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Downhill + 240 LBS = Torn off ligaments and three fractures


ImpulseZeo9201

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5 hours ago, Smoother said:

Wow! That's a great picture.  I'm half tempted to replace my current picture with it. brilliant.

 

Sorry, yes I know that.  What I thought I was saying was : he wasn't slowing down, and therefore not calling for an additional amp spike, other than the amps his steady constant decent was already using.  But I thought wrong.  Sometimes these reports can seem wordy, but it is necessary in order to convey exactly what one means.  In this case I failed. Mia culpa ?

 

On on a different note.  Do you think we should split this thread.  We seem to have hijacked the OP s crash and injury report, making light of his severe injuries, and accompanying pain.  No one should have to endure that.  The pain I mean, not the hijacking.

Take its yours   :thumbup:

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Very sorry to hear this.

I like hill riding especially fast hill riding but I do follow certain rules(will be described later in my upcoming post).

However, once I rode up my V3 on a very steep slope of about 27 degree, the board got fried. I'm 75kg and I successfully rode that slope on my IPS T260 and Gotway MCM2 before. I failed on my V2 MS thought because it just gave in.

After the replacement of the mainboard, I tried hard idling by hold up something in case the EUC gives in, and I almost killed it again. There was a big noise in the EUC and one of the fuse(I installed) blew. I recorded the event by my GL220 and it shows the current from the battery has reached to 115A and the voltage dropped to 30V for about 0.15 second. The actual current may be even larger because the current sensor reached to the limit. I don't know what really happened at that moment, may be the MOSFET bridge shorted, may be the armature of the motor saturated, may be there was a slippage of poles.

Several days ago, I was ridding and stopped and standing on my right foot, with my left foot on the left pedal, but the right pedal accidently touched the stone curb. The EUC struggled a little bit and suddenly died silently. I cannot turn it back on, and the MOSFETs are intact. Of course I replaced the board the second time,,,,(omitted for 100 words),,,, and the third time to V3s+,,,,,.

What I can say from these experiences(plus other similar happening I've witnessed), is that the board of V3 is fragile.

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@zlymex. Sorry to hear the trouble you've had with v3. It's good you're handy with electronics. Do you work in the electronics industry, you seem to know a lot about this stuff. 

@FLASH thanks. I accidentally tried it but it didn't look good in that tiny circle. But since I had lost my original, I found my new super hero outfit, which is more in keeping with my recent short flight followed by face plant. 

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7 minutes ago, Smoother said:

@zlymex. Sorry to hear the trouble you've had with v3. It's good you're handy with electronics. Do you work in the electronics industry, you seem to know a lot about this stuff. 

Thanks, My work is not related to electronics, it is just one of my hobbies.

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14 minutes ago, Smoother said:

@zlymex. Sorry to hear the trouble you've had with v3. It's good you're handy with electronics. Do you work in the electronics industry, you seem to know a lot about this stuff. 

@FLASH thanks. I accidentally tried it but it didn't look good in that tiny circle. But since I had lost my original, I found my new super hero outfit, which is more in keeping with my recent short flight followed by face plant. 

Looks great but dont forget your helmet  ;)

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2 hours ago, zlymex said:

Very sorry to hear this.

I like hill riding especially fast hill riding but I do follow certain rules(will be described later in my upcoming post).

However, once I rode up my V3 on a very steep slope of about 27 degree, the board got fried. I'm 75kg and I successfully rode that slope on my IPS T260 and Gotway MCM2 before. I failed on my V2 MS thought because it just gave in.

After the replacement of the mainboard, I tried hard idling by hold up something in case the EUC gives in, and I almost killed it again. There was a big noise in the EUC and one of the fuse(I installed) blew. I recorded the event by my GL220 and it shows the current from the battery has reached to 115A and the voltage dropped to 30V for about 0.15 second. The actual current may be even larger because the current sensor reached to the limit. I don't know what really happened at that moment, may be the MOSFET bridge shorted, may be the armature of the motor saturated, may be there was a slippage of poles.

Several days ago, I was ridding and stopped and standing on my right foot, with my left foot on the left pedal, but the right pedal accidently touched the stone curb. The EUC struggled a little bit and suddenly died silently. I cannot turn it back on, and the MOSFETs are intact. Of course I replaced the board the second time,,,,(omitted for 100 words),,,, and the third time to V3s+,,,,,.

