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KS16X Cutoff/Overlean - 29-30mph

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1 hour ago, RockyTop said:

An average of 3%  for a mile. 

As I said, everything was going against me at the time. I never heard a beep ....... but I had my ears covered because of the cold. Now I pay attention to all of the factors and I got a much loader beeper flush with but outside the wheel. I am not sure that it ever did beep but I know that I would not have heard it anyway. 

With a summer riding weight of 65kg I get the 5 beeps on my 84v MSX at slightly over 48kmh at exactly 50% battery.
Your wheel must have been beeping like crazy unless it's a 100v.

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9 minutes ago, Mike Sacristan said:

With a summer riding weight of 65kg I get the 5 beeps on my 84v MSX at slightly over 48kmh at exactly 50% battery.
Your wheel must have been beeping like crazy unless it's a 100v.

84V   You are probably correct. I would never have thought about doing what I did if I knew that the battery was so low. I had just got it off the charger after charging all night  I thought that it was at 100%. I never checked.......  Come to find out the cord had come unplugged from the brick. It had not charger at all from my last long ride.

Edited by RockyTop

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58 minutes ago, Chriull said:

So there is no "three kilos extra" for an 100kg rider at a 3% slope. "Just" the thrust is needed to lift the 100kg + the wheel against gravity at a certain rate, which is determined by the slope percent and speed.

Speed? I was in the belief that I had learned from one of your previous posts (and even had understood) that the needed thrust does not depend on the speed. That's why zipping up the hill at speed zero is so terribly inefficient, all the thrust for nothing.

BTW, isn't the thrust that is needed to lift the 100kg along the 3% slope (almost) exactly the 3kg = 100kgx3/100 thrust that @Aneta mentioned? Too late at night...

Edited by Mono

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2 hours ago, Chriull said:

At a flat road there is just thrust needed for acceleration friction, air drag and self balancing. Zero thrust needed to lift some weight.

So there is no "three kilos extra" for an 100kg rider at a 3% slope. "Just" the thrust is needed to lift the 100kg + the wheel against gravity at a certain rate, which is determined by the slope percent and speed.

Yes, 3kg extra thrust is needed compared to the same conditions on flat road, I meant it exactly this way.

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Damn! That overlean really seemed to come out of nowhere. I'm glad you came away from it uninjured.

I really don't like riding on roads like that. The bike path is narrow and positioned right next to cars going 35+mph which gives the illusion that you're going much slower than you really are. In situations like that I hit my first speed alarm (currently set at 26mph) much quicker than normal.

Thanks for sharing your logs. Every data point helps better understand this wheel's capabilities. Guess I'll be keeping my alarm on the conservative side for now.. 😜

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When i check facts without any bias just can have this conclusion:

1. It is not overlean because of loose power. According to telemetry 843 W and 10,7 A so or telemetry is wrong or there is other hardware related problem which leads to worst case scenario and cutout.

2. As i mentioned in other post about firmware 1.07 i feel that 16x  gaves more power and acceleration in range 43km/h - to 47 km/h ( I dont ride faster 47) but less in range 0-to 43km/h. With FW. 1.05 i need a lot more efforts to accelerate from 43km/h to 47km/h  but it has super acceleration from 0 to 43 km/h. My guess that feeling that you can accelerate faster in upper speed range mislead rider about technical capabilities of wheel. It still same KS16x hardware and firmware cant change its technical capabilities in upper side. 

Suma sumarum I think FW 1.05 power management was nearest 16x technical capabilities. Just had some issues with riding in low battery levels.

Disclaimer: I am happy Ks16x rider with at the moment FW 1.05 and ~1000 km experience with it.      

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14 hours ago, Mono said:

Speed? I was in the belief that I had learned from one of your previous posts (and even had understood) that the needed thrust does not depend on the speed.

Yes and no.
For going on a flat road there is no thrust needed for a constant speed. (Just "in real" life some thrust is needed to overcome friction, air drag and support the self balancing.)

For going up a hill with constant speed (without friction, air drag, etc...) thrust is needed to overcome the gravitational force (in "vector arithmetic").

 

Quote

BTW, isn't the thrust that is needed to lift the 100kg along the 3% slope (almost) exactly the 3kg = 100kgx3/100 thrust that @Aneta mentioned? Too late at night...

Your almost is the key - the hypotenuse of the slope is the way one takes while "overcoming the kinetic Energy". If one approximates the hypothenuse with the "adjacent side" one gets to this "100kg * 3% = 3 kg"

Edit: ... and this approximation is of course fully appropriate for the slopes we normally ride with EUCs, especially once one looks at something around this 3%...

