Inmotion V12 HT board: "More durable MOS"

[supercurio]

Electronics design problem with the V12

The 2nd batch of Inmotion V12 100.8V wheel highlighted the inherent fragility of its board design due to the choice of Infineon IPP023N10N5 100V-rated MOSFET.

12x IPP023N10N5, source: Wrong Way InMotion V12 Quality Check - Teardown video published Nov 4, 2021

 

As indicated in the specsheet listed, the figure of 100V is called "Drain-source breakdown voltage"
The definition and an explanation of this term can be read here:

Quote

This the region where the transistor receives too much voltage across its drain-source terminal, which causes the drain-source terminal to break down, which makes the drain current, ID, drastically increase.

Then the IPP023N10N5 maximum "Avalanche energy, single pulse" is specified in mJ. Anything beyond that introduce immediate permanent damage.

Above the breakdown voltage, we know that drain current can't be limited anymore which will increase the energy dissipated and permanently damage (short) the MOSFET.
For a wheel, a single shorted MOFET leads to a cut-out, and likely unavoidable crash.

This is what happened to a number of owners tracked in this thread, as the supply for these MOSFET was not as high as earlier and Inmotion didn't test the components or the final result.
Some exceptions in this pattern appeared,with 13% of cutouts not destroying the component despite throwing the rider off, since a MOSFET will behave unpredictably before failing.

A stress test has been improvised for owners and distributors to test the wheel, and now customers are trying to figure out if their wheel is safe or not even if it passed the test, since the design itself violates the main motor control component specifications.

The uncertainty is fueled by the the fact that although MOSFETs might not completely fail when used above their specification, which is the V12 normal state of things, the components will experience accelerated degradation.

How fast the degradation of a wheel passing the proposed stress test will lead to failure is anyone's guess, and there is no way to determine this than sacrificial long-term testing.
It depend on the capacity of each individual MOSFET to operate beyond capacity without failing, varying from one unit to the other.

 

Introducing the V12 HT

Following the beginning of cut-out reports, Inmotion announced a new wheel, a High Torque variant of the High Speed original V12, on December 25.

 

All that looks good, however I would like to point your attention to this part of the brochure in particular:

Yep: More duable MOS

Meanwhile Ecodrift alerted Inmotion in June 2021

Quote

This is the Infineon IPP023N10N5 . These are the same transistors found on the V11 and V10F. Everything is fine, but V12 has a higher voltage. And the nominal value of 100V looks very suspicious here. Will the field workers withstand the voltage, say, 110V during sudden braking? We really hope that Inmotion has calculated all this.

Narrator voice: "Inmotion did not"

 

Cutouts were reported to Inmotion by customers from December 3 or earlier.

In short, Inmotion was warned 6 months ago about using the wrong MOSFETs. In December, a pattern of cutouts and crashes emerged, with some riders experiencing severe injury and hefty financial cost.

Before acknowledging officially the ongoing crisis on December 31 with a post from @Cecily Inmotion, knew about the design problem and its dire consequences on the reliability of their product. Hence, they decided to upgrade the component for the V12 HT already as seen in Chinese social media for a couple weeks before its announcement.

While writing the V12 HT brochure, marketing teams asked in the company "So how is it different from the current V12?"
To that, engineering must have replied: "Well the MOSFETs are more durable"
Also meaning: because they're not durable on the V12, a few of them burning up and we know they won't last.

 

What Inmotion is expected to do onwards

Inmotion knows that V12 boards are not durable.
Even if the wheels pass a synthetic stress test today, their main component will fail early because used beyond its specifications.

It is easy to predict that all V12 models, High Speed & High Torque will use the board revision introduced for the HT version, which allows to deliver 23% more power, therefore has at least as much more margin before failing under stress.

 

Recall and upgrade

Some distributors, like eWheels mentioned a potential recall before the stress test became the recommendation.

Given all V12 built so far shipped with the wrong components to drive the motor reliably - now or over time, the clear approach to remedy this harmful blunder is to replace all V12 boards with V12 HT board hardware and its upgraded "More durable MOS"

Without this guarantee, there's a significant risk that all V12 would die when ridden, unless they becomes obsolete before that.
Wether it'll be when you ride it, your friend, your loved one, or its next owner is hard to tell.

