V12 Cutout tracking

[Tawpie]

13 minutes ago, nosamplesplease said:

Was the initial firmware intended to limit this failure condition?

Quite possible. There are a whole host of factors involved including firmware... the 'way' a MOSFET is switched does have a material impact on its performance/operation and firmware+other parts play their role. And this is why you try to preserve your margin budget. It's very difficult to anticipate all of the inputs to the equation so you have to make some assumptions. When one assumption changes (better braking, split mode, etc.), the result can take you over the line of "enough margin" to "insufficient margin" so you want to start the game with as much budget as you can get approval for. Design margin costs money... the PCV valve in my car could/should cost $12 but because it's probably way over designed, it costs $450... and it still breaks, and I remain quite bitter about it.

Edited January 6, 2022 by Tawpie

[rolis]

26 minutes ago, Chriull said:

That's the bldc driver (inverter) with 3 H Bridges - 6 "switches". Each switch is made of 2 paralleled mosfets.

Imho paralleling is "easier" to bear more current as putting in series to bear more voltage. Especially as higher voltage models are easily available...

 

Thanks for the info. Looked up how H-Bridges are used in 3-Phase motors.

So it comes all down to the Mosfets being rated for 100V and Inmotion hoping they would handle their max rating for a long time? 

 

[Paul A]

Seems wise not to be buying the new model, first batch, new improved wheel.....and paying for the privilege of being the guinea pig.

Wait to see what happens in a few months, until all the problems get discovered and fixed.

[nosamplesplease]

There is ALOT of speculation in this thread. None of our theories have been proven, EXACTLY like Inmotion's statements. IMO neither is "correct" without hard engineering and testing numbers. Which as far as I know has not been done by anyone, there just hasn't been enough time.

 

I have express doubt in this thread and many others but I'm voicing my opinions which I assume everyone else is doing. Opinions are like... well you know.

 

None of these opinions should be trusted completely until investigation and testing has been performed. Testing like riding a questionable wheel hundreds(thousands?) of miles, or bench testing. 

 

Please don't take anyone's opinions as gospel truth, your quality of life is on the line. Make your own trust decisions. 

 

[Paul A]

Speculation of possible causes.

The numerous reports from owners are real, cutouts are real, injuries are real, not speculation.

[mrelwood]

 

21 hours ago, Mrd777 said:

Why is Inmotion not just doing a total recall on all of our control boards?

If roughly 10% of the units are affected, a recall would cost ten times more (+shipping) than to fix only the affected units. It would also take your wheel off of your possession for months, 9 out of 10 for replacing a working board with a new, possibly faulty board. If the proposed test is sufficient in revealing the affected units, a full recall would make extremely little sense. The trust in the wheel wouldn’t go up with most  people either.

12 hours ago, Paul A said:

Could Inmotion use V11 control board(s) to replace the V12 control boards?

Different operating voltage, different connections, different features, different physical shape and size… No, they couldn’t.

5 hours ago, nosamplesplease said:

Initial testing, almost everyone said the braking was NOT strong enough and a new firmware "fixed this".

There’s one fundamental issue with your thought. The V12 braking was never weak, as in not giving enough power to the motor to brake. If it would, the pedals would not stay horizontal. The V12 braking was “slow”, because it was too instant in it’s behavior, which makes the wheel cancel your braking lean before you even get to a proper braking position. So it was using too much power, not too little.

 Pedal sensitivity settings offer an easy way to confirm this. Set your wheel into a soft or medium mode, and do some medium strength acceleration and brakings. Then set the wheel to the hardest mode available, and try to mimic the amount of lean you just did with the softer mode. Result will be that the wheel accelerates and brakes slower with the hard mode.

 If you do it the other way around, be careful, because the softer mode allows you to get into a steeper lean with less effort.

 

The question I’d love to hear the answer to the most atm, is that if the mosfets are connected in parallel and in series, do any of the mosfets at any given time even see the full 100.8V voltage?

