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Planemo

Z10 overlean speed - too conservative?

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Having only recently felt like I am getting quite comfortable on the Z and have been gradually increasing my speed as a result, it led to me asking questions regarding the limits of the wheel. Tbh I am extremely cautious at speeds above 22 or so mph due to being absolutely paranoid of a faceplant. This has resulted in me asking questions and I have had some excellent feedback from those on the forum who have far more technical know-how than I do. A subsequent post in an unrelated thread was just as interesting but I didnt want to de-rail the thread. Its where our esteemed @palachzzz posted the below:

"So.. Using this data, I derived a very simple overlean formula: Overlean speed ≈ rotation speed * 0.8,
MSX84: 78*0.8 = 62.4 
MSX100: 93*0.8 = 74.4
Nikola100v: 83*0.8 = 66.4
Monster100v: 91 * 0.8 = 72.8
Tesla84v: 69 * 0.8 = 55.2
Ninebot Z10: 81*0.8 = 64.8
Ninebot Z6: 61*0.8 = 48.8
Surely it does not take into account the load, slope, and is valid only for an almost fully charged wheel. Therefore, it is a very rough estimate, but it allows you to roughly understand the capabilities of each wheel, "

Its interesting to see that the lowly Z10 with its puny 58.8v has a higher overlean speed than the 84v MSX and 84v Tesla, and is only just below the 100v Nikola.

Yes I am only possibly provoking here and the figures are not concrete, but it may explain why the Z feels rock solid at or near the top speed. I assume the top speed of the 84v MSX is higher (35mph?), yet on paper, the suggestion is that the Z has more in reserve than one may assume at first, based on its voltage. It appears that Ninebot has not only restricted the Z top speed but in fact the wheel has more in reserve than the MSX even if it was indeed run at the same top speed. On the face of it, it seems the Z has gained safety from both angles.

It it just simply the case that Ninebot are more conservative than GW in terms of safety? If so, I am very happy with this. At this point in my euc journey I would happily take safety over anything else, and it seems that Ninebot have really restricted the Z top speed to achieve this, not to mention the throttling starting at 50% battery.

I guess the point of this post was for me to not only thank the guys with knowledge, but for me to get a better understanding of how close to the edge the Z is at top speed. I am getting the impression that its actually got a fair bit in reserve to maintain balance, but of course its fully appreciated that any wheel can be overleaned/pushed to the max due to terrain etc.

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1 hour ago, Planemo said:

It it just simply the case that Ninebot are more conservative than GW in terms of safety?

Yes, but exercise caution, please. The Z10 is far easier to overlean than an MSX, especially at speeds over 25 mph. I have never overleaned my Z10 but have come close twice. I have found the Z10 gives a warning pulse/dip just before its limit. I've felt it twice and was very thankful for it. Unless you are very sensitive to the "feel" of your wheel, it is easy to miss this final warning and lean right through it and into the pavement.

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Well received.

I presume this 'dip' occurs after both the beeps and tiltback?

And how is the Z10 easier to overlean than an MSX if the overlean parameters (pro rata) are lower? Not doubting you, just trying to understand.

Edited by Planemo

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@Planemo, well... EUCs have two general type of overlean:
1. by speed (that's something described in first post)
2. by torque 

First is pretty clear, no matter how powerful the motor, controller and battery are, the motor cannot spin faster than it can. In some point it will provide not enough torque, that will lead to overlean. This is what the numbers in the first post are about. Thats absolute maximum that cannot be exceed with such motor and such battery voltage.

The second one - it's much more complicated to describe for each wheel. It depends on slope, weight, wind, acceleration, etc.. a lot of things which leads to increase battery current. And in general the maximum possible current depends on speed (at higher speed - less possible current may flows throw the motor), that's about @Chriull 's graphs. 
Also current may be restricted by software, like Ninebot Z, Inmotion and KingSong. That's all makes everything difficult to explain, but.. Generaly gotway wheels are more powerfull, that's why it is much more hard to overlean gotway wheels on speeds [max speed] - [10km/h]. So, it is almost impossible to overlean MSX84 at speeds less than 50km/h (fully charged). But due software limitation of current in Ninebot Z10, I can overlean it at any speed, even at almost zero speed.
So, if you choose MSX100 and will not exceed 60 km/h (full charge, and.. about 45km/h at zero charge) - you will be much more in safe, than using Ninebot Z10 at any speed at any charge. 

Edited by palachzzz

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Thanks.

So from what I am understanding, Ninebot have indeed been conservative with the speed side of things, presumably for safety, but have restricted (relative to GW) the current levels. And is this a direct result of Ninebot only being 58.8v?

Reading between the lines it seems that the Z motor is cabable of giving a fair bit more than it does, but cant because of the wheels current limits. Presumably because the lower voltage requires a higher current and therefore its a vicious circle.

I do wonder whether NB could have specced down the motor to reduce weight whilst still having the same (if not more) safety margin that GW uses.

There seems no point in running what seems to be a very capable motor if the rest of it cant keep up?!