Edited January 6, 2022 by supercurio
minor rephrasing

[ESB]

I'm going to trade out the v12 for an 18XL. Older and slower and with less features but I won't have to worry about reliability or check forums frequently. I'll happily re-evaluate v12 in 9-12 months.

Inmotion really messed up their reputation for safe and reliable wheels in my eyes. Hope to see them improve quickly.

[Paradox]

1 minute ago, ESB said:

Inmotion really messed up their reputation for safe and reliable wheels in my eyes

Maybe they can spin off the V12 under a new brand name... InMoBegode

[nosamplesplease]

16 minutes ago, Paradox said:

Maybe they can spin off the V12 under a new brand name... InMoBegode

We can laugh about this, but reputation is about how you handle a mistake rather than never having one.

Anyone including companies, that "have never made a mistake" are full of shit.

 

Lets try and be kind and objective. 

[ESB]

43 minutes ago, nosamplesplease said:

We can laugh about this, but reputation is about how you handle a mistake rather than never having one.

Anyone including companies, that "have never made a mistake" are full of shit.

 

Lets try and be kind and objective. 

very true! Despite my frustration I have to say that I've been impressed with the support I've gotten from Inmotion (had a firmware brick issue a couple months ago). Everyone I spoke with was nice, prompt, curteous and clearly proud of their work. I'm sure they're frustrated with the mosfet issue. I just wish there was a more firm response to those saying that there is an inherent design flaw with using 100v mosfets on a 100.8v wheel.

[Khazik]

1 hour ago, supercurio said:

Anything beyond that introduce immediate permanent damage.

From my layman's understanding, performing the spin test has introduced "immediate permanent damage" since the MOSFET's aren't up to spec in the first place; if your wheel passed (like mine did the first few times), the 'sooner or later' fail date becomes more 'sooner' than later. 

 

1 hour ago, supercurio said:

How fast the degradation of a wheel passing the proposed stress test will lead to failure is anyone's guess, and there is no way to determine this than sacrificial long-term testing.

100%. My wheel passed a few tests, but something just didn't feel right w/me. I had a nagging feeling I just had to do it one more time - failed. 

 

This is a really good, and pretty damning write-up. 

[Paul g]

Thank you @supercurio for pointing out the truth with so much accuracy. InMotion way of handling the situation got absolutely ridiculous. Instead of admitting their fault and offering costumers a replacement board with proper mosfets, they beat the bush instead. They even blame Infineon for faulty or unreliable products. That is even more ridiculous that said handling. For what I know InMotion Technology Co. Ltd. has never received ISO 9001:2015 Certification, nor any TUV Certification. Infineon, on the other hand did: 

InMotion wants to find a scapegoat and they also want their costumers to pay the price for their wrongdoing instead of admitting they took a wrong decision and offering to remedy the situation by replacing faulty designed control boards with proper designed ones. The worst thing is that their costumers will bear all the cost: cut outs and injuries, or possibility of death, in case of cut out in traffic among cars or at high speeds, when you can hit your head in the crash. This situation is unacceptable, and InMotion should replace the faulty boards at their cost. I encourage you to enter their site and write InMotion to do what is fair in the Chat with InMotion pop up and on their Contact page as if your life and health depends on it, because it does: https://www.inmotionworld.com/

 

 

[The Brahan Seer]

3 hours ago, supercurio said:

Before acknowledging officially the ongoing crisis on December 31 with a post from @Cecily Inmotion, knew about the design problem and its dire consequences on the reliability of their product. Hence, they decided to upgrade the component for the V12 HT already as seen in Chinese social media for a couple weeks before its announcement.

While writing the V12 HT brochure, marketing teams asked in the company "So how is it different from the current V12?"
To that, engineering must have replied: "Well the MOSFETs are more durable"
Also meaning: because they're not durable on the V12, a few of them burning up and we know they won't last.

 

 

There is a lot of assumptions here. How do you know they didn't just upgrade the MOSFET's on the V12 HT because of the uprated motor? 

