Kingsong s20 Cut out FIRE (New York)

[meepmeepmayer]

Given by the like-soft-mode behavior of the S20 that @U-Stridefelt before it died, we can assume a board capacitor was broken. So the board failing first seems likely?

Again, not an excuse for the battery to blow up, but it still happened.

[RockyTop]

1 minute ago, meepmeepmayer said:

Given by the like-soft-mode behavior of the S20 that @U-Stridefelt before it died, we can assume a board capacitor was broken. So the board failing first seems likely?

Again, not an excuse for the battery to blow up, but it still happened.

I believe you are correct. However can a fuse fix this problem? If it could it would be cheap and easy. Fuses are NOT the solution used with IGBTs. Instead a quick dropping circuit is used. I don’t think a fuse can be strong enough to hold during riding and then drop quickly enough when shorted. 
 

I am just looking at parallel solutions used in other industries. 

[supercurio]

16 minutes ago, RockyTop said:

You are too kind. I remember arm chair critics predicting the problem way in advance.

Agree on the V12, Inmotion essentially ignored the datasheet of the MOSFET. They conducted tests instead which passed and voilà good to go!
100V MOSFET failing on a 100.8V wheel. Such a surprise!

On the S20 there's a similar story at least on the BMS fuses. Tiny SMD 60A fuses rated up to 60V DC. Directly mounted on the BMS PCB, no case around them to contain arcing.
They don't seem to have done the job at ~124V DC. Shocking!

[Planemo]

14 minutes ago, meepmeepmayer said:

Given by the like-soft-mode behavior of the S20 that @U-Stridefelt before it died, we can assume a board capacitor was broken. So the board failing first seems likely?

I'm not convinced a capacitor failed, only because when one failed on my buddies MSX no softness was felt at all, it would just totally cut out at (low) random speeds. Nothing to suggest there was a problem with the wheel prior. But out of interest, has anyone looked at the specification of the S20 caps...?

[supercurio]

4 minutes ago, Planemo said:

I'm not convinced a capacitor failed, only because when one failed on my buddies MSX no softness was felt at all, it would just totally cut out at (low) random speeds. Nothing to suggest there was a problem with the wheel prior. But out of interest, has anyone looked at the specification of the S20 caps...?

Neither, I also rode (before realizing) for a few km with a busted capacitor on my 1st Sherman board and observed no difference in behavior.
Although possibly because the 24s10p battery has so much headroom that the capacitor in parallel with it doesn't need to do that much.

Edited March 30, 2022 by supercurio

[Paul A]

Would be helpful to regain trust if KS were to provide evidence by means of video:

 

Video of KS actually able to achieve an exploding/flamethrower S20.

Video of the solution/fix.

Video of the test after the fix, and the S20 not exploding.

 

If KS are not able to achieve an exploding S20, that might be troublesome.

 

[Driftcycle]

28 minutes ago, Paul A said:

 

If KS are not able to achieve an exploding S20, that might be troublesome.

 

THIS!! Facts! If KS not able to recreate, we will always have that exploding tick in the back of our mind (at home, inside a store, elevator, traffic, trails, transit etc) on if today will be the day the Kingsong goes Nuclear 😬

[Grimm10]

I have a feeling that KingSong know exactly why it's wheel blew.  It's the update that's going to make the wheel even slower off the line. 

The previous update likely pushed the capacitors to the limit to improve the lack of torque that this "powerful 126 volt" has, causing the Eagle to singe it's wings.

[Tawpie]

1 hour ago, Driftcycle said:

we will always have that exploding tick in the back of our mind (at home, inside a store, elevator, traffic, trails, transit etc) on if today will be the day the Kingsong goes Nuclear

This should always be in the back of your mind. Nevertheless, there are few things different about this fire:

1. It appears to have been caused by some sort of cascading failure that started the bottom pack on fire (clearly not acceptable)
2. Due to the metal boxes holding the battery packs, the fire involved all or nearly all of the cells because the heat was also relatively contained and the core of the fire wasn't dispersed by exploding cells. This containment ensures that basically every single cell will overheat and let all of its energy out in a very short period of time (certainly not something we want)
3. The top pack sat on top of the fire for a while, then it too caught fire (understandable, there's little that can be done about this)

We've seen plenty of wheels burn up, but this is the first EUC where the batteries were held in something that didn't melt at 300°F. The containment had a large contribution to this being more spectacular than other fires (all of the gases were forced through openings in the metal box... the hole for the wires and a breach in the side of the top battery box)

I can guarantee you that any other pack that's held in a metal box and has a cell go thermal runaway will be equally spectacular. For me anyway, the battery case may actually be a reason for me not to complete the sale on my S20—not because of brand, but because any conventional Li Ion cell can go thermal... and the protective case is ensuring that any single cell in thermal runaway will set the entire pack off. And do so basically all at once.

