'Face-plant'

[AlanR]

I experienced my first 'face-plant' yesterday; or was it my ineptitude!

Turning a corner fairly sedately when the EUC just went backwards with me falling flat on my face. Thought I had broken my wrist - luckily no.

Now what caused it? The EUC just seemed to fly backwards without any resistance so I could bring a foot up under me!

Anyone experience this type of thing?

Also, I now have wrist, knee and elbow guards!   Should I wear a helmet?

 

[zentype]

I'm glad you didn't break your wrist! From your last sentence I'm guessing you didn't have wrist protection when you fell?

I'm not sure what may have caused it, being still fairly new at this. What brand wheel were you on when it happened? I'd hate to think that this happened to one of the big name wheels... 

If it really happened on its own, then it could be a mainboard or sensor malfunction...  Or did it perhaps stop suddenly and you kept moving forward so it felt like it went backwards?

If it did what you said and the EUC is in question then the additional protection is definitely something you should wear.. And if you travel at speed, then yes a helmet as well. Better safe than sorry until you figure out the cause and fix it.

 

[Gaston]

Did you take the corner hard? Did you scratched the ground with the pedals heavy? So did you come close to the 45 degree side switch off?

[Cloud]

These stories really scare me. If the wheel gives out under me one day, this is not going to end well, considering the speeds i am going at and all the obstructions , traffic and people i go arpund. hope this was not the wheel randomly stopping, but something that was done wrong , we can all learn from it and and avoid this happening again.

which wheel was it?

[AlanR]

The EUC is a typical generic @asaj informs me -' Dragonmen Hotwheel' quite cheap $A350 [haggled down from $A600!] 14 inch wheel, 350 kW motor, 132 Wh Samsung battery.

After about 5 mins got back on and it behaved fine until I got home ~ 10 mins!         Riding very conservatively - my wrist was very sore still!!!

No, I don't think I was anywhere near 45' angle - but can't be 100%.     Well below 14 kph.

Pretty sure I had little forward momentum; definitely felt like the wheel just went backwards!

 

[Jag_Rip]

On my ninebot the pedals hit the ground before the 45° sideangle shutdown, dont know about the other brands, but I'd say if your pedals didnt scrap the ground it shouldnt be that kind of shut off.

Did you hit a bump during that turn maybe?

[AlanR]

I'm surprised, my EUC pedals hit the ground at about 30' !!!         I can't say for sure whether the pedals hit the ground and spun me around!

Yes, a small bump from road to sidewalk curb - a rounded 1/2 inch tall edge!

Does shutdown allow the wheel to 'freewheel' or lock it up?  It felt to me like it freewheeled because pushing down on it gave no resistance - hence straight down for me!

[Tom]

 

Does shutdown allow the wheel to 'freewheel' or lock it up?  It felt to me like it freewheeled because pushing down on it gave no resistance - hence straight down for me!

If the wheel totally cuts out it will freewheel and either shoot forwards or backwards depending on how your weight was balanced at that split second and how fast you are going.

[dmethvin]

@AlanReith Your wheel sounds a lot like my generic wheel. I don't ride it much now, but when I did I had a couple of of bailouts when it just seemed to slow down for no reason. In both cases I got back on and could ride normally. I am guessing a 132Wh battery just can't handle the current draw that the EUC needs at times. Both of mine happened when the battery was less than half full. Strangely, though, I had ridden it at other times all the way down to the battery tilt-back (8km) without any problems.

[MrBump]

When I'm down to 2 lights on my generic I'm always poised for an assassination attempt.

[Daan]

An eWheel should just never cut-off unexpectedly ever! It is not acceptable and should not happen. I guess because it is a generic it just doesn't have the right safety mechanisms and you triggered the BMS (battery management system). Please shunt it for your safety.

