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Chriull

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Everything posted by Chriull

  1. Great that nothing grave happend! Not really anything to be seen... You have a bad bluetooth connection - there are many disconnects of 10-20 seconds in your log. So maybe also just while your accident
  2. I meant this stuff that was on your board before, fixing every connector and some other parts. Edit: Photo: Here you see the hall sensor connector (just above the big green capacitor) at my previous KS16B/C board with the white stuff fixing it. I am not sure if this is really necessary, but there are quite some vibrations/shocks happening with the EUC...The other connectors for LED's, speaker etc are not fixed with this stuff, and they never got loose... And another idea/question: afaik ks wheels show hall sensor faults with the led rings. If i remember right it was the first and last led of each stripe lighting in red. Did you notice such a pattern when you had these incidents happening?
  3. It's feasable, but personally i would not recommend it. You'd need to make 100+ mechanicly and electricly reliable connections for ~ up to 10A continous and higher peak currents without damaging the cells thermicly. Cell matching seems to be the primary influence for good performing and long living battery packs. The weakest cell is the one which determines your packs capablities, and it'll be the one taking the most stress and deterioate as first... If you decide to build your own pack, this articel seems serious to begin with: https://www.electricbike.com/introduction-battery-design-2/
  4. There are different kinds - with solid and fluid electrolytes. But both electrolytes can cook and vaporize, causing the bulging and explosion/overpressure valve opening. There is even an own wikipedia article about bad quality electrolyte capacitors on the market about ~10-20 years ago: https://en.m.wikipedia.org/wiki/Capacitor_plague. If the quality is ok and they are used within their specification they should reach lifespans around and longer than 5 years (was mentioned in this or some similar articles...) +1. My guess would be that the mb just doesn't work anymore, because the blown capacitor(s) is/are missing...
  5. Yes - that's the part where the wheel reports the exactly constant speed. So some problem for the wheel getting the right speed data which leads to the hall sensors... He did not report of any correlation with bumps, but such a thing can easily be overseen if one concentrates on trying to stay on the wheel once it behaves such weird. Besides the connectors of the hall sensor wires one should inspect the axle, where the cables come out of the motor, too. There the insulations of the wires like to ?fray/wear through?. Maybe they short just by acceleration/deceleration change? @Augus after swapping your motherboard you fixed the connectors again with something like this "white gluey stuff"? @AugusThat's s something you should try once you opened your wheel for inspection!
  6. According to todays "state of the art". 1C is about the "border", and a bit less recommended. Most manufacturers today specify 0.5C or even a bit less. But maybe we could hope for serious improvement to come: "One assumes that all charge energy goes into the battery, whether charged slowly, rapidly or by ultra-fast method. Batteries are nonlinear devices and most chemistry accepts a fast charge from empty up to about 50% state-of-charge (SoC) with little losses. NiCd does best and suffers the least amount of strain. Stresses occur in the second half of the charge cycle towards top charge when acceptance of lithium ions in the anode of Li-ion becomes labored. An analogy is irate drivers fighting for the last parking spot in a shopping mall to catch a sale special.Applying an ultra-fast charge when the battery is empty and then tapering off the current when reaching 50% SoC and higher is called step charging. The laptop industry has been applying step charging for many years. The charge currents must harmonize with the battery type as different battery systems have dissimilar requirements in charge acceptance. Battery manufacturers do not publish charge rates as a function of SoC. Much of this is proprietary information.Research companies claim to achieve benefits with pulse-charging Li-ion instead applying the regular CCCV charge as described in BU-409: Charging Lithium-ion. The scientific community is skeptical to alternative charging and takes the “wait-and-see” approach." from https://batteryuniversity.com/learn/article/ultra_fast_chargers
  7. You're welcome! The almost overlean was before the incident. Just this "oscillation" was afterwards at the end of the log. Just out of curiosity i would be interested how you experienced this situation - how it started/?how you started this? And how it felt like.
  8. The importance of balancing seems to be "discussionworty" - at least as the articles at batteryuniversity.com express it. Much more important seems the cell matching - this seems to be the number one factor. But cell balancing could /should be able to at least delay the end of a battery pack. Balance voltage threshold is normaly specced at 4.2V for the BMS i've seen. Balancing could start at any other (lower) voltage, but would not make much sense to bypass by this all cells in the end as the they are charged to 4.2V.