S20 has this problem. So does Master. So does EX20S.

Let's make the structural frame of the box out of metal, but the sides out of thermoplastic. Let the flaming missiles escape (never thought I'd say that!!!) Then we're at least not increasing the risk of having most or all of the cells in thermal runaway.

Edited March 30, 2022 by Tawpie

[meepmeepmayer]

Damn, you're right! The battery boxes seem to be a bad idea. Foil packs tend to only have a few cells burn.

10 minutes ago, Tawpie said:

S20 has this problem. So does Master. So does EX20S.

[Tawpie]

Ah shucks. I just realized my S18 has its batteries in metal boxes too. I wonder if Hero or X-Men... nah, far too ugly. I'll ride the 16X.

Edited March 30, 2022 by Tawpie

[chanman]

Can't say I'm totally convinced that the box makes things significantly worse, the cells are connected and held closely by electronics, whether they're shrink wrapped or put in a metal box, one cell burning up is liable to spread to the whole pack. Maybe some cells get to escape the pack propelled out by gasses or something instead of burning but either way wheel is totaled and fire is big.

Edited March 30, 2022 by chanman
grammar

[supercurio]

@Tawpie interesting, you describe as problematic what I saw earlier described as an asset.
The intensity was spectacular no doubt, but at the same time it was in a short amount of time. It's definitely a bad thing since it will rapidly reaches the critical state early, when you might be trying to throw the wheel out the window. But might it also be a good thing since it's directionally limited and ends quickly/quicker?

 

53 minutes ago, Grimm10 said:

I have a feeling that KingSong know exactly why its wheel blew.  It's the update that's going to make the wheel even slower off the line.
The previous update likely pushed the capacitors to the limit to improve the lack of torque that this "powerful 126 volt" has, causing the Eagle to singe it's wings.

Agree KingSong quick communication projects a "oh yeah we know - we fixed that bug a few days ago actually but didn't deploy yet: oops I guess" kind of vibe.
However the burning demo wheel was not updated with the latest firmware, reportedly increasing low-end responsiveness (would like to know how)
Then the wheel failed on hard breaking not acceleration.

I do recall however Kingsong communicating to their reviewers this:

Quote

Now let's talk about the cutouts that we've been hearing about: so this wheel is 126 volts and they are using  grade A mosfets but because the the voltage is so high there's a limit to on the current as you're accelerating from zero for the first three meters
That's what's been explained to me so for the first three meters I'd take it easy but if you're going at speed and you do want to accelerate the torque is still there it's just that because the high voltage and what the mosfets can bear if they do push out more current you could end up burning your mosfets and well you'll need a motherboard replacement.

This description mixing up voltage current, accelerating, distance is still between fuzzy and nonsensical to me, like a bunch of mumbo-jump that's lost in translation, a big misunderstanding or a really bad idea in terms of workaround.

Thanks to the power of 20/20 hindsight, it tells us at least that at the higher voltages, KingSong already had a bunch of board failures.
Interesting what we can read between the lines. Similarly to the V12 HT "more durable MOS" long before Inmotion would acknowledge a design defect.
It is a repeat here? I believe it's too early to tell this time, but let's keep it in mind as a red flag when interpreting their incoming April 1st statements.

Then comes @U-Stride joyfully slamming the brakes in repeat near full battery and way beyond max voltage as result. 🧨
Exactly what KS was trying to avoid, oops! 🔥

With timestamp:

 

Edited March 30, 2022 by supercurio

[Grimm10]

It sure would be interesting to hear Jack's opinion on the S20 now.  I bet you he's likely disappointed in Kingsong's execution of his vision on how this wheel should be performing.  I think many have, I do.  It's likely that KingSong started to cut costs by using lower specs on its components, and using cheaper parts.