Of course, if you enjoy the eWheel -- start saving and buy a safer wheel from a bigger brand; (the following latest models all seem quite safe: Gotway MCM4, IPS Zero / Xima Lhotz, all the newer Kingsong's, all Solowheel's, Ninebot E+/P, etc) 

[MrBump]

I have no idea how to shunt it, and given the low power I'm not too sure how much safety it would add.  I agree it's not an acceptable state of affairs - still at the beginning of the warranty but yeah, guess I should think about working out how to shunt it...

Very tempted by the Xima Lhotz, but still just learning the basics.

[PedalFaster]

An eWheel should just never cut-off unexpectedly ever! It is not acceptable and should not happen.

That is wishful thinking uninformed by physical reality

Any wheel you can construct to ride will reach a point where it can no longer do its job of maintaining balance, and if ridden aggressively enough can reach that regime without having the reserve of acceleration needed to create a tilt-back warning.

Some designs may shut down earlier than some believe they need to, but all can be ridden to a point of failure.  

- It is not necessarily clear that continuing to turn the motor while failing to accelerate sufficiently to maintain balance is preferable to a complete shutdown; for one thing it potentially leaves the wheel chasing the falling rider

- It is pretty clear that a proactive shutdown in the case of electrical fault is preferable to a battery fire

 

[Jason McNeil]

That is wishful thinking uninformed by physical reality

Any wheel you can construct to ride will reach a point where it can no longer do its job of maintaining balance, and if ridden aggressively enough can reach that regime without having the reserve of acceleration needed to create a tilt-back warning.

I've tried every mainstream eWheel (apart the new MCM4) & own more than I care to confess. With the exception Solowheels (which are pretty slow & uninspiring with the factory firmware) & the new KS 800w motors, what you say is true. But Daan is right, maybe better clarified, that under normal & even aggressive riding styles, a Wheel should really never cut out—of course there can still be conditions where even these powerhouses can be made to fail, like trying to accelerate up 100m vertical at 30°. It's all to do with margin of power & capability of hardware. Solowheel's design philosophy has also been to provide a Wheel that has 3-4x more potential power than is employed by your typical rider: from an engineering perspective, it's profligate waste of resources, but there's a good arguments to be made on safety grounds that the losses of capacity (of the battery cells) are worth sacrificing for a Wheel that never cuts-out.

[MrBump]

I looked on the other thread and there was a lot of argument - is it definitely generally accepted now that shunting is better than not shunting? 

[Jason McNeil]

Shunting is not without it's share of risks/downsides: 1) invalidates any chance at redeeming the warranty, 2) batteries may still not be able to sustain the power reqs, 3) with some brands, like IPS, you can't shunt as the BMS, as is part of the control-board, 4) there may be associate problems like over-depletion, 5) shorten cell life. At the end of the day, you can buy a Wheel that has some thought about your safety or you can buy a cheap Wheel which will likely injury you. 

[MetricUSA]

Well had my second fp, last Friday, down to one led, full speed, and feeling good and fucking around, doing side to side and back and forth movements... Last time I think I leaned too forward as the eu raced on afterward, be this time it definitely stop going and piviot me downdown. If I had just rode straight it would not have happened and made it home....nay... Bad wrist sprain, lucked out...

[MrBump]

At the end of the day, you can buy a Wheel that has some thought about your safety or you can buy a cheap Wheel which injury you. 

There are plenty of expensive wheels with shutdown issues.

[cg]

I have no idea how to shunt it, and given the low power I'm not too sure how much safety it would add.  I agree it's not an acceptable state of affairs - still at the beginning of the warranty but yeah, guess I should think about working out how to shunt it...

I shunted my generic crap wheel, and makes a huge difference.

Now I can feel the wheel suffocating under me when there is low battery  but better it than me.

[MrBump]

I shunted my generic crap wheel, and makes a huge difference.

Now I can feel the wheel suffocating under me when there is low battery  but better it than me.

At the moment I'm just not riding under low battery conditions, but I'll probably shunt it once the warranty runs out.

And once I figure out how to do it...

[Jag_Rip]

Yes, a small bump from road to sidewalk curb - a rounded 1/2 inch tall edge!