  9. Beside direct board damaging they loose their capacity and increase their resistance already before bursting. And since they would be needed could lead to any weird behaviour/faults....
  10. Do you have any sources for charge cycle vs. charging current? Especially in the range like here between 0.1C and 0.5C? I've found nothing regarding this on batteryuniversity.com - imho a great collection of li ion cell knowledge. Just: "Apply the ultra-fast charge only when necessary. A well-designed ultra-fast charger should have charge-time selection to give the user the option to choose the least stressful charge for the time allotted. Figure 2 compares the cycle life of a typical lithium-ion battery when charged and discharged at 1C, 2C and 3C rates. The longevity can further be prolonged by charging and discharging below 1C; 0.8C is the recommended rate." at https://batteryuniversity.com/learn/article/ultra_fast_chargers "The advised charge rate of an Energy Cell is between 0.5C and 1C; the complete charge time is about 2–3 hours. Manufacturers of these cells recommend charging at 0.8C or less to prolong battery life; however, most Power Cells can take a higher charge C-rate with little stress. Charge efficiency is about 99 percent and the cell remains cool during charge." at https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries So, at least there is nothing mentioned of any advantages or disadvantages within the 0.1-0.5C range... Also part time the time per day at full charge in regard to cell degradation. There is "just" the number that at 4.2V and 25°C there is a 20% capacity loss after a year. I'd strongly assume that 12h every day over a year will lead to 10% capacity loss. Although it's speculation to conclude from a continous state to some "part time" state? That's undiscussable imo one of the main points. Fortionately with the battery packs capacity growing and by this more cells in parallel the situation got better. But still the 4p cells will still be burdened with their max 10A continous discharge current. And maybe a bit above. So @MBIKER_SURFER "idea" to changing to some 1500Wh EUC will not only give him more capacity to drive his needed distance every day, but by the less burdened cells longer lifetime. ... And this 10 Amp max continours current specified for many of the used li ions in EUCs are still 2-3C discharge for them: Figure 4 demonstrates capacity loss caused by the structural degradation of an older Li-ion when cycled at a 1C, 2C and 3C. The elevated capacity loss at higher C-rates may be lithium plating at the anode caused by rapid charging. [See BU-401a: Fast and Ultra-fast chargers] Figure 4: Cycle performance of Li-ion with 1C, 2C and 3C charge and discharge. Moderate charge and discharge currents reduce structural degradation. This applies to most battery chemistries." from https://batteryuniversity.com/index.php/learn/article/bu_808b_what_causes_li_ion_to_die And additional to this "overburden" - this ~10A for a battery cell is the average current, the EUC takes much higher currents "chopped by the PWM signal". I never have seen any articles about peak burdens for Li ions...
  11. Great - so there should be no connection between your incidents and the batteries - but maybe he is able to find the problem and help you out! Your picture already looked a bit strange - now with the wheellog data it seems obviously some system fault: Your logged (from the KS16S reported) speed stays absolutely constant at 25,62 km/h between 13:24:36,55 and 13:24:48,39. All other values (current, temp, voltage, distance,...) were transmitted normally in this time! Here once again a bit more zoomed: You were driving at around 16-17 km/h got a bit slower ~15 and then the log shows an acceleration from ~15 km/ to this "fixed" 25,62 km/h within 1,22 seconds. Quite "nice" but realistic acceleration of 2,3 m/s² - did you/the wheel accelerate or is this just shown here? Inbetween the maximum acceleration is about 5m/s².... quite high?!! After that there is some regenerative braking (negative current, voltage going up) and in the end a big current peak with a voltage sag shown - the end of your "incident". All at "impossible" constant speed reported.... This ("no" speed shown) and the motor rattling (ratched noise) shows the EUC controll out of bounds? Maybe the hall sensor signal missing/disturbed? But strangely only while stronger braking/accelerating? And just sometimes? Maybe really a bad/loose contact? Or just some "weird" defect at the motherboard? Some chip going crazy? Imho nothing to be solved by you/us. With much good fortune you maybe find at your visual inspection some not really fixed connector/"strange" signs at the motherboard/ broken insulations at the cables? At the end of your log there is another strange situation?: There are big speed/current/voltage spikes with about 7 Herz. Much to fast for some willingly acceleration/braking manouver? Is this some "special" trick of you, did the wheel "oscillate" or was this one "ratched noise" event too? And FYI - you had about(almost) an overlean while your ride: While you seem to ride normally in a "sane/and safe" region there once this red dots coming near the blue limit line and (?almost?) touching it, before you stopped accelerating and "really" overleaning. This (?almost?) touching the limit line was before tilt-back speed (note - the numbers for speed in the above diagram are not really km/h...) Here the "normal" graph of this near limit incident: Did you already notice something or was it just good luck/gut feeling that you stopped accelerating? ps.: this "limit values" come from my KS16S, and the values for lift-cut-off speed, "failure" factors for reported current,voltage can differ between our "same" wheels and the distance to the limit with yours a bit farther...
