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Master Ong

Unlocking Speed for Rockwheel Gt16

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I tried on Darkness Bot and it said it did not manage to apply. I download the Rockwheel app and didn't see anything in there. What have you guys done to unlock the speed?

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Simply go to Rockwheel app's tiltback settings and set the tiltback to the speed you need... 

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17 minutes ago, s.m. said:

Simply go to Rockwheel app's tiltback settings and set the tiltback to the speed you need... 

Thats it? And Max Speed can go up to 28mph/ 45km or more?

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For me - at a weight from 65kg - 45km/h is a safe speed with a (little) power reserve where the wheel can handle unexpected bumps or potholes. 

My setting: 45km/h = 3rd alarm and tiltback = 46km/h

I reach my tiltback on smooth surfaces and when the wind noise is too loud, only. Normally I respect the last beep.

But when the battery is on the last LED after a long trip, I go max. 40km/h without pushing too hard and less pushing uphills, too. 

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So far I only clock 22mph/ 25kmph but also I wasnt wearing any gear.

I also just want to know out of curiosity whats the top speed of my 858Wh 1036Wh. 

Also can someone explain to me why theres two numbers 858Wh and 1036Wh?

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9 hours ago, Master Ong said:

I also just want to know out of curiosity whats the top speed of my 858Wh 1036Wh. 

There is no such thing as "top speed" with an EUC :ph34r: - one needs at least one more parameter, the burden which the wheel has to overcome. With the lowest burden (just the friction of the axle) on can reach the lift-cut-off speed (the maximum speed reached, if one lifts the wheel up, slightly tilted forward so it spins up).

The more burden the wheel has to overcome (incline, acceleration, wind, ...) the lower the maximum reachable speed will be. The battery condition has some influence, too - the more charged the battery is (higher voltage) the higher the speed will be at a certain load.

This looks somewhat like this following graph (ignore the numbers - this is not made for the GT16 and your number will be different)

The left, vertial axis shows torque (== motor current) and the lower, horizontal axis shows the speed.

The green and blue lines (Max Values for Max Batt and Max Values for Min Batt) show the limits for fully charged and empty battery. The motor can _never_ reach an operating point "outside" (above and to the right of the limit line, grey filled area in the second graph) of this limit lines.

Were these lines meet the Speed axis is the absolut maximum reachable speed (no load speed). This is more or less the lift cut off speed.

The light blue line shows the set tilt-back speed, which is not (easy) to overcome, the violet line shows some internal current (== torque) limit for low speeds to protect the motor coils and the electronics.

(In this  example the red line shows the motor current (== torque, burden) logged from some drive - it was always well inside the limit (no overlean))

4sXUrSA.png

Here the next graph (actual, "quite correct" numbers for a KS16C) to dig a bit more into "details". Here are three different "acceleration/incline" lines drawn (different shades of violet) (again please ignore the numbers for incline degrees and acceleration - they are unfortionately wrong ;( ). They are for an acceleration from standstill and show the needed motor current (== torque the motor produces) while speeding up.

7918cNC.jpg

Here the darkest violet line shows some slow acceleration - with this wheel while accelerating one will just reach the tiltback at 30 km/h and everything is fine. (The line should stop at the tiltback and not continue to the right in a "perfect" chart :D)

Looking at the lightest violett line - this shows an "insane" acceleration (or acceleration up an incline) with which one will "hit" the limit. The limit are the blue lines - the actual limit is determined by the battery voltage (~battery charge). The motor cannot proceed along this light violet line (The torque needed to go on accelerating and balancing the driver) - the motor is "forced down" along one of this blue lines and by this produce less and less torque -> the rider falls forward. With this high acceleration this will definitely feel like a cutoff and send one flying without a chance to react and no prior warning. Maybe the 80% alarms/tiltbacks of GT or GW wheels will beep/start to tilt just before the crash...

If one looks at the middle ("medium light" violet) line which show some "medium" acceleration, things start to get more "suspenseful/complicated". Depending on the battery charge it could lead to an accident or just normal operation. With ~53% battery charge (dark blue limit line for 58,97V) one will hit the limit before tilt back sets in and overlean without prior warning. With the other two limit lines (lighter blue 61,84V ~70% charge and 67,2V == 100% charge) one gets the tiltback and nothing happens! Just with the medium blue line (61,84V ~70% charge) if one decides to "ignore" the tilt-back and ride with the pedals tilted one could reach this limit and overlean and have an accident, too.