That sounds awfully like a power surge or spike that triggered the BMS to shut down, hence it freewheeled and sent you flying. But hey, that way the battery was safed! Your potential injuries will heal y'know

As far as I understood these Shutdowns on generic wheels come from their generic BMS that were originally developed for e-Bikes where it does not matter in what situation the engine switches to free-wheel since you only loose some power-support. But on a one-wheel thats just total BS to do, especially if its a single quick spike like a bump you roll over produces.

The risk of shunting is by making it physically impossible for the BMS to shut down, hence you could overcharge or undervolt your battery and that could damage it or in rare extreme cases light it on fire. The rare extreme case would be the rider ignoring ALL warning signs and keep pushing the wheel hard and over longer durations.

Now choose what option presents the bigger risk to you and your style of riding.
 

[Tom]

That sounds awfully like a power surge or spike that triggered the BMS to shut down, hence it freewheeled and sent you flying. But hey, that way the battery was safed! Your potential injuries will heal y'know

As far as I understood these Shutdowns on generic wheels come from their generic BMS that were originally developed for e-Bikes where it does not matter in what situation the engine switches to free-wheel since you only loose some power-support. But on a one-wheel thats just total BS to do, especially if its a single quick spike like a bump you roll over produces.

The risk of shunting is by making it physically impossible for the BMS to shut down, hence you could overcharge or undervolt your battery and that could damage it or in rare extreme cases light it on fire. The rare extreme case would be the rider ignoring ALL warning signs and keep pushing the wheel hard and over longer durations.

Now choose what option presents the bigger risk to you and your style of riding.
 

What is the potential worst case scenario with a shunted battery whilst riding? I'm thinking about shunting my 88Wh generic, and plan on only charging it whilst I'm in the room (only takes ~40 mins to charge anyway) then unplugging it so theres no risk of fire whilst it's unplugged (I hope?) but how about riding? If I keep pushing the motor on low battery will the battery just break or explode? In that case isn't the end result compared to the BMS shutdown still the same?

[Jag_Rip]

Really the worst is if the battery catches fire. Still annoying but less dangerous if the battery gets damaged and wont charge anymore or you end up with less capacity.

This link explains potential problems with li-ion batteries pretty good:
http://batteryuniversity.com/learn/article/safety_concerns_with_li_ion

A idling shunted battery is as safe as every other, so no concerns there. Charging, depends I guess on the method, if the charger controls when the battery is full and stops charging, all is OK, but if they rely on electronics inside the wheel to tell the charger to stop, you better use a failsafe while charging (a timer, human supervision or similar)

Disclaimer: I am NOT a specialist (actually I am pretty dumb when it comes to voltages amps and electricity in general), I am just that parrot Molly that repeats what was discussed in this forum in various posts. Qwook! Molly now wants cracker!

[PedalFaster]

Charging, depends I guess on the method, if the charger controls when the battery is full and stops charging, all is OK, but if they rely on electronics inside the wheel to tell the charger to stop, you better use a failsafe while charging (a timer, human supervision or similar)

One cannot safely charge a high-cell count lithium pack using an external charger which monitors only the overall pack voltage.

Instead, it is necessary to monitor the individual voltage of each cell, to insure that no individual cell reaches a dangerous voltage which might be concealed in the total by the lower voltage of a different cell.

And no, paying attention to it manually is nowhere near a sufficient substitute, most obviously because you have no way of monitoring the critical per-cell voltage either.  Nor can one assume that a lithium cell which has been stressed will fail immediately - there are many reports of failures manifesting sometime after the causing incident, while the cell was seemingly "just sitting there" neither powering anything nor being charged.

[esaj]

NEVER shunt the overcharge-protection mosfet(s), you should not shunt all the mosfets, but identify only the overDIScharge-side mosfets and shunt those!

If you are unsure and cannot identify the correct mosfets, and cannot do the bypass via a thick wire, do not shunt it.