  12. Should be. But with Li Ion's that's "just" the C(onstant)C(urrent) phase which charges the cell to ~85%. Charging the cells with C(onstanst)V(oltage) up to 100% takes longer. Just seen here at https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries were a 1C charge is shown that after 1 hour CC there are ~2,5hours of CV. So maybe my assumptions for charging time in my above post have too be adopted a bit to longer times... Or its just the last percentages (and balancing) happening and not really necessary for each charging? If @MBIKER_SURFER uses by now a 1.5A Charger that should be ~1.5A/12.8Ah = 0.11C charge. So the CC phase should take about 9 hours (from real 0% capacity). So depending on the start capacity the cells should be in average not at a too high voltage, but some 5A charge would reduce this times drasticly.
  13. Be sure that the battery is not at 100% while this not driving days. You could think of a "fast" charger - with 0.5C the battery should be charged within 3-4 hours. If you precharge to ~50% after the ride (and some "break" time for the batteries) some 2-3 hours in the morning should be enough for 100%. The V10F has two battery packs 20s2p with 3200mAh cells? If so 0.5C would be 6.4A - a bit too much for plugs/wiring. 5A chargers are available and mostly plugs can take this. And some cells have the manufacturer recommendation to charge with a bit less than 0.5C. Ewheels state 2h to 80% with their 5A charger. So this precharging in the evening and charging the rest in the morning could work out to reduce "drasticly" the time with full charge for the cells. ... If you have enough time in the morning :(.... Keep an eye on the voltage after full charge. If its steadily dropping this could be a first sign of bad/aged/misbalanced cells...
  14. There are three things that come to my mind: - "magnetic slip" if one brakes or decelerates too hard, the motor slips one "position", gets caught again, slups, and so on. Can sound like ratchet. But i'd say the motors are too strong as such things could happen? - somethings mechanicly "a bit" loose inside the motor and rattoes under high burden. One of the permanent magnets not really fixed? - some current limiting of the mainboard which kicks in and releases fast enough to make this rattling sound. Was afaik sometimes reported with earlier GWs doing fast accelerations at low speeds? Could maybe also hapoen while braking if there is some regerenerative current limit? Speed and current drops to zero - no voltage shown?! You have the csv log file? You know the specs of the BMS used? But as you wrote that the wheel did not shut off, it should be no BMS cut off? Maybe, if its some weird BMS behaviour it only shuts off very shortly and comes back quite imedeately? So the mainboard could overcome the shutoff times with its capacitors, but this weird situation leads to stopped balancing? .... Is some very wild and weird soeculation.... Hard to analyze - there are too many unknowns... I would rule out loose contacts, as your incidents just happen while high burdens (acceleration,braking) and everything works fine otherwise? The company replacing the battery is experienced with EUC requirements? Normal EBike BMS can be a bad choice for EUCs. You asked them already about your problems. Did the problems start with the new battery? The battery charges to the max voltage(~67.2V) Log files from these incidents could maybe reveal something? Did you already make a visual inspection of the internals ?
  15. That is the build in tilt back. For KS wheels it cannot be turned off. Seems with the app it's now set at a too low speed? Yes, it has a strange name in the app. But i can't remember by now and have my wheel not nearby to connect and look for the wording.