So the MOSFET's are more durable compared to the standard ones.  It doesn't mean they are deliberately hiding anything.

Inmotion would have far too much to lose to try and pull the wool over the eyes of its customers. 

 

[supercurio]

2 hours ago, The Brahan Seer said:

There is a lot of assumptions here. How do you know they didn't just upgrade the MOSFET's on the V12 HT because of the uprated motor? 

So the MOSFET's are more durable compared to the standard ones.  It doesn't mean they are deliberately hiding anything.

Inmotion would have far too much to lose to try and pull the wool over the eyes of its customers.

Yes fair comment.

I agree there's some reading between the lines, but it's based on analyzing the whole chain of events from the perspective of the manufacturer, the system of incentives in place as well as what came out candidly in their own statements.

The key IMO here is that okay V12 HT board can deliver more power, 23% in their own material. More power, bigger MOSFETs, makes sense.

However what doesn't make sense is given the specified power for each model, the new board should not have "More durable MOS". V12 should have durable MOS. V12 HT should have durable MOS. If V12 HT has "More durable MOS" it automatically implies that V12 MOS lack durability.

That's why I imagined this little story of the marketing team asking around what they could add to their brochure, because it's usually what happens when you announce a new product and create marketing materials for it (unless you completely make stuff up, which is also a possibility)

It's like you'd say that the Monster Pro has more durable MOS than the Kingsong 14D. Well that's a bit of an odd statement isn't it, unless you know about flaws affecting the 14D MOS.

Any non-defective MOSFET will be "durable" if used within its specifications + an extra margin on top (the industry standard). Inmotion missed both on the V12.

 

3 hours ago, Khazik said:

From my layman's understanding, performing the spin test has introduced "immediate permanent damage" since the MOSFET's aren't up to spec in the first place; if your wheel passed (like mine did the first few times), the 'sooner or later' fail date becomes more 'sooner' than later. 

 

100%. My wheel passed a few tests, but something just didn't feel right w/me. I had a nagging feeling I just had to do it one more time - failed. 

I feel the same:

Initially I thought maybe if I run the stress test before every ride, then I know that the MOSFETs are still good.

But wouldn't the stress test accelerate damage every time, therefore increasing the risk for that ride? Knowing that the hardware is already used beyond capacity and that several people who cutout and crash had a blast on the previous fast ride, and their wheel died on the next chill one.

It all seems like a bad idea, kind of entering Darwin Awards voluntarily knowing that the hardware design is faulty no matter what.

Edited January 6, 2022 by supercurio

[mrelwood]

First, nobody can disagree that the situation is really bad, and would harm Inmotion’s reputation no matter what the reason for the failures were, and no matter how they would handle the situation. Thus it’s no surprise that it will create emotions, in some people more than in others. And I feel terribly bad for every single one who have hurt themselves because of this, and even for those who are forced to refrain from riding because of this.

 But I have a habit of trusting working professionals in any decision making or especially assessing the validity of any circuit design on any product. I have repaired guitar amps and other musical gear as a side job for over a decade. Yet I will never even give an assumption of being able to assess whether a mosfet choice in an EUC or even in a guitar amp is the right one or not. I don’t quite see how you can.

You being so sure about a large safety oriented EUC/PLEV manufacturer making a mistake so obvious that random end users and discussion forum members are able to reliably point it out doesn’t sit right with me. We’re talking about a manufacturer who has designed and sold possibly over 100000 vehicles with the same basic motor controller principle. That’s a hundred times more than I have posted on this forum. If only they had asked the right forum member to do the final check on the circuits, right?

8 hours ago, supercurio said:

I agree there's some reading between the lines, but it's based on analyzing the whole chain of events from the perspective of the manufacturer, the system of incentives in place as well as what came out candidly in their own statements.

That’s a bit thick isn’t it? You don’t have any of the countless crucial pieces of information required to know anything about the manufacturer’s perspective. “Some” reading between the lines is clearly an understatement.

 

8 hours ago, supercurio said:

If V12 HT has "More durable MOS" it automatically implies that V12 MOS lack durability.

