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Chriull

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Everything posted by Chriull

  1. Kingsong 16 S, what set up do you use?

    Its your riding experience - so try them out snd what you like most. I'm mostly in players mode and tried from time to time riding mode cause quite some people stated that this should be better to accelerate up inclines...
  2. Anatomy of an overlean

    Just got the wheellog data from another rider of an "high-speed crash" he had with his KS16B some time ago. (1) He heard no beeps and there was no tiltback - they wheel just stopped supporting him... The speed and current (dark blue line - IMotor KS16C) in the limit diagram: One sees nicely how he "hit" the motor limit (violett line) at around 27 km/h - 36A and continued on this limit line until about 36 km/h. So tiltback would have started at 30 km/h - but not anymore possible since the motor was at it's limits. It just should have beeped by then - but quite imagible that this was not heard anymore after beeing in the process of falling and seeing the street coming nearer... The wheellog data (speed,voltage,current,temp - the rest is calculated..): I had to adjust some motor constants a little bit to get the calculated limit line to his measured one (my first try was some real rough estimation (http://forum.electricunicycle.org/topic/7549-current-demand-versus-battery-voltage/?do=findComment&comment=106424)) For the internal resistance of the battery pack (16s4p LG MJ1) i have now 0,23 Ohm instead of the calculated 0,148 Ohm. I got this by minimizing the "ripples" of the calulated no-load battery voltage (U Batt 0) as low as possible... The still nicely seeable peaks on U Batt 0 are from the regenerative braking - the motor current is always measured as positive value and the used formulas are not right for the "regenerative" case.) R Coil was changed to 0,37Ohm and kv to 1,41 V/km/h. (1) he "just" got some nasty road rash/bruises and recovered fully. Ps.: Had some interesting reading about that the coil temperature has quite an influence on the motor charateristic - copper increases it's resistance roughly about 0,4% per degree celcius - so between 20 and 80 °C is a difference of 24% in resistance of the coils! And this resistance is one of the main parameters for the "steepness" of the limit line. PPS: he refused to repeat this with his KS16S so i get data for our new wheels...
  3. Anatomy of an overlean

    @Jason McNeil and all the other resellers with good contacts to the manufacturers - maybe this time to overlean calculation would be something to show to the manufacturers and gently "force" them to implement this into the firmware for tiltback/beeps?! As shown this is nothing magical or complicated to calculate and they should know all the needed values of their wheels. Edit: They also could use this method to eleminate at last the "tiltback of death" - if one accelerates like crazy the tiltback sets in at max speed within tenth of a second and vault the rider of the wheel. With the known acceleration the firmware knows that the max speed will be reached in 1-2 seconds and can already start earlier with a soft tiltback.. And with the much higher internal sampling rate of the firmware they know the acceleration much more precise and accurate than with the wheellog samples...
  4. Anatomy of an overlean

    Here one gets time to overlean t as t = (I_motor_current - I_max - k * v) / ( k * a ) for (a >= 0 ) with k = - I_max / v_max_no_load This time to overlean (black line) looks in the charts like this ( for a>0, limited to max 10 seconds), values in seconds on the right axis (i forgot to change the axis label from Power W to time (s) ): Seems to be a very valid and usefull warning indicator! Also the acceleration is included (green line, shows 10 times the acceleration in m/s² on the left axis, negative values set to zero) - is a very "instable value", but imho averaging won't help too much since the sampling resolution is already 0,2-0,3 seconds and every averagin will delay the warning further untill it warns once one lays already on the ground.... And for an accident free part of the ride:
  5. Anatomy of an overlean

