V8F cutout with no warning??

[NZDoug]

A strange thing. Ive had the v8F since December, and loving it.... until yesterday. 80% charge, 15 min in, traveling slow, maybe 10k. I went off a curb, and it suddenly cut out,  (pitching me onto the gravel) Now its completely dead.... so im thinking its a fuse or PCB is totally burnt out. If its fuse, fine, but could it happen again, maybe doing 30k??

What could it be and why? Could it be related to the fact that the previous day i ran it out of power after 55 k, and had to walk home? would that have damaged the board?

Im planning to open it up and see, but what should i look for and how confident should i be in the future with it??    Doug 

[Chriull]

15 minutes ago, NZDoug said:

Now its completely dead.... so im thinking its a fuse

Does it turn without resistance?

15 minutes ago, NZDoug said:

or PCB is totally burnt out.

This would normally be a fried mosfet shorting the motor causing resistance.

15 minutes ago, NZDoug said:

If its fuse, fine, but could it happen again, maybe doing 30k??

At 30k this normally does not happen. Currents are lower! But at higher speeds one has with too strong accelerations one can easily overlean - feels about the same but mitherboard and fuse is not burdened...

[Paradox]

I hope you were geared up and suffered no injuries. 

[NZDoug]

2 hours ago, Chriull said:

Does it turn without resistance?

This would normally be a fried mosfet shorting the motor causing resistance.

At 30k this normally does not happen. Currents are lower! But at higher speeds one has with too strong accelerations one can easily overlean - feels about the same but mitherboard and fuse is not burdened...

Actually you are right, i had not noticed, yes definitely some resistance. What is a mosfet? is it on the board? 

[NZDoug]

2 hours ago, Paradox said:

I hope you were geared up and suffered no injuries. 

thanks yes, i had the gear on, and it was low speed.....im in one piece, but severely bruised quads so ill limp for a while...

[mrelwood]

5 hours ago, NZDoug said:

What could it be and why?

If the motor feels stiff when turning the wheel by hand, it’s almost certainly a blown Mosfet on the main board. Mosfets are the components on the board that do the heavy lifting.

 Not much point in opening it up yet. You’ll need a new main board, and the skills/patience or a friend to swap the board.

[Ek.]

@NZDoug Welcome to the forum. I see you're a kiwi - where did you get your wheel? If you bought it from Roll.nz they might be able to give you some advice about it. If you live in Welly or Auckland you can probably find someone to help you fix it. Definitely if you're in Wellington (Roll.nz is there).

[Unventor]

Going up or down curbs at slow speeds is probably the most "dangerous" thing to do because of 2 contradicting situations. 

As a rider slowing down is intuitive instinct as you risk less at lower speeds. It is easier to bail and walk off if you loose balance. 

But to the wheel it has no help from moment of movement and at lower speeds it has to pull more current to handle the spikes to keep balance.

With "smaller" wheels the spikes you make by this is bigger pr cell too and with smaller rim diameter the more force it takes to pull up a curb too. 

Now I think this is part what Inmotion realised now and why the V11 and V12 is much more powerful in so many regards. Also suspension will help to avoid some of the big spikes. But there will still be spikes going up or down curbs or over bumps or holes.

But as soon you use your wheel for more "practical" riding and not just a flat lean surface, there is a risk of what @NZDoug posted here. And to me that is why the market in general is moving away from last mile communiting devices, because EUCs can do so much more, if the size is bigger.

[NZDoug]

16 hours ago, mrelwood said:

If the motor feels stiff when turning the wheel by hand, it’s almost certainly a blown Mosfet on the main board. Mosfets are the components on the board that do the heavy lifting.

 Not much point in opening it up yet. You’ll need a new main board, and the skills/patience or a friend to swap the board.

ouch, OK, thanks very much for your help, much appreciated!