I know you’re much smarter than this so it’s probably a language barrier. Basic lesson in logic: Me being taller than my brother doesn’t mean or imply in any way that my brother weren’t very tall as well. Being durable or not is not a black and white distinction. Some things can always be more durable than others, and the secondmost durable thing is usually still pretty darn durable.

 

8 hours ago, supercurio said:

…create marketing materials for it (unless you completely make stuff up, which is also a possibility)

That is indeed quite fitting…

I have noticed that you have been one of the most vocal participant in the recent V12 discussions. It’s clear that you take the issue strongly. What can happen though is that seeing the forest from the trees becomes increasingly more difficult as you keep strengthening your beliefs. That still doesn’t make it a fact though.

 

8 hours ago, supercurio said:

knowing that the hardware design is faulty no matter what.

If I’d ask you how you know that, you would probably point me to evidence of wheels that have failed. But if I’d ask the same from an electronics engineer specializing in BLDC motor controllers, he’d be able to explain in detail how the system works and why exactly the design is faulty, included with calculations. Do you understand the difference?

 

 Could you be right in that the company we have learned to trust the most all of a sudden no longer understands the meaning of “voltage”, decide to create a product designed to fail, and they just pull out testing instructions from their hats, hoping that the western fools would yet again be fooled? I guess you could. But it all just sounds so extremely improbable. I’d rather ask someone who knows about the matter. And I don’t mean someone who has read about the cutouts. I mean someone who actually knows the circuit diagram, inside company policies, Inmotion engineer hiring requirements, and so on.

Edited January 7, 2022 by mrelwood

[mhpr262]

I'd bet a month's wages that the engineers warned about using those MOSFETs, but the bean counters overruled them. Inmotion screwed up here in a big way.  They always had a reputation for building , well made, reliable and durable wheels. That was their biggest asset, and they threw it away for some short term profit. A big disappointment.

[Chriull]

1 hour ago, mrelwood said:

I’d rather ask someone who knows

I'd guess to find he real reason/cause is not the primary cause. Many seem frustrated and disappointed - having a v12 bought/ in preorder or wanting to buy one. Because inmotion delivers quality and is safe - and then reports of random cut outs/fried mosfets come up...

So the longer this is not solved tge more rumours will evolve and the unhappier the customers will become and "pressure build up"...

8 minutes ago, mhpr262 said:

That was their biggest asset, and they threw it away for some short term profit. A big disappointment.

No matter what caused these cutouts - Time is ticking and decreasing reputation. Imho...

If this is solved satisfactory everything will be fine again. Hopefully. I keep my fingers crossed.

Like with the ?V10 sealing kit?.

[Planemo]

Nothing wrong with Infinion FET's (assuming genuine and used within their specs). They are reputable, reliable and I have used 1000's of them with repeatable results. I know people aren't knocking Infinion per se here, but just thought I'd throw that in.

As has been said, when a FET does fail it can be unpredictable. They are not always a fail/non fail component. This is why I shudder at the stress test posted. A FET can get damaged without failing. A bit like a capacitor can age with heat and reduce it's integrity but not fail immediately.

There is no way I would use the stress test as confirmation that the FET's are OK long term.

As a result, the inconclusive and rather wafty stress test should be scrapped, and Inmotion should be sending out improved boards to ALL V12 owners, leaving the choice of labour/fitting to the owner or dealer.

It is  a great shame, Inmotion have always been right at the top for build quality IMO and I have a lot of respect for them, but crap happens as we all know. All will be good (in my view) if they just do the right thing and replace all known affected boards.

[mhpr262]

At least this issue has appeared relatively early in the production run, not just when the overloaded FETs fail prematurely from aging - two or three years from now and with thousands more wheels sold.

[supercurio]

6 hours ago, mrelwood said:

First, nobody can disagree that the situation is really bad, and would harm Inmotion’s reputation no matter what the reason for the failures were, and no matter how they would handle the situation. Thus it’s no surprise that it will create emotions, in some people more than in others. And I feel terribly bad for every single one who have hurt themselves because of this, and even for those who are forced to refrain from riding because of this.