13 hours ago, Aneta said:

Yes, 3kg extra thrust is needed compared to the same conditions on flat road, I meant it exactly this way.

Yes. Was just "irritated" yesterday night by your comparisson of driving on a flat road which needs (ideally) no thrust with going up a slope which needs thrust to overcome the gravitation - that's in two different drawers of my brain :)

Edited by Chriull

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3 hours ago, skautas2003 said:

When i check facts without any bias just can have this conclusion:

1. It is not overlean because of loose power. According to telemetry 843 W and 10,7 A so or telemetry is wrong or there is other hardware related problem which leads to worst case scenario and cutout.

If one looks at the voltage it seems to raise from ~78V to ~81V. With an 20s6p pack with ~30mOhm per cell and so a total internal resistance of ~0.1Ohm - so for this 3V voltage difference some 30A battery current must have flown.

Of course (unfortionately) this graph is very condensed and it is hard to see the real details :(

Even with the original csv log file it is hard to get into too much details - the sample rate is not too high...

It was already nothing really to be seen with the original logs from the "pedal tilt by ankle flip" - seemed to be nowhere near the limits, but with the low sampling rate nothing definite can be concluded :(

Maybe here with the original logs one could see if this was an overlean (near the limit) or "firmware misbehaviour"...

 

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i thought that you had a cup of coffee in your hand.  Glad you were fully armored.  I would back the audible alarm back to 25 mph if I had a 16x.  

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18 hours ago, Aneta said:

When speed is too close to "terminal", the wheel physically cannot do a tiltback, because for that it needs to spin faster under the same load to get ahead of the rider, but it can't, because the thrust margin is already pegged at near zero. Fully expected.

so more thrust is the ultimate solution?? 

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4 hours ago, Chriull said:

Yes and no.
For going on a flat road there is no thrust needed for a constant speed. (Just "in real" life some thrust is needed to overcome friction, air drag and support the self balancing.)

For going up a hill with constant speed (without friction, air drag, etc...) thrust is needed to overcome the gravitational force (in "vector arithmetic").

How does it depend on speed then?

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1 hour ago, Afeez Kay said:

so more thrust is the ultimate solution?? 

Motors have a set speed before the emf balances out. Once the balance is achieved no more speed is available.  The closer to balance you get the less possible torque is available. In this case it appears that the top speed of the motor is too close to a balanced emf reducing the torque below what is needed at 30mph.  If the tire diameter were larger the motor speed would be slower and the available torque would be greater so long as the motor can handle the amperage.  ............. 18XL

If this is correct in this situation. The solution would be a bigger diameter tire, higher voltage battery or rewinding the motor to fit the need.

Edited by RockyTop

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31 minutes ago, Mono said:

How does it depend on speed then?

It does not. Changed the previous post accordingly.

It was just the power (why i mixed it up :( ), but thrust/speed depends only on force and slope %.

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5 hours ago, Chriull said:

It does not. Changed the previous post accordingly.

It was just the power (why i mixed it up :( ), but thrust/speed depends only on force and slope %.

FTR then, for any inclination angle, with the abuse of equating mass and force, we have

added_thrust_demand = vehicle_weight * sin(inclination angle)

right?

EDIT: replaced tanh with sin

Edited by Mono

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16 hours ago, Aneta said:

By the way, the numbers for current and power as shown in OP seem to be suspiciously low. As can be seen from Motor Sumulator, the mechanical power at speeds ~50kph is around 2kW, while battery power is in the upper 2000's, closer to 3kW:

I think that numbers are OK and they are real measured values. They just represent limited torque available at near max speed of this motor/battery configuration. Overlean is a consequence of having no torque margin. Of course EUC World graphs shows filtered values for better readability, so any spikes will be filtered out, but this shows general rule - current goes down when approaching physical speed limit of motor. I have looked into EUC World database and also KS-18L/XL wheels doesn't draw significant currents near their top speed. Numbers are very similar. Currents tend to get high mostly during acceleration with low or moderate speeds, also max current values are observed in middle speeds about 20 mph. 

16 hours ago, Aneta said:

I'm afraid using this tool to estimate operating condition of KS-16X is pointless and proves nothing. Without knowing details about motor construction we cannot get reliable values that has any meaning. Just change motor type from M3540 to M3525 and you'll get result showing that it's even impossible to reach 30 mph.

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4 hours ago, Joker10 said:

i thought that you had a cup of coffee in your hand.  Glad you were fully armored.  I would back the audible alarm back to 25 mph if I had a 16x.  

1 hour ago, Duf said:

Falling with a coffee cup in hand, what idiot would ride while drinking coffee????  ;)

Bahaha! That's my 3D printed enclosure for this horn: https://www.amazon.com/Innovative-Lighting-545-2010-7-Yellow-Electric/dp/B002IV8RFY/

Coincidentally, I do love a good coffee. Now, if I could get a functioning espresso machine onto one of my wheels, that would be one fast espresso!