    My original intention was to implement such an alarm in wheellog - as it seems it took from July 25th till now to make an first try in excel ... So as @palachzzzis quite active developing wheellog, maybe he or some other member here could easily overtake me How to achieve this alarm: First step is to obtain the current (==torque) over speed limit. For this one needs the maximum speed without load. A first approximation is to take the lift cut off speed and add a little bit... This maximum speed gives one the motor constant kv (battery voltage == motor voltage at this speed, so maximum speed divided by the battery voltage gives kv) A little bit more complex is to obtain the slope of this line. My first attempt was to take @EcoDrift's measured max output power (http://airwheel.ru/test-monokoles-na-dinostende/) which would be for the KS16C about 2,2kW and lean the line from (current=0, vmax) to the "current for max output power of 2200W" line in the graph. But as one sees easily from the wheellog measurements this would lead to a limit which is already way outside of the limits! My (so far) explanation for this: - @EcoDriftmade the measurements with an "cold" motor. Copper increases its resistance from 20°C to 80°C by ?20% or 40% (don't remember exactly)? and the coil resistance is one of the main factors of the slope of this limit line. - the second important factor for the slope of the limit line is the internal battery resistance. This is, from what i read so far a quite "complex" value - quite varying by the chemistry "changes" by the historical load situations... - Maybe the coil resistance is in dynamic situations not a constant ohmic value, but also the inductance is to be considered? (and also the inertia of the system which reacts like an inductance?) - accuracy of the data send by the wheel to wheellog... So the best compensation for all this was that i got the wheellog logs of this overlean - by the logs one gets directly the limit line and by this v max at no load and the slope of the limit line (internal resistance battery and motor coils). (2) So then the last step from the logs would be to split up the internal total resistance to the battery and the motor coil part. This was done by me just by calculating the "ideal" Battery voltage (U_battery_0) and by changing the value of the internal resistance to get a smooth graph (least deviation...). Is not the nicest method, but i could not think of an other way till now... Used formulas: Valus delivered from wheellog: U_battery, I_motor, v (speed) Values to be determined for each wheel: kv, R_internal_battery, R_coil U_back_emf = speed * kv P_motor = I_motor * U_back_emf + I_motor * I_motor * R_coil (consumed power by motor) ( P_motor_output = I_motor * U_back_emf) I_battery = P_motor / U_battery U_battery_0 = U_battery + I_battery * R_internal_battery ( ideal battery voltage ) v_max_no_load = U_battery_0 / kv Now the actual torque speed limit line is described by: Current axis endpoint (speed=0, I_max) and speed axis endpoint (v_max_no_load, current = 0) with I_max = U_battery_0/ (R_coil + R_internal_battery) (1) I_limit = - I_max / v_max_no_load * v + I_max Now with the actual acceleration a = delta v / delta t one can "look" into the future and get the speed within 2 seconds v_2secs = v + 2*a calculate I_limit with this speed and check if the actual motor current is already above this limit value. If so one can give the 2 seconds warning. I did not try till now to also calculate the current change rate and by this also extrapolate the future current... But an constant current means constant load (acceleration, incline) and a current change means a change in current and could by this be "overdone" and gives too many "false" alarms? My next idea is, to just calculate by the acceleration and acutal limit line in how many seconds the limit will be reached and plot this against the "normal" graphs so one can test "on paper" different methods... (1) Made a "small" fault with my posted diagrams before and used U_battery instead of U_battery_0 here... (2) unfortunately for this (by now imho the best method) one would need fearless testpilots which make some overlean logs for the different wheel... Ps.: As one sees in the graphs these formulas are not valid while regenerative braking!
  6. Anatomy of an overlean

    Tried it with nicer colors - the only really important stuff is the green line (motor current over speed) and the grey backgrounds (out of limit) And the normal graph over time: This time i added a first try prediction by the acceleration (speed difference between last sample and actual sample) if the limit will be reached/crossed within 2, 1 or 0,5 secs. This is shown with the "I>I limit" line, where a value of 20 means limit reached/crossed within 2 seconds, 40 within 1 second and 60 within 0,5 seconds (assuming acceleration and load stays the same). There was no averaging or flattening done by now - just the "raw" values. But seems to make sense by a first look... The one second alarm came ~2 *) secs before the crash (because he decelerated inbetween), then imedeately the 0,5 secs alarm started ~1,2 *) secs before the crash (because again the acceleration was reduced) *) Edit: The accident happened at ~18:15:01,7 (when the current and power went down) and not at ~18:15:02,4 when the speed went down... So the pre warn times are this ~2 and ~1,2 secs instead of the previous mentioned ~3 and ~2 secs... To compare the same chart for an incident free part of the ride
  7. WheelLog for Inmotion - Development

    Welcome! Depends if your phone supports Bluetooth LE - Android 4.1.x should support it from what i googled. You find the sources on https://github.com/palachzzz/WheelLogAndroid and you could try recompile them for 4.1 with https://developer.android.com/studio/index.html
  8. Kingsong 14c battery dead

    You shold get them from @1RadWerkstatt located in germany (kingsong diatributor and battery pack manufacturer). In france is also a big kingsong distributor and there are akso quite some still a bit closer to sweden (from whom i don't know the name...;( )
  9. Msuper v3 top speed crash - wrecked shell