No doubt we all feel bad about this, we all care about everyone being safe.
Since there is more demand than availability, I know if I cancel my order someone else will get the wheel, so the solution goes beyond individual responsibility.

6 hours ago, mrelwood said:

But I have a habit of trusting working professionals in any decision making or especially assessing the validity of any circuit design on any product. I have repaired guitar amps and other musical gear as a side job for over a decade. Yet I will never even give an assumption of being able to assess whether a mosfet choice in an EUC or even in a guitar amp is the right one or not. I don’t quite see how you can.

As developed in the original post: Inmotion was warned by distributors -who also are working professionals- more than 6 months ago. Warnings were ignored.
Trust needs to be earned, it is not an absolute thing, it's much more fluid than that, and it is complex at the scale of an organisation like a whole company where each individual can make mistake.

6 hours ago, mrelwood said:

You being so sure about a large safety oriented EUC/PLEV manufacturer making a mistake so obvious that random end users and discussion forum members are able to reliably point it out doesn’t sit right with me. We’re talking about a manufacturer who has designed and sold possibly over 100000 vehicles with the same basic motor controller principle. That’s a hundred times more than I have posted on this forum. If only they had asked the right forum member to do the final check on the circuits, right?

Is your point: They built many reliable wheels, therefore all the wheels they build now and in the future are reliable as well?

6 hours ago, mrelwood said:

I know you’re much smarter than this so it’s probably a language barrier. Basic lesson in logic: Me being taller than my brother doesn’t mean or imply in any way that my brother weren’t very tall as well. Being durable or not is not a black and white distinction. Some things can always be more durable than others, and the secondmost durable thing is usually still pretty darn durable.

Invalid comparison IMO:

Using a component within its specification allows it to be durable.
Using a component beyond its specification will make it not durable.

Sure, nothing is 100% durable until the end of the universe, but you cannot compare with a linear scale of people being different height.

6 hours ago, mrelwood said:

That is indeed quite fitting…

I have noticed that you have been one of the most vocal participant in the recent V12 discussions. It’s clear that you take the issue strongly. What can happen though is that seeing the forest from the trees becomes increasingly more difficult as you keep strengthening your beliefs. That still doesn’t make it a fact though.

If I’d ask you how you know that, you would probably point me to evidence of wheels that have failed. But if I’d ask the same from an electronics engineer specializing in BLDC motor controllers, he’d be able to explain in detail how the system works and why exactly the design is faulty, included with calculations. Do you understand the difference?

 Could you be right in that the company we have learned to trust the most all of a sudden no longer understands the meaning of “voltage”, decide to create a product designed to fail, and they just pull out testing instructions from their hats, hoping that the western fools would yet again be fooled? I guess you could. But it all just sounds so extremely improbable. I’d rather ask someone who knows about the matter. And I don’t mean someone who has read about the cutouts. I mean someone who actually knows the circuit diagram, inside company policies, Inmotion engineer hiring requirements, and so on.

At least one member here, who commented on the matter appears to have significant experience designing circuit boards, hi @Tawpie
After reading everyone knowledgeable's posts in the related threads, you will find each describe the design as faulty.

None of us need to use as evidence the wheels that already failed: everything is here in the datasheet already, linked at the top of the first post.

Drain-source breakdown voltage:
Minimum: 100V
Typical: -
Max: -

So what does this mean, according to the MOSFET manufacturer?
It means that the typical or maximum limits of where this component start failing are unspecified.
Any number of units might behave as desired when a bump creates sends a 115 V spike as motor EMF. Tested 200 Wheels, all good, so is it the right component?

No, because Infineon only guarantees this minimum of working correctly up to 100V.
A MOSFET with breakdown voltage of 100.0000V is within specification, despite it might make the V12 self-balancing algorithm fail on a bump due to the wrong amount of current being sent to the motor, or burn the component.

I am certainly not an electronics engineer with years of experience designing BLDC controllers, but I learned the basics of how a controller works, and have years of experience reading and implementing datasheets. Frankly, it's not that hard to break it down in this instance.

I could be wrong but in that case, is there any evidence that the MOSFETs are not directly exposed to the battery and back-EMF voltage and current? If not, please point out which components are. If they exist, they would need be connected to the heatsink and easy to identify.