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24 minutes ago, Mono said:

FTR then, for any inclination angle, with the abuse of equating mass and force, we have

added_thrust_demand = vehicle_weight * tanh(inclination angle)

right?

times g . But maybe this can be dismissed if talking about thrust in kg and not force in newton? 

Ps.: The h after tan is a typing error? The slope percent is just the "normal" tangens.

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4 hours ago, Chriull said:

times g . But maybe this can be dismissed if talking about thrust in kg and not force in newton? 

yes, thrust in kg which means not multiplying by g

4 hours ago, Chriull said:

Ps.: The h after tan is a typing error?

no, but it should have read sin :rolleyes:

Quote

The slope percent is just the "normal" tangens.

I see, you also don't have a plan :cheers: The tan goes to infinity for 90º, so that can't possibly be the right correction factor for needed thrust to lift weight.

Edited by Mono

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2 hours ago, RockyTop said:

Motors have a set speed before the emf balances out. Once the balance is achieved no more speed is available.  The closer to balance you get the less possible torque is available. In this case it appears that the top speed of the motor is too close to a balanced emf reducing the torque below what is needed at 30mph.  If the tire diameter were larger the motor speed would be slower and the available torque would be greater so long as the motor can handle the amperage.  ............. 18XL

If this is correct in this situation. The solution would be a bigger diameter tire, higher voltage battery or rewinding the motor to fit the need.

So would a 100v system be a solution?

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11 minutes ago, fryman said:

So would a 100v system be a solution?

For some yes. But many riders would just go faster and/or accelerate harde and then faceplant again... :(

28 minutes ago, Mono said:

I see, you also don't have a plan :cheers: The tan goes to infinity for 90º, so that can't possibly be the right correction factor for needed thrust to lift weight.

The thrust = m * slope_in_% = m * tan(inclination angle) is only an approximation for small inclination angles, where the adjacent side is used instead of the hypothenus.

The correct formula would be:

Thrust = m * Delta h / sqrt(Delta h ^ 2 + Delta s_horizontal ^ 2)

Edit: or to make the calculation with the angle the sinus would be sufficient.

28 minutes ago, Mono said:

I see, you also don't have a plan :cheers:

In regard to the hyperbolicus functions - a clear yes!

I just took a short look at wikipedia at this functions - i decided i'm also very happy without having a plan! :cheers:

Edited by Chriull

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1 minute ago, Chriull said:

For some yes. But many riders would just go faster and/or accelerate harde and then faceplant again...

It seem KS is having a hard time dialing in this new 2200W motor. 

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3 hours ago, Mono said:

FTR then, for any inclination angle, with the abuse of equating mass and force, we have

added_thrust_demand = vehicle_weight * tanh(inclination angle)

right?

No, it the sine, not tangent of angle:

T = mg*sin(angle)

% grade is the tangent of the angle, however, so if one prefers % grade, thrust due to gravity is:

T = mg*sin(atan(%grade))

But for small angles, sin and tan are very close, and equal to angle itself, expressed in radians (sin(x) ~= tan(x) ~= x when x -> 0):

T = mg*(%grade)

For example, for 3% the precise thrust is 2.9986kg, but 3kg is good enough. For 20%, it'll be 19.6kg, not 20, but ballpark 20 is also GE for rough estimates. For San Francisco's steepest street, 41%, the diff will be more substantial: 37.9 vs 41.

 

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4 hours ago, Seba said:

I'm afraid using this tool to estimate operating condition of KS-16X is pointless and proves nothing. Without knowing details about motor construction we cannot get reliable values that has any meaning. Just change motor type from M3540 to M3525 and you'll get result showing that it's even impossible to reach 30 mph.

All direct drive BLDC motors have the same construction, and once you find a motor from the list that gives reasonable results, it can be used for illustrative purposes. Yes, exact numbers can be different in real life, but the trends are the same. One can also choose Custom Motor and enter custom parameters that better match the motor on hand.

EUC motors are nothing but ebike motors. No EUC manufacturer is making or even designing their motors (with, perhaps, exception of IPS?), they simply order them from big factories making all kinds of ebike motors, with small customizations like axles.

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2 hours ago, fryman said:

So would a 100v system be a solution?

It would seem so, see:

- but due to risk homeostasis, the riders will be riding at proportionally higher speed where margins will be getting thinner even faster (because of quickly - quadratically - growing air drag), and spills will be more injurous. Only artificially throttling 100V system to have max speed of 84V system would give thrust advantage.

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