    The "normal" voltage drop of a non ideal voltage source is considered (modelled by an ideal voltage source plus the internal resistance). But the additional voltage drop of batteries (by their chemistry) which partly recovers again not.
  10. InMotion V8 tried to kill me Suddenly

    You will notice once the battery is degraded by lower range and "sloppy" behaviour of the wheel. as @WARPed1701Dstated with normal full charged to discharged cycles one should get at normal temperatures about 500 full discharge cylces from the battery, which is quite a milage. But then the batteries are not dead - they should still have about 80% of their capacity! this lifespan can be greatly improved the longer the battery stays around ~30-50% charged - imho the amount of full discharge cycles then could be improved to some ten-thousands... but one takes the fun from driving with no range left by just pleasing the batteries imho more important is to not discharge the batteries and then let the wheel lay around too long (by the self discharge the charge gets really low until they are irrevocably destroyed) and the second worse thing is to store them fully charged at high temperatures. also very important is to balance the battery pack regularly by leaving the xharger plugged in for a couple of hours after the pack is already charged! But looking to treat the batteries right is just one thing - the other imho more important thing is to not accelerate too much at high speeds. From combustion engines we are used that they get loud if we rev them up to much. We know that we can destroy them by doing this and they really sound stressed if one overdoes this. And one also knows that there is no (real) acceleration anymore at high revs - but it does not matter since one has two or four wheels and nothing happens but one just keeps the speed... and noone would do this - making noise and destroying the engine is just crazy. electric motors have no problem revving up, one hears nothing - but the torque==acceleration gets less too - so no "internal" warning until one lies flat on the ground. They manufacturers implemented beeps and tiltback as warning, but if one accelerates (leans forward) strong enough this warnings come way to late or even not at all... there is much room for improvement and especially as you noticed this should be mentioned in the manual. So also with a fully charged new battery in perfect condition every wheel can be overleaned - its just easier with an empty battery... Overleaning with an msuper its much more daring and suicidal than with an airwheel but still no problem at all...
  11. InMotion V8 tried to kill me Suddenly

    Sorry - but this could easily be just a "normal" overlean... It's not a "good" but a valid reason... You were near max speed and accelerated... Could be, that by your experience and confidence it was just a bit more like before, maybe combined with a small incline or bump... (Edit: and/or maybe the battery a bit more depleted) If you'd have some logs like from for example the wheellog app one could analyze it further and maybe find the valid (real) reason. Edit: ps: strongly accelerating near max speed is in any case a bad idea, since it can kead very very easily to such an overlean.
  12. WheelLog Android App

    Wow - tiltback at 45 km/h can also be set for the KS16B? Imho that would lead more or less to a disabling of the tiltback - even with full batteries this speed could only be reached with very low load ( maybe just on a slight decline? ) as it is very near to the lift cut-off speed...
  13. What is your experience with the KS16S until now ?

    "Footplate resistance" is about comparable to my ks16b - i did not notice any real difference. Mine ks16s has no real "mechanical running noise" as my previous ks16b - imho i had a bit bad luck with it. @Blunzn's ks16b had not this kind of running noise. (And his ks16s has "none," too) My first impression of the high pitched noise was also that it is a bit less now - but after driving a bit it's definitely still here and from time to time imho maybe also a bit louder. Trolley handle is exactly like with the ks16b for me - never had any prob. +1 Never used them +1. they improved nicely the power and the stiffness/responsivness/driving behaviour. I also encounter no more/much less dipping forward driving bents. Would also be my impression - but i never measured this. Anyhow driving faster uses up the battery faster... another little thing - the 16s firmware reports also negative (regenerative) current now ... so for me a worthwhile uprade without any probs so far - maybe we can meet in vienna if you'd like some personal hands on experience edit: mine has firmware version 1.02
  14. Riding safe by WheelLog APP

    FYI this app was and is developed here by forum members:
  15. WheelLog Android App

    One would have to "just" multiply the battery voltage by the right factor - the 84V gw's just report if they had a 67V battery. I assume the battery voltage/wheel type is decoded somehow in the serial number/bluetooth name/or whatever? @Marty Backesince you have quite some gw wheels - can you identify any pattern?
  16. Ninebot One Z : Z6-Z8-Z10

    The gyro itself is mechanical - just the output is electrical and everything minituarized and put into an IC housing...
  17. Gotway ACM just died @ 30kph+