These elusive components would be quite strong, since the stress test make 25% of the MOSFETs fail at the moment and none of them.

 

Regarding Inmotion handling now, let's take note of what they asked @rolis to kindly include in the Q&A in the test failure tracker

"Nominal values for components are relatively conservative"
I mean...

 

Anyway @mrelwood, my point with this thread is not to pin down Inmotion for wrongdoing or anything like that.

My goal is to pressure them to provide replacement boards using components within their specification so they have a chance to operate reliably and keep our rider community safe.
And that board seems to be designed already for the V12 HT variant.

The board looks very similar and has good chances of being a compatible retrofit, so there might be a solution right here.

Edited January 7, 2022 by supercurio

[rolis]

I would just like to thank you @supercurio for creating this topic. You have perfectly put in words what I was thinking this whole time and in a way I would never be able to.

It has been mentioned that Inmotion is  searching for a scapegoat. This can be confirmed by what Inmotion has sent a dealer (which I would like to keep private) as a reason for their wheels failing and comparing it to the facts of the matter:

Quote

So far they said that the issue came from the change of the MOSFET provider for their production. The defective ones will have to be replaced and they will probably take measures to fix the problem during the production of the next batches. 
That's all we know so far.

Change of MOSFET provider? From my knowledge they have been using the same Infineon FETs on lower end wheels in the past.

I mean that's the same as if one would say: "I bought this laptop from another dealer, that's why it is faulty" Despite being the same macbook from the same facotry.

 

The way inmotion is handling things right now is one of the reasons I have cancelled my order for the v12. I know that there are a lot of people in line for this wheel and somebody else will buy it, but action has to start somewhere.

Edited January 7, 2022 by rolis

[RagingGrandpa]

6 hours ago, mrelwood said:

talking about a manufacturer who has designed and sold possibly over 100000 vehicles with the same basic motor controller principle

It's a corporation making a product.

A scenario such as below seems completely plausible:

Employee #1: "This 100V component will go outside its spec"
Employee #2: "Nah only very rarely."
1: "But it should never!"
2: "That spec is conservative. Go test and see if it actually works."
1: "Ok I did a test."
2: "Did it fail?"
1: "No... but we only built 2 of them"
2: "What do you recommend?"
1: "Change to this other 120V component"
2: "The one you want has a 52wk lead time; we need to ship in 12wk. We already have the 100V part in the factory, and it passed your test. Ship it."

Nothing dishonest in that example.

(Dishonesty would be "the test failed!" but they ship anyway... I doubt it.)
 

Edited January 7, 2022 by RagingGrandpa

[supercurio]

@rolis happy it makes sense to you too.

Initially I found the argument of change in MOSFET production quality believable, like if fakes made their way into the supply chain and Inmotion was an unlucky causality.

It changed when the cutout list and furthermore, your test list highlighted that a number of 1st batch wheels failed just as well.

@RagingGrandpa agree it's speculation, but it sounds plausible.

Maybe they even thought it was wiser to use a known part that served them well in the past than a different one unproven to them, and it backfired.

 

Either way, with enough unlucky "testers" out here we know they didn't pick the right components, and it's time to move on to different ones instead of relying on golden samples of a 100V one.

Edited January 7, 2022 by supercurio

[mrelwood]

1 hour ago, rolis said:

Change of MOSFET provider?

Unfortunately mosfets are not MacBooks, and while it sounds wild, things like the provider can make an actual difference. Even I know that much.

Electron tubes/valves are an overly extreme example, but I’ll say it anyway. Even the most modern manufacturing processes yield tubes that vary significantly in two crucial values. There are only a few tube factories in the world, but there are many tube brands.

What the brands do is they buy truckloads of tubes, let them run for a while, and measure each tube so they can be sold in pairs and sets of 4 that match well. The ones that don’t, are either sold to a brand that sells cheaper tubes, or simply relabeled and sold as a different brand.

 What some distributors do is they buy a large batch and re-measure them themselves, and if they do it well, they can even create a fame for selling good tubes. But even they sell the cheaper tubes from the same exact factory, same exact production line, same production batch.