So what does this limit lines mean - whats the consequences of "touching/hitting" this lines:

If one is accelerating and by this leaning forward, the wheel has to accelerate to follow the center of gravity to balance the rider. For a constant acceleration the needed torque (motor current) is slightly increasing the higher the speed gets (in because of the wind resistance). Once one "touches/hits" the limit line the motor cannot provide anymore the needed torque  (instead of following the violet line, the motor is "forced" to go "down" along the blue limit line). So as one is still accelerating (leaning forward) and the motor starts to provide less an less torque but the rider still needs the same slightly increasing torque to be balanced in his forward lean -> the pedals dip forward and one "rotates" towards the asphalt! The stronger one is accelerating the harder this transition will be felt - until it "behaves" like a cut off. If one is just slightly accelerating with little lean one could feel the pedal dipping and react (leaning back and by this decelerating) so one comes well "inside" this limit line again and just drives on.

So here the last graph with a real world example of an overlean logged with wheellog on an KS16C (green line). From each green arrow to the next it's about 0,2 seconds (KS wheels transmit about 5 values per second). In the beginning there is some "nice" acceleration from ~8 km/h, inbetween a bit less acceleration at around 20 km/h, then the driver again accelerated stronger until he hit the limit (for 58,97V which is ~53% battery charge). One sees nicely how the green line is forced down the blue limit line sending the rider down. Without any prior warning by beeps or tiltback...

R6iNpPS.jpg

These were till now all just examples/explanations for "active" rider actions without external influences - in a real world there are uneven road pieces (bumps, holes) which with their "small" inclines and additionally the longer way the wheel has to go compared to the rider mean higher burdens (torque == current) for the motor. Also wind gusts, little imbalances from the rider, etc, etc can, if one drives somewhere too near to the limit bring the motor instantly to the limit leading to an overlean. This "dangerous" area is more or less the triangle between the tiltback, the limit line and the speed axis - if one disables the tiltback (or the higher one sets the tiltback) the more "possibilities" one has for high speed crashes...

 

 

Quote

Also can someone explain to me why theres two numbers 858Wh and 1036Wh?

There are two versions with different battery configurations - one has 858Wh and the other one 1036Wh. As i googled this and have found some alibaba offers for "84 v Rockwheel GT16 858Wh 1036WH" one can choose there different colors and the different battery capacities.

As the GT16 is a 84V wheel it has 20 cells in series. With a nominal cell voltage of 3,7 Volt, 4 cells in parallel and 2900mAh capacity per cell one comes to this 858Wh (3,7 x 20 x 4 x 2,9).

With 4 cells in parallel and 3500mAh per cell one get the 1036 Wh (3,7 x 20 x 4 x 3,5).

Some additional detail in regard to the above graphs - how the battery configuration (capacity) influence this limit:

- The less capacity, the faster the voltage decreases and by this the faster the limit is shifted to the left.

- Battery packs with less cells in parallel have a higher internal resistance. The steepness of the limit line is determined by the resistance of the whole circuitry (mainly the internal resistance of the battery and the motor coil resistance, beside the wiring, connectors, Mosfet on resistance, etc...) with the "fix point" beeing the no load speed at the speed axis. So with a battery pack with less parallel cells one has a "flatter" limit and with a pack with more cells in parallel one has a "steeper" limit line.

Imo (i have no real sources for this) colder batteries also behave like/have a higher internal resistance and flatten the limit line, i'd also assume that batteries with lower charge (and or just were "stressed" by higher discharge currents) also tend to have a higher resistance and so not only the limit is shifted to the left, the line also "flattens". But as said, this are assumptions/"wild speculations" from my side were i am missing reliable sources/numerical and reproducable real world experiences.

 

Edited by Chriull

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Man, you make me feel dumb Chriull....hehe!

thanks for all this knowledge.

the next time i buy a wheel i will send u the specs so u can do these calculations for me and i will carry the graph and limit the wheel accordingly, hehe! 

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