

[Eucner]

1 hour ago, dycus said:

Motor stators (and transformers) use dozens of layers of laminated plates that are electrically insulated from each other, rather than a single solid piece of metal. This greatly reduces eddy current losses in the stator. If the laminations were all shorted together by the screw, it's still a little bit better than if the stator were one solid piece of metal, but it mostly negates the benefits of having the insulated laminations in the first place. There will be more heating in the stator and the power output will be reduced.

https://www.motioncontroltips.com/faq-why-are-dc-motor-armature-cores-made-of-laminations/

The set screws are installed far away from laminated armature core plates. They will not have any significant impact in Eddy currents.

[Elliott Reitz]

2 hours ago, supercurio said:

Thanks @dycus for raising this concern!

Reduced power output and more heat in the stator are definitely undesirable side effects, especially since some S22 owners already get the motor close to it's maximum allowed temperature and into tiltback.

Got any reference videos to anyone achieving that?  I've pushed my S22 pretty hard in the high 30's mph with headwinds and haven't yet seen a tiltback.  (riding over 40 changes the game, I need more time to get comfortable over 40)

[supercurio]

1 hour ago, Elliott Reitz said:

Got any reference videos to anyone achieving that?  I've pushed my S22 pretty hard in the high 30's mph with headwinds and haven't yet seen a tiltback.  (riding over 40 changes the game, I need more time to get comfortable over 40)

That would be some longer duration climbing at a speed where there's not much airflow to cool the motor, despite the open design grooves added on the side covers.

To get the motor hot, anything with high phase current (what generates heat) and low speed will do if it's sustained long enough. Anything at higher speed won't see the temp rising, due to lower phase current demands and orders of magnitude more cooling.

Someone asked a question about their high motor temps yesterday but I forgot the source.

It could be relevant on the stator slip, as several assume that the stator and its base might expand at different rates with the stator being the hottest, increasing the risk of slippage. It's a common concern in the Russian S22 riding community.

Edited September 24, 2022 by supercurio

[YourAubsome]

2 hours ago, Elliott Reitz said:

Got any reference videos to anyone achieving that?  I've pushed my S22 pretty hard in the high 30's mph with headwinds and haven't yet seen a tiltback.  (riding over 40 changes the game, I need more time to get comfortable over 40)

I overheated my motor multiple times and I only rode 100 miles before my controller broke. I can confirm that the overheat protection for the motor works (it beeps first then does tilt back). 

[EUCSideEffect]

Any tips on securing the stator in place even if it's just as a precaution?

[pedroMDK]

Afternoon! Is this the motor or the suspension making the popping noise? It doesn't sound clunky. I'm thinking suspension as I think I heard it make the pop when it was powered off. TIA for suggestions.

 

 

[NErider]

On 9/24/2022 at 4:15 PM, EUCSideEffect said:

Any tips on securing the stator in place even if it's just as a precaution?

Drill and tap it, then lock tite set screws in position. There is a post illustrating how to do it. It would hold forever then. 

Edit: While you are in there apply green lock tite bearing retaining compound to the OD of the wheel bearings also. I would NOT do the ID also, because you are essentially gluing it shut for good. 

Edited September 25, 2022 by NErider
Added info

[supercurio]

A riding buddy who got his S22 the same day as me had the first scraping sound appear today (then disappear). Following the patten of sounds with stator slippage.

He rode 2450km with zero issues.

Stairs, jumps, agressive riding: no problem until now.

It shows a S22 motor cannot be considered free of defect because it survived any amount of distance ridden.

[Beachboy]

My motor also made scrapping sound but then after checking here and there, found out the tyre was flat..LOL..

man, this thing really made my day…even KS engineers thought it was the motor..🤣🤣

Edited September 26, 2022 by Beachboy

[alcatraz]

If anyone is interested in retaining compound for bearings they're ordered like this from high strength to low strength.

638

609

641

That means, try 641 first if you're afraid to glue in your bearing permanently. If they still move around then go to a higher strength.

If you use 609/638 right away you might need a blow torch/sledge hammer to replace bearings later. Bit risky.

[UniVehje]

9 hours ago, supercurio said:

It shows a S22 motor cannot be considered free of defect because it survived any amount of distance ridden.

Clear case for recalling and replacing ALL motors manufactured before July. It’s a safety issue first but also affects the resale value. Resellers will have difficult time refusing based on the evidence so far. KS will likely try everything before agreeing. 

[daniel1234]

I am waiting for disaster with name of "Begode T4" - seems like time to buy a bearing press and table drill. It gives me hope to see that there are solutions for those issues.

Can somebody link some bearing that would fit s22 / T4 ? Since we need to take the hub apart I guess it is worth of effort to replace the bearing for a better one.

[supercurio]

Good news regarding the motor S22 motor improvements, I described the concerns raised and discussed by @dycus @Eucner @RolluS @techyiam, and the engineer's reply was too wholesome to not share 😌

 

[Eucner]

1 hour ago, supercurio said:

Good news regarding the motor S22 motor improvements, I described the concerns raised and discussed by @dycus @Eucner @RolluS @techyiam, and the engineer's reply was too wholesome to not share 😌

 

Very nice that they verified it. I can't understand how the set screw could have significantly affected eddy currents, but it is better to be sure than just deduce how it will work.

[supercurio]

1 hour ago, Eucner said:

Very nice that they verified it. I can't understand how the set screw could have significantly affected eddy currents, but it is better to be sure than just deduce how it will work.

That was in the case either drilling itself or installing a long enough screw or pin would short motor laminations.
The revised motor includes 4x steel pins (5mm diameter).

It was nice indeed to have confirmation that it does not impact motor performance since the material of the pins used was also discussed as a concern recently.

Edited September 26, 2022 by supercurio

[supercurio]

I added a few updates and corrections to the original post for what is know today, September 26 2022

[mrjuggles]

It's just amazing that these were ever sent out in the first place.  I've just requested a refund for my order from Eevees, I would definitely not feel safe riding one.