[Paul g]

5 minutes ago, mrelwood said:

 

If roughly 10% of the units are affected, a recall would cost ten times more (+shipping) than to fix only the affected units. 

I don’t think that a recall would be the good answer to the issue. Instead they should send each  V12 costumer a replacement board with proper mosfets, remaining for us to do the switch.

[Waulnut]

1 hour ago, Paul g said:

Instead they should send each  V12 costumer a replacement board with proper mosfets, remaining for us to do the switch.

This is ideal and would ease consumer worries, at least for me. Inmotion will take a loss, but gain in confidence from consumers, which will pay forward to getting more sales. 

Edited January 7, 2022 by Waulnut

[Tawpie]

54 minutes ago, mrelwood said:

do any of the mosfets at any given time even see the full 100.8V voltage?

To provide a proper answer one needs the actual schematic, but in a typical H-bridge motor driver at low speed, yes—one of the switches (MOSFETs) will see the full applied voltage, particularly when the motor isn't turning (a stalled DC motor is a DC short circuit). The diagram at the top of this article illustrates this. https://components101.com/articles/what-is-motor-driver-h-bridge-topology-and-direction-control Regen conditions mean the motor is generating power based on its rotational velocity and if the current can't flow out fast enough the voltage must rise. When you consider the pulsed nature of BLDC motor drives, inductive flyback becomes a thing and if not properly managed (really fast catch diodes, switches with fast reverse recovery times) you can see Vds spikes that are quite high.

If the battery voltage is stepped down prior to being applied to the motor, obviously the switch won't see 100.8 but when you do that, you reduce the maximum speed the motor can turn, decrease overall efficiency due to the voltage conversion and increase the IR heat losses. So I'd be surprised if there was a step down converter between the battery and the motor... might be one, but without a schematic I just don't know. Stepping down the supply voltage doesn't help mitigate the regen issues... it would just keep you from starting out in an out-of-spec operating condition.

Annnddddd. At the power levels we're talking about, I would be worried about ground bounce... where "naught volt ref" isn't at 0V because of poor grounding.

But this is all my speculation, I didn't design this circuit!

Edited January 7, 2022 by Tawpie

[onizukagto]

5 hours ago, Waulnut said:

This is ideal and would ease consumer worries, at least for me. Inmotion will take a loss, but gain in confidence from consumers, which will pay forward to getting more sales. 

But... Isn't that what inmotion is doing? 

They are giving free repair/replacement?

You just have to contact your local V12 dealer or inmotion if you bought directly. 

[Waulnut]

3 minutes ago, onizukagto said:

But... Isn't that what inmotion is doing? 

They are giving free repair/replacement?

Only if your board dies and the fix, at the moment, is replacing with the same board with 100V MOSFETs. With the limited resources, it's also possible the fix could be replacement of the damaged MOSFET, no new board.

I was referring to @Paul g's part of providing boards that have proper MOSFETs with higher rating than 100V. My v12 might not blow, but I would still like to have it replaced with a beefier MOSFETs. Inmotion should provide the v12 high torque version board as replacement for everyone when available. It would be costly but that's what will bring confidence back imo. 

[rolis]

Small update: Inmotion asked me to put their Q&A on the Page, hopefully we can gather something useful from there.

https://spurious-tea-df7.notion.site/Inmotion-V12-MOSFET-Test-statistic-7786b4fdde50416eb7dc1a4674121ec7

Edited January 7, 2022 by rolis

[supercurio]

3 hours ago, rolis said:

Small update: Inmotion asked me to put their Q&A on the Page, hopefully we can gather something useful from there.
https://spurious-tea-df7.notion.site/Inmotion-V12-MOSFET-Test-statistic-7786b4fdde50416eb7dc1a4674121ec7

It's great to have Inmotion making an effort with communicating how to run the test best, and hopefully avoid immediate danger for some.
After answering comments on their YouTube video, it's clear that many struggle reproducing the test.