[Tawpie]

3 minutes ago, supercurio said:

But might it also be a good thing since it's directionally limited and ends quickly/quicker?

Having the super hot fire not last as long is better to be sure, and once everything finished blow torching it was just plastic and rubber burning... much lower intensity so that's not as terrible. Maybe they'll have to include "point away from people and flammable objects if the battery catches on fire" in the destructions.

[Driftcycle]

24 minutes ago, Grimm10 said:

It sure would be interesting to hear Jack's opinion on the S20 now.

Pretty sure Jack is relieved he is no longer the spokesman for Kingsong anymore given this disappointment turn of events 🫣

However I'm sure he is waiting for Kingsong's response on April 1st before he shares his views which also holds weight. 

[Tawpie]

32 minutes ago, supercurio said:

@Tawpie interesting, you describe as problematic what I saw earlier described as an asset.

Hindsight right? Catches everybody, including Engineers. Especially Engineers actually.

Yes, for protecting the battery pack from impact damage, a metal box is definitely an asset. What hadn't dawned on me until I saw this fire was the unintended consequence. I'm pretty sure somebody in some design review somewhere pointed this out and the answer was "it won't start on fire and if it does, the fire won't spread as badly because it's contained. Look at the videos of GW fires spewing flaming debris everywhere. Look at how well the water logged S18s kept the fire contained to the wheel. Which is better?".

I'd bet nobody tossed one on the barbie to see what happened because they all stopped at "the pack will be destroyed and it will be very bad". I certainly went there. Exactly how it would meet its end, and how that would play on TV, likely didn't come up.

I mean in the long run, what's worse? Risk damaging the pack when the wheel cartwheels down the mountain side because you didn't afford it rigid protection? Or putting it in a protective metal box and if it does burn up, it becomes a small rocket motor? I guess my risk management hat comes down in favor of "protective box", because physically damaged cells can start (regular) fires pretty easily. But a batteries-in-a-box fire really brings home how much energy we have in our wheels.

More room for improved designs there is. Much more room.

[supercurio]

@Tawpie good points.

By the way my formulation was not that great so to clarify I didn't mean to say that I read from you that it was an asset and you changed your mind. More like I read everywhere that metallic enclosure were just better, but then seeing what happens in practice gives a better idea of the tradeoffs.

On the S20 NYC fire I also keep in mind that the packs were at close to full capacity. At 50% or 20% battery it would have been less spectacular.

I'm looking forward to an in-depth comparison of the S20 battery boxes with the EX20S.

@ray rokni @GoGeorgeGo

Edited March 31, 2022 by supercurio

[.....]

Seal 'em up nice and tight. Either they dont get damaged in a crash, or they simply become an epic explosion. None of this sissy roman candle B.S.! Metal schrapnel is always preferrable to some composite plastic anyhow!

Which is more important, affordable, or safer? Electrical density, or stablity? Where does weight and complexity of battery and management systems come into play on the list? I simply want it ALL, and maybe a self destruct button for those diehard fans...

Edited March 31, 2022 by ShanesPlanet

[Paul A]

 

[Paul A]

One viewer comment and reply from the U-Stride video posted above.

 

sby1076

1 hour ago

You should try to ride other demo wheel to prove that S20 demo wheels are all lemon...coz we got 100kg rider who ride hard like u too here but nothing happened...I still believe that wheel had issue already

 

U-Stride

11 minutes ago

 

Yeah it's highly possible

[GoGeorgeGo]

1 hour ago, supercurio said:

@Tawpie good points.

By the way my formulation was not that great so to clarify I didn't mean to say that I read from you that it was an asset and you changed your mind. More like I read everywhere that metallic enclosure were just better, but then seeing what happens in practice gives a better idea of the tradeoffs.

On the S20 NYC fire I also keep in mind that the packs were at close to full capacity. At 50% or 20% battery it would have been less spectacular.

I'm looking forward to an in-depth comparison of the S20 battery boxes with the EX20S.

@ray rokni @GoGeorgeGo

Cant say if or when i will get a chance to see an s20 anytime in the near future. But as far as the ex20s battery boxes are concerned they are by all appearances very rugged. They come sealed and weatherproofed from factory so im not going to be ripping them apart or anything. This is my personal wheel, not a demo to be torn apart and inspected. 