I don’t know how large the variation is in power mosfets in general, but at least the small Fet J201 biases extremely differently from one unit to the next, within the same batch, all the way to not functioning properly if swapped to another in-spec unit. And even if they are properly biased or the biasing were automatic, two identical products can sound slightly different.

 That’s the world of modern electronics that I know of. Nothing to do with identically behaving MacBooks, which wouldn’t surprise me if the relatively high price were partially explained with simply tighter product tolerances, ie. more scrap units.

[mrelwood]

 

2 hours ago, supercurio said:

Trust needs to be earned, it is not an absolute thing, it's much more fluid than that, and it is complex at the scale of an organisation like a whole company where each individual can make mistake.

I’m sure it is. I do wonder though that if they can simply decide to use a wrong component for not having to wait, how has the original trust for a safety oriented brand been able to form? That they could’ve done things like that many times before, but their “luck” simply ran out this time? All I have to go for is my reasoning, and it considers the scenario more improbable than probable.

2 hours ago, supercurio said:

Is your point: They built many reliable wheels, therefore all the wheels they build now and in the future are reliable as well?

Absolutely not! But considering that numerous forum members have painted blame on various EUC manufacturers many times before, and disregarding the ones related to GW, I think they have been mostly in the wrong. That doesn’t mean that they will always be wrong, but comparing the probabilities of a self acclaimed alarmist and an experienced and reputable company, it’s pretty obvious where one should place the bets.

2 hours ago, supercurio said:

Using a component within its specification allows it to be durable.

How durable?

2 hours ago, supercurio said:

you cannot compare with a linear scale of people being different height.

Durability may not be a linear scale, but it sure ain’t a vertical one either. At least in my language.

 

2 hours ago, supercurio said:

After reading everyone knowledgeable's posts in the related threads, you will find each describe the design as faulty.

When Tawpie answered my question about whether the mosfets see the full battery voltage, the answer was that they’d need to see the schematic in order to be sure.

 

2 hours ago, supercurio said:

A MOSFET with breakdown voltage of 100.0000V is within specification, despite it might make the V12 self-balancing algorithm fail on a bump

And if that were the case, you’d be right and the mosfet was a wrong choice for the intended use. But I’m definitely not able to assess all the relevant factors that are unavoidably at play here. To me the main questions are whether the steps Inmotion has taken so far are sufficient or not, and whether they have been truthful in their public comments. So far I don’t have a reason not to believe them.

 

2 hours ago, supercurio said:

If not, please point out which components are.

You already know my answer to that one. Besides not having anywhere near the required knowledge, I don’t plan to own a V12, so spending more time with the matter than I currently am is just not beneficial to me. I will hear how all this pans out before ordering myself a “V13” anyway.

 

2 hours ago, supercurio said:

the stress test make 25% of the MOSFETs fail

You probably mean 25% off the units? There are 12 of these driver mosfets in each V12. 25% failed wheels is much more than the last I checked, but it would still be only about 2% of the actual mosfets.

 

2 hours ago, supercurio said:

"Nominal values for components are relatively conservative"

Considering that even these Chinese PR people sometimes need a translator to understand or type in English, I do hope that the tone that irks you in that message is not fully intended.

 

2 hours ago, supercurio said:

My goal is to pressure them to provide replacement boards using components within their specification so they have a chance to operate reliably and keep our rider community safe.
And that board seems to be designed already for the V12 HT variant.

I’m glad that your intent is more structured than what the first post made me think of. And let me be clear, I’m not standing in your way. But I do have a tendency of replying to comments that I consider overshot.

[Paul A]

Cecily Inmotion

• Inmotion Representative
• • 11
• Location: China
• EUC: Inmotion

Posted 1 minute ago

[supercurio]

34 minutes ago, mrelwood said:

I’m sure it is. I do wonder though that if they can simply decide to use a wrong component for not having to wait, how has the original trust for a safety oriented brand been able to form? That they could’ve done things like that many times before, but their “luck” simply ran out this time? All I have to go for is my reasoning, and it considers the scenario more improbable than probable.

Maybe we will know later what happened and how.