There is a problem with one of their statement however, and I quote:

Quote

Q:
could the issue happen only with full battery? could mosfets be damaged by over-voltage, since voltage can go higher than nominal when breaking with full battery?

A:
No, this issue will not happen only with full battery.  And nominal values for components are relatively conservative

This is simply not true.

IPP023N10N5 MOSFET datasheet: Drain-source breakdown voltage
Minimum 100V
Typical -
Max: -

The fact is that the design violates the nominal value of the main component, with Typical source breakdown voltage being unspecified instead of "relatively conservative"

Inmotion sneaks in damage control in this Q&A, by attempting to establish a reality distortion field contradicting easy to look up facts in Infineon specifications.
At the same time, they throw Infineon under the bus by pretending that the issue was caused by bad parts.

In my opinion, they must be called out for that.

[Steve Evans]

i am 64 years old, and trying to do that stress test on my wheel really did a number on my back. 

still not sure i did the test correctly. i think i'll wait a few weeks to let my back recover then try again.

that wheel is freakin heavy.

steve

 

[Paul A]

Maybe try placing the bottom of the pedals onto some support base, (perhaps some bricks), to support the weight and lift the wheel off the ground.

Then only need to tilt the wheel back and forwards as needed.

[rolis]

48 minutes ago, evans036 said:

i am 64 years old, and trying to do that stress test on my wheel really did a number on my back. 

still not sure i did the test correctly. i think i'll wait a few weeks to let my back recover then try again.

that wheel is freakin heavy.

steve

 

This is what I am worried about. Not everybody is able to do this test properly mostly because it is a "heavy ass thing" to lift and try to cut-off mid air. Get well soon @evans036 and let somebody else try it for you.

 

These at-home self-tests shouldn´t be even a thing... I would maybe trust dealers with doing this to be really sure. 

Lets say you do the test and the wheel does not cut out. Then you go out on the road confidently thinking nothing can happen to you. Suddenly you have to break sharply and the wheel fails. I can tell you that if Inmotion would be an American comapny, you would be rich rich.

[skautas2003]

2 hours ago, supercurio said:

It's great to have Inmotion making an effort with communicating how to run the test best, and hopefully avoid immediate danger for some.
After answering comments on their YouTube video, it's clear that many struggle reproducing the test.

There is a problem with one of their statement however, and I quote:

This is simply not true.

IPP023N10N5 MOSFET datasheet: Drain-source breakdown voltage
Minimum 100V
Typical -
Max: -

The fact is that the design violates the nominal value of the main component, with Typical source breakdown voltage being unspecified instead of "relatively conservative"

Inmotion sneaks in damage control in this Q&A, by attempting to establish a reality distortion field contradicting easy to look up facts in Infineon specifications.
At the same time, they throw Infineon under the bus by pretending that the issue was caused by bad parts.

In my opinion, they must be called out for that.

There is a lot of discussion (guestimate in my opinion) about MOS not compatible with 100.8 V batteries pack systems. Does any one know max voltage that MOS in reality gets?If yes please provide data to check not opinions. Does anyone apart inmotion checked/know max working(not teoretical) MOS voltage? If no you can not tell that it is not safe to use 100 V MOS in this systems. My friend  EE told that Inmotion v12 has best architecture if you compare to gotways and KS and it has max usage not more 70% off MOS safe working range.    

[rolis]

I did not want to reply at first, but I have to.

Saying that this all is just a speculation and then solidifying your argument with:

1 hour ago, skautas2003 said:

My friend  EE told

is just ridiculous.

But I would love to hear his explanation on how and why the MOSFETs on the board see no more than 70 Volts.

1 hour ago, skautas2003 said:

it has max usage not more 70% off MOS safe working range.    