What I can say from these experiences(plus other similar happening I've witnessed), is that the board of V3 is fragile.

Dammit, you're making me very nervous of my MS3 :unsure: I've tried to go up 27 degree hills, and have been lucky so far, but not nice to know I may have only just got away with it... oh well - I suppose forewarned is forearmed etc etc...

How much is a new board ? Makes me think I should get a spare so I don't have to wait 3 months without a wheel while I order a new one if it blows :)

CBR

 

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13 minutes ago, Cerbera said:

How much is a new board ? Makes me think I should get a spare so I don't have to wait 3 months without a wheel while I order a new one if it blows :)

CBR

 

I don't know the price, Gotway is kind enough to replace the bad ones and give me a spare for free.

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Just now, zlymex said:

I don't know the price, Gotway is kind enough to replace the bad ones and give me a spare for free.

Oh right - well that's pretty decent customer support isn't it... every cloud etc :)

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4 minutes ago, Cerbera said:

 

Oh right - well that's pretty decent customer support isn't it... every cloud etc :)

Sure. There are at least eight V3 in my city, I'll make the spare for all.

BTW, all the board related incidents I saw were happened at low speed, but large torque.

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16 hours ago, zlymex said:

<snip>

However, once I rode up my V3 on a very steep slope of about 27 degree, the board got fried. I'm 75kg and I successfully rode that slope on my IPS T260 and Gotway MCM2 before. I failed on my V2 MS thought because it just gave in.

<snip>

I think 26 degree slopes should be OK ;)

Do you guys go around measuring all of your hills with an inclinometer?

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14 hours ago, zlymex said:

I don't know the price, Gotway is kind enough to replace the bad ones and give me a spare for free.

Did you buy your unit from gotway? That's. I've they did that for you.  I know speedy feet U.K. Sell them I think for like $150 US which is not bad and he ships right away and has them in stock based on his website. 

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On 11/14/2016 at 8:24 PM, ImpulseZeo9201 said:

I found out that there are not only limits to how fast but also on how much breaking or voltage or whatever you can draw from those machines.

On the steepest hill in my neighborhood, my IPS wheels feel like they are maxed out for keeping my descent under control. Let me be clear, I have descended this hill countless times and never felt unsafe. However, it feels close to the limit. I have often wondered what would happen if I were heavier (I am about 66 kg).

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1 hour ago, Donafello said:

Did you buy your unit from gotway? That's. I've they did that for you.  I know speedy feet U.K. Sell them I think for like $150 US which is not bad and he ships right away and has them in stock based on his website. 

I bought my V3 from a local authorized dealer, who in turn ordered the EUC from the general agent in China.

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16 hours ago, zlymex said:

Gotway is kind enough to replace the bad ones and give me a spare for free.

I think we are seeing yet another in a long string of examples of insufficient testing before EUC release. Thorough testing should have revealed that these boards blow too easily.

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So do we have an answer yet for 'how many amps is too much for the MS3 board' ? I hit 50A a couple of times during acceleration up fairly innocuous slopes on my town run today, which is 10A more than I have ever peaked before... but it didn't blow the board, so do we know 50A, at least briefly, is OK ? Any higher offers ? :)

wheel-log-20-11-2016-C.jpg

 

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1 hour ago, Cerbera said:

So do we have an answer yet for 'how many amps is too much for the MS3 board' ? I hit 50A a couple of times during acceleration up fairly innocuous slopes on my town run today, which is 10A more than I have ever peaked before... but it didn't blow the board, so do we know 50A, at least briefly, is OK ? Any higher offers ? :)

Gotway said the limit is 120A. I believe this because I hit 110A in one of my idling tests without problem.
V3-idling.gif

In real hill climb situations of about 15% slope, I reached 60A once, at speed between 15 to 20kph
V3-Hill3.gif

Note that the green curve captured by Wheellog is the armature current, I sometimes added the battery current as above blue curve, which can be negative when downhill indicating regenerative charging.

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10 minutes ago, zlymex said:

Gotway said the limit is 120A. I believe this because I hit 110A in one of my idling tests without problem.