 

[Nostris]

Hi NZ Doug... Glad you survived.  Can you post up what the problem was when you’ve had the post mortem done on the wheel, as another V8f rider, I’d be interested. 👍

[Steve50]

On 4/23/2021 at 9:50 AM, Unventor said:

Going up or down curbs at slow speeds is probably the most "dangerous" thing to do because of 2 contradicting situations. 

As a rider slowing down is intuitive instinct as you risk less at lower speeds. It is easier to bail and walk off if you loose balance. 

But to the wheel it has no help from moment of movement and at lower speeds it has to pull more current to handle the spikes to keep balance.

With "smaller" wheels the spikes you make by this is bigger pr cell too and with smaller rim diameter the more force it takes to pull up a curb too. 

Now I think this is part what Inmotion realised now and why the V11 and V12 is much more powerful in so many regards. Also suspension will help to avoid some of the big spikes. But there will still be spikes going up or down curbs or over bumps or holes.

But as soon you use your wheel for more "practical" riding and not just a flat lean surface, there is a risk of what @NZDoug posted here. And to me that is why the market in general is moving away from last mile communiting devices, because EUCs can do so much more, if the size is bigger.

Ive seen other v8f owners doing that and they have had no problems with it so it must be just the rare unlucky ones that has the bad one.

[Unventor]

On 10/19/2021 at 3:19 AM, Steve50 said:

Ive seen other v8f owners doing that and they have had no problems with it so it must be just the rare unlucky ones that has the bad one.

I am maybe not the best to explain this. But what you see others do is not the same it doesn't pose a risk.

First of there is no such thing as rare unlucky ones when it comes to EUCs behavior. That is why we need to learn from when things did't go as we expected.

The biggest demand you can put on a wheel is at low to stand still speed try to climb over obstacles. It has to do with the power needed since you don't have any momentum to help you. And that the force you need is from  power (watts) you need over the time you need it. And how this works out in a wheel.

The formulas I talk about I got from this site to explain this in english: https://www.thesciencehive.co.uk/electricity-gcse

andthis leads to 

So you power need is high over a short time to maintain balance, and at low speed the motor draw low voltage (this is how it was explained to me) so to get high amount of power it has to draw very high current. This put a lot of strain on a battery pack, expectantly if it have few cells. 

So the trick is to have a little speed but not too much either, and you help the wheel over the curb, This can be done in 2 ways, one either try to squeeze the tire to make it bounce (which take a lot of practice as you don't want to over power the wheel doing this) or you jump up taking the weight off that the wheel needs to lift. This means you are not as locked into the pedals so you have a risk of loosing friction with the pedals. So timing and practice is everything. done right it looks easy. any curb over 1-1.5" I prefer to step down on a non-suspension wheel. But it depends on the curb and how I can approach it.Most will need to have some lower side pads to be able to control this, especially on heavier wheels. The V8f however is a relative light wheel so some "baby euc" foam padding might be enough.  

• NOTE: There are always those that knows better or don't this physic apply to them. But to understand this take a bike and test out stand still vs coming at low speed vs coming at low speed and pull handlebar to lift up the front wheel while not sitting on the saddle.
• Also important to have enough tire pressure to handle the impact, bicycle or EUC regardless. 

This is one of the best videos showing what to do I ever seen. 

 

Edited October 20, 2021 by Unventor

[Heymelon]

On 10/20/2021 at 11:43 AM, Unventor said:

 

Frst of there is no such thing as rare unlucky ones when it comes to EUCs behavior.

Really? Seems the bricked or dead on arrival units or bad parts, battery fires, software glitches and other such cutouts indicate you can get unlucky with your EUC. And it is not all up to user behavior. But of course we can increase or knowledge and minimize the risk or strain in most areas! So the momentum point you make is very interesting indeed. I think op got off a curb though, and I'm pretty sure we should be able to do that with or without momentum without triggering such a high power spike that a board or fuse fries? I certainty haven't gotten any crazy high current readings from going on or off curbs yet. Though I did blow a fuse off road hill climbing and hitting some mud while the wheel was already very taxed lol.