All i can say is they have steel brackets holding aluminum casings, and they felt solid in my hands. The one thing i did notice though is all 4 packs where designed with the wire exiting the same corner. Meaning once assembled, that two packs have wires "inside" the frame, and two packs have wires "outside" the frame. It doesnt make much of a difference, but just a little thing that i noticed when putting them on.

Edited March 31, 2022 by GoGeorgeGo

[Freeforester]

On 3/28/2022 at 6:30 PM, fryman said:

Can we get another S20 tester to test their wheel with the same riding style?

It has to be said, and I mean absolutely no disrespect, but U-stride himself admitted that he has managed to break another brand wheel (his Begode MSP HS) by the same or very similar ‘testing’ method, ie the means of applying heavy and fast pressure in order to rapidly accelerate or decelerate ( - the latter also referred to as to ‘brake’); we can infer that this test method can and will test all wheels, possibly to beyond their maximum limit.   As such, it might be an interesting exercise (in fairness to Kingsong) to see which other wheels, be they ‘performance’- or ‘sporty’-leaning (what we consider to be quick off the mark, if not outright ‘torquey’ units) are able to withstand such a test, or otherwise, although somewhere along the line the question of ‘reasonable use’ is likely to become a consideration, eg would we consider testing a car or other vehicle in a similar way, or would there be any merit in discouraging such a ‘to-the-limit-and-beyond’ riding style?    I don’t personally think it would be great to recommend others stress test their devices in such a manner, though I have an open mind about whether the community feel that so doing represents ‘fair’ or ‘legitimate’ use. 
 

I note it as has already been stated in the thread that generally speaking, it is accepted that it is highly risky to induce such rapid deceleration/‘braking’ tests on a full or near full charged battery, which I seem to recall being the state of the MSP HS which was also broken by a similar type of ‘full-force’ test. This is in no way seeking to justify the ensuing fire, which was a most sobering reminder of how badly things can turn out when a chain of events don’t turn out as may have reasonably been anticipated.    I’m halfway thinking it may have been  in the back of U-stride’s mind that the test would - IF PASSED - demonstrate that the S20 was indeed built more strongly or designed more thoroughly than the Begode wheels, as their hitherto reputation has been implied on other occasions, but - if failed - would result in not much more than a broken motherboard or popped capacitor therein, but little else by way of damage - though there seems little point in offering to replace the motherboard when there is nothing to salvage from the rest of the unit!  
 

I guess where I’m gong with this preamble is whether there is any merit in consideration being given to our generally accepted recommended riding techniques, or is it always going to be the fault of whatever manufacturer - irrespective of which- as and when it is the ‘means of use/riding style/technique’, be that felt to be ‘fair’, ‘legitimate’ or ‘normal’ which causes the wheel to break down.    I’m thinking too of the Marty/Speedyfeet “School of riding” as being quite different from that of either U-stride, or some of the “New York” School of charging-headlong-forth” style-riders. Had this outcome happened where Marty or Ian were the rider, then I would have been deeply concerned and surprised, but when the wheel (already known to be not really designed to be, and already restricted for safety reasons when going for a full-send from a standing start) decides to blow its top when similarly ‘challenged’ in a ‘full-receive’ into a standing stop, then frankly I’m personally less surprised.
 

Again, the ensuing blaze was not the expected outcome, and in many ways it is a good thing that this aspect has been uncovered now, pre-general release, though it surely represents a high likelihood of a yet further delayed eventual release date, which prospective buyers (of which I am not personally among) must be both legitimately satisfied, and yet not entirely happy about.

 

The general recommendation that we ‘don’t try this at home with our own wheel’ might well be heeded.

Edited March 31, 2022 by Freeforester

[Rawnei]

6 hours ago, Grimm10 said:

I have a feeling that KingSong know exactly why it's wheel blew.  It's the update that's going to make the wheel even slower off the line. 

The previous update likely pushed the capacitors to the limit to improve the lack of torque that this "powerful 126 volt" has, causing the Eagle to singe it's wings.

I see this narrative pushed over and over, the wheel wasn't even on latest FW version as confirmed by the owner and it's obvious that failsafes that need to be there regardless of performance didn't work, so can we please not do this?