    So then according to http://airwheel.ru/test-monokoles-na-dinostende/ it should have ~2,3kw peak output power and about comparable to the KS16b/c with 2,2 kw peak? So battery was quite full and by this you had the "chance" to go faster at the accident - with a lower battery you would have fallen at lower speeds... So there seems to be no fault with your wheel - you just pushed it as hard as one could and reached the limits... If you look at the graph at my before posted link (http://forum.electricunicycle.org/topic/7855-anatomy-of-an-overlean/#comment-107721) and look at the the violet, green and red lines (max values for...) these show the limits. You can push your wheel as hard as you like as long as you stop within the limits (of course this graph is for another wheel, but it should give an rough idea...) Just in the low speed high current region you could melt some cables or overheat your wheel if you push it for too long.
  18. Gotway ACM just died @ 30kph+

    This quite presumably is no failure of the wheel - just an non advertised intrinsic property of each electronic motor: the higher the load (acceleration, going uphill) and/or the lower the battery voltage (roughly left capacity) the lower the maximum possible speed. Gotway advertices maximum speed for quite low load with full batteries - one has to adopt this downwards depending on load and battery state to still drive safely. Also other more restrictive wheels like the ks16b can be brought to an overlean (from most people called cut-out) without any prior warning: This intrinsic characteristic of electric motors leads to all the questions of the other posters here in this topic - to "reveal" if it was a "normal" behaviour of the wheel (which a new driver normaly does and cannot know anything about - even if one would read the manual...) or really some failure ... Unfortionately the wheels are not designed to take crashey at this high speeds. If you had good luck its just bend plastics of the cover which rubs - if you had bad luck it is, as already mentioned a "bend" axle or metalic frame part. The second case has to be replaced, for a plastic cover problem some tinkering should be sufficient.
  19. Ampers in WheelLog

    That current is the motor current (not battery current). For slow speeds that should be quite ok - but could lead to overheating going uphill like this for longer distances. for example on an ks16b (800w nimonal power) this amperage lead to an overlean at 27 km/h (http://forum.electricunicycle.org/topic/7855-anatomy-of-an-overlean/) - so how much safety margin you have depends on your battery voltage (charge state) and your speed. according to https://airwheel.ru/test-monokoles-na-dinostende/ your ks14b should have some max peak power of 1,1 kw with cold motor and full battery, so with some safety margin and assuming that batteries are most times not at full charge while riding some 6-700w peak power sgould be available quite at any time. this should enable you to ride up to about 15 km/h with ~30A (very roughly)
  20. New Kingsong APP (Android)

    It's not inluded by now - it still has @JumpMaster's limiting to 70A. So also all negative currents are shown as 70A... ;( @palachzzz- it's just a small change. I've already done this once to @JumpMaster's version: https://github.com/chriull/WheelLogAndroid/commit/7050910d7cd1509cb8d90b5702eb2d45e59399d4?diff=unified
  21. Just found a nice summary on http://batteryuniversity.com/learn/article/how_to_charge_when_to_charge_table (reduced to li-ion): " Keep a battery at a moderate temperature. As food stays fresher when refrigerated, so also does cool temperature protect the battery by reducing internal corrosion, also known as parasitic reactions on the electrolyte and electrodes. Avoid deep cycling. Each cycle wears the battery down by a small amount and a partial discharge is better than a full discharge. Li-ion is maintenance-free and the battery lasts longest when operating between 30 and 80 percent SoC. Avoid abuse. Like a machine that wears down quicker under strenuous work, so also is a battery stressed by harsh discharges and rapid charges. Use cells that are optimized for the power and energy requirements as per application and increase that pack size to minimize load-related stresses. Avoid ultra-fast charge. Charge Li-ion Energy Cells at less than 1C (below rated Ah); Power Cells are more rugged and can be charged and discharged at a higher rate. Store Li-ion at partial charge in a cool place. The worst combination is high voltage and elevated temperature. Store Li-ion at approximately 50 percent SoC. Frequently asked question Lithium-ion (Li-ion, polymer) How should I prepare a new battery? Apply a topping before use. No priming needed Can I damage a battery with incorrect use? Keep partially charged. Low charge can turn off protection circuit Do I need to apply a full charge? Partial charge better than a full charge Can I disrupt the charge cycle? Partial charge causes no harm Should I use up all battery energy before charging? Deep discharge wears the battery down Do I have to worry about “memory”? No memory How do I calibrate a “smart” battery? Apply discharge/charge when the fuel gauge gets inaccurate. Repeat every 1–3 months Can I charge with the device on? Parasitic load can alter full-charge detection and overcharge battery or cause mini-cycles Do I remove the battery when full? Not necessary; charger turns off How do I store my battery? Store in cool place partially charged Does battery heat up on charge? Must stay cool or slightly warm How do I charge when cold? Do not charge below freezing Can I charge at hot temperatures? Do not charge above 50°C (122°F) What should I know about chargers? Battery must stay cool; no trickle charge when ready "
  22. My 14-C has died.....what went wrong!?