In real hill climb situations of about 15% slope, I reached 60A once, at speed between 15 to 20kph

Note that the green curve captured by Wheellog is the armature current, I sometimes added the battery current as above blue curve, which can be negative when downhill indicating regenerative charging.

Thank you, that is very helpful...

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To answer the question of how many hills where involved in my ride. Around 10 I would say.

Those hills were no joke. Going up and down many steep hills I felt fairly confident in the capabilities of the machine although knowing that there are limits on what electric motors can be put through, I thought I'm within them. Perhaps my subconscious affected the wheel after seeing what our mind can do to machines. Especially as I was thinking about potential magnet slippage/ overcurrent 10 seconds before the crash.

Interesting experiment

And its totally fine to take the threat and make some scientific estimates, I just want people to be aware of the possibility of limits

 

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My Previous Statement:

"Below some threshold of speed  regenerative breaking is not possible anymore (generated voltage too low to charge the battery) - since all wheels can  brake until standstill there has to be an "active power consuming" braking mode..." "

Quote

This comes up at regular intervals, but, as Scotty said:" Ye canna break the laws o' physics Captain!".

...

So, regardless of the speed the wheel is turning (and you need to remember that there are a great number of pole pairs on these motors so the RPM, or correctly the a.c. cycles, the electronics is experiencing is the wheel RPM multiplied by the number of pole pairs) power is flowing into the battery, if at any point power flows out of the battery whilst leaning back, the wheel has to be physically going backwards.

I guess it is just about possible the software might switch the MOSFET's in such a way that they short the coils once back e.m.f. has reduced below a certain level and rely on the heat being dissipated through the motor windings, but that risks overheating the motor and possibly over current the MOSFET's so I'm not at all convinced any of the controllers are that sophisticated?

...

After some rereading and new readings i think i gained some more understanding (and some new questions i am not capable to formulate by now... ;) ).

Imho my mistake was, that the generated voltage by the motor which was on some points stated as kV * rotational Speed is "just" the no-load voltage generated by the motor. So while braking with a certain torque a certain proportional current is induced in the coils which generates a voltage that is just high enough to charge the battery with exactly this current (thanks for this hint @Keith!).

By the difference of the commutation frequency and the wheel rotational speed this torque(~current) is adjusted. (e.g. by the leaning backward of the driver which causes the firmware to try to balance him by adjusting the commutation...) And so regenerative braking is possible down to (almost) standstill.

Regarding the "active power consuming" braking - here exists beside the short circuiting of the coils one braking method called plugging braking. Which as far as i understood switches the polarity of the coils to the battery. (Should be achieved by phase shifting the commutation sequence?) But by this the Voltage gets much higher (times 1.5 - 2.5 was mentioned in one TI blog) - one gets the induced voltage from the coils added to the Battery. So the Mosfets, capacitors,etc would have to withstand much higher voltages. Since these are not used in EUCs this braking technique should never happen... And as far as i have read it is more power consuming than just shorting the coils...

In some articles these two braking techniques (regenerative vs. plugging) are also imho just distinguished by sub versus super syncronous speed of the motor acting as generator == if the motor rotational speed is above or below the commutation frequency. (Could also be that i understood these wrongly - they would need some more time and thinking from my side to understand them and follow the authors...;( )

So it could be that some fried boards while braking resulted from the firmware applying the "wrong" commutation frequency to the motor, which caused the voltage to about double and current to multiply... ? Edit: Just the current needed to perform strong braking, especially with already stressed batteries (higher internal resistance so higher generated voltage necessary), should be enough to fry these boards - imho no need for new thoughts about this...?

@Smoother: So point 7 of your summary has to be reformulated!

Edit: the torque/current/viltage theory seems to be false or at leat not enough to be used for regenerative braking. In http://eacaspian.ir/wp-content/uploads/2015/06/EB1.pdf is a nice explanation how voltage boosting for regen braking works...

 

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On 19.11.2016 at 7:30 AM, Smoother said:

7. EUC's either, regenerate or draw power when descending, depending on the load on the motor, and switch in response to small changes in speed, wind, hill angle, etc).  Regeneration can only produce a finite amount braking force ( less than the power of the motor) after that active application of power is used to electrically brake the wheel.The load is comprised of total vehicle weight (rider, wheel, baggage), the grade of the hill, the speed selected, changes in speed ( either from braking or accelerating), wind direction (front or behind), road surface.  ( bumpy producing more power peaks than smooth).  