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Posted (edited)

Forget about 58.8v.. 
Limitation of NB speed is pretty reasonable for battery which installed in Z10 (pretty poor). Nominal battery current - 60A, but the limit is about 110A, it is almost twice overcurrent for battery, that's why it's pretty reasonable from different points of view. 
Lately I got burnt bottom Z10 board, and realized that Motor phase "C" FETs are burned at all (4 pcs), it makes short circut for the battery input, but.. nothing else were burnt. So it seems Z10 BMS has overcurrent protection, so, I think software limitation of current implemented in BMS. 
Such capable motor installed in Z10 to mitigate possibility of speed overlean (it is not possible in any charge on stock firmware). That's good point. 
Like if you choose MSX 100v and set tiltback at 48 kmh

Edited by palachzzz

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On 9/27/2019 at 1:32 PM, Planemo said:

Reading between the lines it seems that the Z motor is cabable of giving a fair bit more than it does, but cant because of the wheels current limits. Presumably because the lower voltage requires a higher current and therefore its a vicious circle.

 

As for GW a ~90A alarm is saving the mosfets/wires from going up in smoke, ninebot Z10 has the current limit at 110A. But still enough components burn:

16 minutes ago, palachzzz said:

Lately I got burnt bottom Z10 board, and realized that Motor phase "C" fets is burned at all (4 pcs), it makes short circut for the battery input, but.. nothing else were burnt. So it seems Z10 BMS has overcurrent protection, so, I think software limitation of current implemented in BMS.

Most probable both: current limit in firmware and overcurrent (shortcut) protection in the BMS.

As the Z10 has some (more or less ?if at all?) comparable lift cut of speed as the MSX84V this means, that they have different kv motors. The Msx motor reaches the speed with 84V, the Z10 with 58.8V. So the kv is about a factor of 84/58.8~1.4 bigger (Z10 to MSX84). By this the current to torque constant is about the factor 1,4 lower. Meaning that the Z10 needs about 1,4 times the current for the same torque as the MSX. (if they have different max no load speeds the figures change accordingly :P)

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4 hours ago, Chriull said:

As for GW a ~90A alarm is saving the mosfets/wires from going up in smoke

Pretty conservative :)
GW use phase currents, it gives almost nothing. 210A-220A is the absolute maximum for measuring of MSX/Monster mainboards, and about 160A for Tesla board. This currents in logs doesn't means burning. I have seen a lot of logs with numbers 210A + and all of them still alive. Most probably the real currents may be more... (not measured). But I have log with burnt monster at current 170A

 

4 hours ago, Chriull said:

As the Z10 has some (more or less ?if at all?) comparable lift cut of speed as the MSX84V this means, that they have different kv motors. The Msx motor reaches the speed with 84V, the Z10 with 58.8V. So the kv is about a factor of 84/58.8~1.4 bigger (Z10 to MSX84). By this the current to torque constant is about the factor 1,4 lower. Meaning that the Z10 needs about 1,4 times the current for the same torque as the MSX. (if they have different max no load speeds the figures change accordingly :P)

That's right. 
MSX84 rotate speed - 78km/h
Z10 - 81.5 km/h
Z6 - 61.5 km/h

 

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On 9/26/2019 at 8:28 PM, Planemo said:

Tbh I am extremely cautious at speeds above 22 or so mph due to being absolutely paranoid of a faceplant

I ride mine regularly at 23-26mph without issues (my cruising speed without paying attention to how fast I am going seems to be about 23, going up to 25 on some parts). I do keep the battery charged up and try to stay away from 50% and lower. But then again, at 50% you get speed throttling anyway, starting at 25mph for 50% battery and going down from there.

For me it feels as a pretty safe wheel as long as you stick to those speeds and don't go pushing through the throttle warnings < 50%. Of course don't go curb jumping at 25 :D 

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Sounds like you ride similar to me, I've not had any issues either. It does scare me though when palachzzz states 'I can overlean it at any speed, even at almost zero speed'.

I can only assume that I ride somewhat more timidly than our brethren do!

So it seems the Z is pretty good at not cutting out due to rotational speed, its only an overlean due to insufficient current which is likely to cause issue? So the main thing to remember is no big leans (or kerbs/bumps etc) at high speeds? This is the same for pretty much all wheels isn't it? :blink:

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17 hours ago, Planemo said:

It does scare me though when palachzzz states 'I can overlean it at any speed, even at almost zero speed'.

 

 

 

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17 hours ago, Planemo said:

It does scare me though when palachzzz states 'I can overlean it at any speed, even at almost zero speed'.

That's doesn't means that I can't ride without overlean. I realy like Ninebot Z10, I rode different wheels during this summer (18XL, V10F, GW Tesla) about week on each (~350 km) on each, and rode about 1000 km on GW Tesla when my Z10 was burnt. Also I tried 16X, MSX.. I feel advantages and disadvantages of each wheel.. But as result, I bought the second Z10 for the mean time until I repair my first Z10 :)
But, I can't say that Z10 the best, or the safest wheel, because it isn't true.

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5 hours ago, palachzzz said:

But, I can't say that Z10 the best, or the safest wheel, because it isn't true.

To be honest I wouldn't expect you to either, I had assumed that the more modern, humungous-batteried, monster-motored wheels would be the safest.

Good vids showing the overleans, not seen anything like that before on any wheel at those speeds. I actually thought the top vid was due to wheelspin in the mud at first!

I might actually try it on grass from a standstill, just to feel what an overlean is like, never having had one before. I imagine it's as scary as hell at 25+ mph.

I'm not sure I will actually be able to do it. My in-built 'oh-shit-o-meter' nearing the red zone might prevent me from trying as hard as you were! 

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