 

[wheel-life]

3 hours ago, evans036 said:

i am 64 years old, and trying to do that stress test on my wheel really did a number on my back. 

still not sure i did the test correctly. i think i'll wait a few weeks to let my back recover then try again.

that wheel is freakin heavy.

steve

 

i feel for you on that. i've got neck problems from a torn muscle awhile back, could definitely see this test exacerbating that. i'll probably try to build up a stack of 2x4's and something slightly curved on top to put the pedals on to more easily tilt it at speed...or maybe hold it like a kettlebell between the legs like the alienrides guy did in his video: https://s3.us-west-2.amazonaws.com/secure.notion-static.com/49fbebb1-dc52-4501-b8ab-9cb7ce433d03/alienrides_2.mp4

Edited January 7, 2022 by wheel-life

[Paul A]

Cecily Inmotion

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

Posted 1 minute ago

[supercurio]

3 hours ago, skautas2003 said:

There is a lot of discussion (guestimate in my opinion) about MOS not compatible with 100.8 V batteries pack systems. Does any one know max voltage that MOS in reality gets?If yes please provide data to check not opinions. Does anyone apart inmotion checked/know max working(not teoretical) MOS voltage? If no you can not tell that it is not safe to use 100 V MOS in this systems. My friend  EE told that Inmotion v12 has best architecture if you compare to gotways and KS and it has max usage not more 70% off MOS safe working range.    

It would be awesome to have someone hookup an oscilloscope and high precision current meter to the V12 phase wires when completing the stress test.

That way, one could identify not only how much peak voltage the MOS has to handle but also which amount of "avalanche energy, single pulse" it represents.
V12 MOSFET specs are:

• 100V (Min) Drain-source breakdown voltage (Typical & Max unspecified)
• 120A Max continuous drain current
• 480A Max Pulsed drain current
• 1166 mJ Max Avalanche energy, single pulse

Could your EE friend help with running the measurements you describe?

For now we don't have the data, and our only proxy is based on the observed failure rate.
In case of failure, we can conclude with good confidence that one or several of these metrics were exceeded, leading to component failure.

I'm afraid that like @rolis mentioned, the calculations of your EE friends are off however regarding the V12 safe working range.
As confirmed by glancing at the MOSFET specifications and real world failure rate.

Edited January 7, 2022 by supercurio

[WillCO]

Ran the test on my 0-mile V12, survived 10 cycles (damn this thing's heavy!)  Might go ride it tomorrow, then test again.  May don my track leathers first tho.....  

[Cress]

For-what-it's-worth - - - The above post by SuperCurio is correct.  V12 controller failures happen because Inmotion installed an inadequate power switch in an otherwise good circuit. Early failures happen in slightly out-of-spec MOSFETs, future failures happen as  the MOSFETs age (all power switches are problematic for failure with aging).  I'll use my V12 gently, test regularly knowing I don't have the V12 I paid for until I replace the Controller.  The EUC community is improving progress by continuing to track issues and inform manufacturers we know where the problems are coming from.  What's the difference between the 'Automobile' community and the 'EUC' community?  Automobile is bigger than EUC. 

[MegaObi]

On 1/8/2022 at 3:53 PM, WillCO said:

Ran the test on my 0-mile V12, survived 10 cycles (damn this thing's heavy!)  Might go ride it tomorrow, then test again.  May don my track leathers first tho.....  

nice dude!

i mean 2 or 3 times is enough to determine if your wheel got the issue (if you done it properly) and 10 is probably conservative. There is already few videos - let it spin up a little and crank it back hard. IF the mosfet is bad it will shit itself instantly due to the high power demand. the dealers themselves should do the tests before sending out the wheels, everyone else will get replacement board and problem solved. pretty shit that this was not picked up in pre-production/testing but its one of those things. no one wants to drop a few k$ on a new wheel and end up with a lemon but its pretty good the way inmotion handling it - just sucks if you need to wait till march and you dont have another wheel. i know i couldnt wait.

If anyone is in trouble and need a mosfet swapped and in Australia - drop me a PM

[rcgldr]

When doing the MOSFET free spin test, I would recommend using an old towel on the carpet | floor in case the wheel is still spinning a bit when the V12 is set back down, so it won't leave a tire mark on the carpet | floor.