[Tawpie]

35 minutes ago, Freeforester said:

It has to be said, and I mean absolutely no disrespect, but U-stride himself admitted that he has managed to break another brand wheel (his Begode MSP HS) by the same or very similar ‘testing’ method, ie the means of applying heavy and fast pressure in order to rapidly accelerate or decelerate ( - the latter also referred to as to ‘brake’); we can infer that this test method can and will test all wheels, possibly to beyond their maximum limit.   As such, it might be an interesting exercise (in fairness to Kingsong) to see which other wheels, be they ‘performance’- or ‘sporty’-leaning (what we consider to be quick off the mark, if not outright ‘torquey’ units) are able to withstand such a test, or otherwise, although somewhere along the line the question of ‘reasonable use’ is likely to become a consideration, eg would we consider testing a car or other vehicle in a similar way, or would there be any merit in discouraging such a ‘to-the-limit-and-beyond’ riding style?    I don’t personally think it would be great to recommend others stress test their devices in such a manner, though I have an open mind about whether the community feel that so doing represents ‘fair’ or ‘legitimate’ use. 
 

I note it as has already been stated in the thread that generally speaking, it is accepted that it is highly risky to induce such rapid deceleration/‘braking’ tests on a full or near full charged battery, which I seem to recall being the state of the MSP HS which was also broken by a similar type of ‘full-force’ test. This is in no way seeking to justify the ensuing fire, which was a most sobering reminder of how badly things can turn out when a chain of events don’t turn out as may have reasonably been anticipated.    I’m halfway thinking it may have been  in the back of U-stride’s mind that the test would - IF PASSED - demonstrate that the S20 was indeed built more strongly or designed more thoroughly than the Begode wheels, as their hitherto reputation has been implied on other occasions, but - if failed - would result in not much more than a broken motherboard or popped capacitor therein, but little else by way of damage - though there seems little point in offering to replace the motherboard when there is nothing to salvage from the rest of the unit!  
 

I guess where I’m gong with this preamble is whether there is any merit in consideration being given to our generally accepted recommended riding techniques, or is it always going to be the fault of whatever manufacturer - irrespective of which- as and when it is the ‘means of use/riding style/technique’, be that felt to be ‘fair’, ‘legitimate’ or ‘normal’ which causes the wheel to break down.    I’m thinking too of the Marty/Speedyfeet “School of riding” as being quite different from that of either U-stride, or some of the “New York” School of charging-headlong-forth” style-riders. Had this outcome happened where Marty or Ian were the rider, then I would have been deeply concerned and surprised, but when the wheel (already known to be not really designed to be, and already restricted for safety reasons when going for a full-send from a standing start) decides to blow its top when similarly ‘challenged’ in a ‘full-receive’ into a standing stop, then frankly I’m personally less surprised.
 

Again, the ensuing blaze was not the expected outcome, and in many ways it is a good thing that this aspect has been uncovered now, pre-general release, though it surely represents a high likelihood of a yet further delayed eventual release date, which prospective buyers (of which I am not personally among) must be both legitimately satisfied, and yet not entirely happy about.

 

The general recommendation that we ‘don’t try this at home with our own wheel’ might well be heeded.

Thank you for your post @Freeforester.

I see a lot of value in the kind of "testing" the NYC YT crew do... they push well past where I'm going to go with any of my wheels. I'm not nearly that brave, or skilled, and don't heal fast anymore. I don't need my wheel to do what they need theirs to do. Nevertheless, having seen the wheel hammer its way through the pothole filled streets of NYC at 35 mph, in the hands of riders that can *really* ride that way gives me a higher level of confidence that my poking around on blue trails and forest roads shouldn't end with me walking or carrying the wheel home. Because I'll never ask it to do what they ask. But I'm glad they do push the limits, and am grateful for their enthusiasm... it does provide a service to me.

My only problem is what happened after U-Stride was so unceremoniously dumped... I'd really rather not start the next big wildfire because a part failed. I have zero idea why the 'system' allowed the cells to hit thermal runaway—it could be that "fix bug" means "turn the BMS safeties back on cuz they were turned off (and that developer is now assigned to licking the packing tape before it's put on the boxes)". It's probably something else though, and I expect we'll see an inline fuse because it's highly visible, covers a lot of bases, and makes sense to us lowly consumers. I hope that's enough.