 

15 minutes ago, Smoother said:

really? Which part of 7? it was a long point, and my brain is still swimming from reading your post. Notice I said reading, not understanding.?

It should get much easier:

7. EUC's regenerate power when descending/braking.

Maybe at very slow speeds some additional braking force is introduced by shorting the motor coils - imho not? I really have absolutely no idea if regenerative braking at very low speeds is still efficient to produce enough braking torque and shorting the coils (even for short moments) introduces not way to much current....

I hope very much, that @electric_vehicle_loverand @lizardmechmake good progress with the open source firmwares and publish here their findings extensilvely! ;)

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20 hours ago, Chriull said:

Maybe at very slow speeds some additional braking force is introduced by shorting the motor coils - imho not? I really have absolutely no idea if regenerative braking at very low speeds is still efficient to produce enough braking torque and shorting the coils (even for short moments) introduces not way to much current....

I hope very much, that @electric_vehicle_loverand @lizardmechmake good progress with the open source firmwares and publish here their findings extensilvely! ;)

Yes, I also think that at very low speeds the BEMF generated voltage (power) is very low to impose a current flow to the battery and so that motor brakes. On that situation the brake can be done by shorting the motor coils -- anyone can test this, by shorting by hand a EUC motor phases and try to rotating it, it is very easy to feel the force needed to make the motor rotating when the phases are shorted or not shorted.

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I have had my wheel continue after I jumped off and keep riding for 30 - 50 feet more. I too could see a runaway wheel either damaging something or hurting someone. Questions that I've mulled over are:

  1. Do I need to find some type of insurance to cover myself/property in the event of an accident?
  2. What about Personal Injury or Liability in case my wheel is involved in the accident while I'm no longer on it?  (A runaway wheel could damage a car or causee serious injury to an insuspecting pedestrian.)

My shorter term solution has been a leash I attach to my X8 when I plan on riding hills or around more people. It is basically a surf board leash that velcros around my ankle and is attached to one of the pedals. (The first version I had was a clip that looks like a tape measure similar to those you see on janitors holding their key chain. My intention is not to stop the wheel, but just to throw it off balance so it falls over in the event we get separated.

(Again, I totally expect/plan my leash to break or loosen if needed so as not to cause more injury to myself when the rope secured to the 25lb one-wheeled weight becomes taunt. I merely want to destabilize the balancing mechanism of the EUC so it hits the ground and stops) 

 

 

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On 17/11/2016 at 8:56 AM, Hunka Hunka Burning Love said:

Eh, people tend to ignore my questions as my smilies tend to dazzle them too much. :w00t2:  I wonder though whether there is a possibility that the fall in the OP's case could have been due to rider error and maybe not a fault of the wheel?  For a new rider who has his first wheel for 1.5 wheels to tackle the steep hills of San Fran that's pretty ballsy.  Add in some subconscious questions and borderline weight limits, could that possibly be a factor in the accident?  Could the tire have lost traction on a slippery spot maybe?

If anyone's interested we did talk briefly about failures going downhill a while back when I posed the question to the forum. There's some interesting replies in this thread if anyone's curious.  I was trying to find that one video of that professional reviewer with the Madmax mask on who lost control of his EUC, and it hurtled down a long hill...  I think Toby Stevens also had a video showing his wheel bouncing down a hill out of control...  That's when I ran across this thread...

 

Tobe's debacle with the hill was down to operator error. He was riding two wheels (one under each foot) along a bumpy track at the top of a pretty steep slope. Upon "dismounting" his wheel (not mine luckily) began to head down the hill and then started to tumble and get faster and faster. When it got to the bottom of the hill, luckily it missed the river and bounced across a stone bridge and came to a halt the other side on a rocky path. Tobe eventually reached it, turned it off, flicked it back on and rode it back up the path. It was his original Airwheel X3 and astonishingly it survived with a few scratches. He did eventually kill that X3 by drowning it!
It's at 2m19s of the linked movie.

 

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