There must be turmoil in the company with strong disagreements on how to handle things, and it will take weeks at the minimum to see movement.

34 minutes ago, mrelwood said:

You already know my answer to that one. Besides not having anywhere near the required knowledge, I don’t plan to own a V12, so spending more time with the matter than I currently am is just not beneficial to me. I will hear how all this pans out before ordering myself a “V13” anyway.

I understand. You see me more invested in the topic than most because I have a V12 incoming soon to replace my V10F I can't decide yet what is the best course of action.

If I bought it at current ongoing price I would have canceled a long time ago: it won't make it for the winter riding season which was its original purpose.
I bought with a pre-order discount so it's harder to cancel. But then if I do cancel, someone else less informed might get hurt. I don't want that on my conscience either hence the motivation to find a better solution.

34 minutes ago, mrelwood said:

You probably mean 25% off the units? There are 12 of these driver mosfets in each V12. 25% failed wheels is much more than the last I checked, but it would still be only about 2% of the actual mosfets.

Good catch! I mis-spoke here: 25% of wheel failure on the stress test is not 25% of MOSFET since there's 12 of them and each of them failing, multiplying the risk of wheel failure 12x.

34 minutes ago, mrelwood said:

Considering that even these Chinese PR people sometimes need a translator to understand or type in English, I do hope that the tone that irks you in that message is not fully intended.

I disagree on that one, it's far too generous to give them a pass on a clearly false statement citing potential loss in translation.
What else could they have meant with the formulation "Nominal values for components are relatively conservative" which could have been mistranslated, besides what it says.

IMO, either:

• genuine belief that the components are suitable, despite 22% real-world wheel failure rate, which indicates some amount of denial or self-delusion
• damage control PR attempt

In a way it doesn't matter since reality disprove the statement: if components has been indeed conservatively selected, they would not pop on 22% of wheel across all production batches.

34 minutes ago, mrelwood said:

I’m glad that your intent is more structured than what the first post made me think of. And let me be clear, I’m not standing in your way. But I do have a tendency of replying to comments that I consider overshot.

Thanks, it's good advice: I'll look into how to describe the intent better in posts itself instead of clarifying later.

It's great to have people willing to write replies with counter points in order to keep the discussion balanced instead of turning into an echo chamber.

[UniVehje]

Which MOSFETs have the previous 100V wheels used? Does Gotway use ones listed for higher voltage? My experience in robotics tells me that the specification  usually accounts for normal intended usage with enough tolerance. Meaning you don’t usually need to use 150V parts for 100V wheel just because voltage might sometimes go over the spec. 
 

Also:

"never attribute to malice that which is adequately explained by stupidity."

I’m not a fan of jumping into conclusions and claiming purposeful intentions in bad faith for saving some money. The cost of losing the reputation is too much. They’d be very stupid to do so. That’s why I’ll assume first an honest mistake or actual supplier issue (happens a lot in China). But let’s see how it develops. Definitely good to discuss this. 

[RagingGrandpa]

1 hour ago, UniVehje said:

Which MOSFETs have the previous 100V wheels used?

From the megathread:

On 1/6/2022 at 11:59 AM, RagingGrandpa said:

Gotway/Begode/Leaperkim is 125V

V12 100V FET is Infineon 23N10N5. About $4 each!
And the Gotway 125V FET is Hooyi 5012. $0.90 - $1.90/ Piece.

If you get lucky with component variation, it's perfectly likely that some [V12] boards will survive...
(we still don't know if the failure rate is due to variation alone; or if truly defective parts that don't meet the minimum spec made it into production)

Edited January 7, 2022 by RagingGrandpa

[supercurio]

24 minutes ago, RagingGrandpa said:

(we still don't know if the failure rate is due to variation alone; or if truly defective parts that don't meet the minimum spec made it into production)

We still don't know, but a trusted distributor told me 30% of his summer batch V10F failed also. And aren't they supposed to use the same Infineon IPP023N10N5?

It was not discussed anywhere but Inmotion has this information, although they left the distributor in the dark without answer.
This probably contributes to their conclusion that V12 failures are due to defective parts in the in the FET supply instead of a design issue.