    For 67,2V Gotways @JumpMaster had 52,9V for 0% and 65,8V for 100% decoded in Wheellog - seems to be what GW ?uses/used? This 0% shown at 52,9V are 3,3V per cell. "Most mobile phones, laptops and other portable devices turn off when the lithium-ion battery reaches 3.00V/cell on discharge. At this point the battery has about 5 percent capacity left. Manufacturers choose this voltage threshold to preserve some energy for housekeeping, as well as to reduce battery stress and allow for some self-discharge if the battery is not immediately recharged. This grace period in empty state can last several months until self-discharge lowers the voltage of Li-ion to about 2.50V/cell, at which point the protection circuit opens and most packs become unserviceable with a regular charger. ( See BU-808a: How to awaken Sleeping Li-ion ) Power tools and medical devices drawing high current tend to push the battery voltage to an early cut-off prematurely. This is especially apparent at cold temperatures and in cells with high internal resistance. These batteries may still have ample capacity left after the cutoff; discharging them with a battery analyzer at a moderate load will often give a residual capacity of 30 percent. ... To prevent triggering premature cutoff at a high load or cold temperature, some device manufacturers may lower the end-of-discharge voltage. Li-ion in a power tool may discharge the battery to 2.70V/cell instead of 3.00C/cell;" (from http://batteryuniversity.com/learn/article/premature_voltage_cut_off ) and "To get accurate readings, the battery needs to rest in the open circuit state for at least four hours;"
  23. Wrist Guards That Won't Break Your Arm

    imho the main aspect for a wrist guard is to keep it from bending it too much under "load". Since by this and also by some of the stiffer models its possible to resist more force this has to be "taken" by the rest of the arm - so imho the next predetermined breaking point should be the shoulder/collarbone ;( ? One way to assist the joints a bit is to train the muscels, the other way is to not catch the fall with the wrist but roll! Unfortionately it's a very basic and intuitive reflex (to put the hands anywhere one should not)... ;( Imho a quite perfect example of how to roll off an unicycle was just posted by @EUC Extreme Maybe @Rehab1has some professional tips on how to best protect ones wrists/arms (beside stopping to ride EUC's )?
  24. My 14-C has died.....what went wrong!?

    In this video (1) he revived lifepo cells and not lion - as @Keith mentioned they have a different chemistry and behaviour as our liion. Also the the videos of recovering solowheels could regard the old ones with lifepo cells? at http://batteryuniversity.com/learn/article/low_voltage_cut_off they state the liion cells (could) have a over discharge protection inside which can be disabled again. But they also warn "Do not boost lithium-based batteries back to life that have dwelled below 1.5V/cell for a week or longer. Copper shunts may have formed inside the cells that can lead to a partial or total electrical short. When recharging, such a cell might become unstable, causing excessive heat or show other anomalies" i would "translate" excessive heat with danger of fire... so whatever you try @fourthewin- don't leave your battery pack unattended! I won't consider this as russian roulette - the percentage the app/wheel shows is not the "real" charge percentage - there should be enough additional "reserves". just if the cell balancing by the bms does not work correctly or the cells are already quite aged, the chance of the weakest cell "dying/getting undervoltage/shutting off" rises the lower one discharges the pack... (2) +1 especially riding a wheel down to 10% and leaving it for one night/day does not inflict any problems! There must have been some other prob already. did not some ks14 measure "wrong" voltages, so the wheels shut of way to early while regenerative braking? - maybe this could also inflict "low" battery state somehow and be "reset", if one knows how... or just some way for their bms to be reset... looking forward to @fourthewin's report on how this will be resolved by Will! (1) this is a "bad" video anyhow - he shows many stupid things and has no idea of what he's doing. (2) @zlymex posted imho once a ?constant current source" to effectively balance the cells - such a thing should make more sense than driving the wheel "more conservatively"
  25. My 14-C has died.....what went wrong!?

    Don't know how it is in the US - here in europe the warranty on the batteries is normally less tha a year...
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