  16. The logic is in the PSU. They have this max current limit for the CC phase and a max voltage for the CV phase. And the "low current" threshold to cut off at the end of the CV phase. The BMS just has for each cell an overvoltage protection, that can cut the charge input.
  17. Chriull

    Downhill Issue

    Welcome! Most probably you start with a full battery? Going downhill does regenerative braking and by this gives you an overvoktage warning till the wheel cuts off..
  18. That's great, but limits for EUCs are not really intinuitive - and learning by faceplanting is no fun There is no speed limit to be safe. Maximum available torque decreases with speed. Which means - the less ones accelerates, the higher speeds can be safe, the more one accelerates the lower speeds are safe. Inclines are equal to accelerations, potholes/cracks/bumps need reserves - if one hits them they need additional "acceleration". Even "safe" kingsong wheels with their speed limits can be overleaned without alarms or tiltback if one accelerates/burdens the wheel enough: Not for certain. A bluetooth connection is not 100% secure - if it disconnects you wont get any alarms again. And a fixed tilt back speed gives no security, too if one burdens the wheel enough As in the above link mentioned there exists no overlean warning till now with the EUCs (although the implementation would be quite easy) - wheel manufacturers do not even manage to implement "dynamic" tiltbacks. Tiltacks can be very dangerous by hitting them while accelerating too much as they throw one off the wheel by this "kick back of death". But even this even more easy adoption is not regarded by the manufacturer. So - high speed low to non acceleration! And reserves for overseen potholes!
  19. Unfortionately not As @Mono stated and in https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries is written that a li ion battery stored for a year at 100% has only 80% capacity left. So his question, how your charging routine is. So if one charges after every ride and the battery has by this in average mostly 100% charge something around a 20% capacity drop after a year is "normal". If one charges just before a ride and inbetween the battery sits with something around 30-60% the capacity drop by this will be much lower to neglectable. Also the stated 3-500 charge cycles from the cell manufacturers are valid for ~0.2C discharg currents. With EUCs the burden should be mostly higher. This was until now just the effects tor single cells. In the used packs are many cells in serie which "increased capacity loss problems/occurances". For one the chance to get a not so good cell rises, and on the other side the weakest cell in a pack gets the most stress and by this degrades even faster. A one time voltage measurement is unfortionately not too meaningful. Normal measurement devices are too inaccurate - one needs normally some values over time to compare and see a trent. ...and hope that ones multimeter did not drift too much over time ... Edit: ...and additionaly your charger could get misadjusted over time to just deliver less maximum voltage and so less charge into your batteries.
  20. In the "old" versions on came to the settings by swiping from the left border to the right. Don't know if anything changed inbetween? A bit more natural/android style would be implementing the three dots in the upper right corner...
  21. If there is plenty of power available, there is nothing against multithreading if one wants. The measurement, calculation and control loop is a sequentiel procedure by definition. One can "easier" guarantee time constraints. And there should not be any race conditions possible to stop this main duty. But this could be nicely done with freeRTOS by starting this main task with "highest" priority in at defined time intervalls, and do all the fancy light, sound, whatever stuff with low priority/just once the main task sleeps... ... If one trusts the scheduler, but imho freeRTOS should be reliable? Imho their unique feature are the two motor pwm timers with dead time generation and emergency stop. Another nice hardware feature in other modells are build in comperators, which could be used to generate an interupt in case of too high motor current. Don't know how this is realized by now on the boards - presumably just with looking at the current values in the "normal" control loop. Which is "slow" polling instead of a "fast" interrupt from the comperator?
  22. 10°C could be already a reason? But i never really looked at the range - and i try to avoid driving at such temperatures 😎 Theoretically everything should be fine with such a number, but it's no security. One can get bad batteries with low charge count too.
  23. @MBIKER_SURFER as written wind and cold weather can be a eeason, also different riding style (going faster, more accelerations) Charger could gave started to deliver less voltage - don't look at the charge percent but the voltage reported! The voltage range for 100% charge shown is huge and a big capacity difference. If it's the battery i collected some thoughts here:
  24. Charging liion needs a constant current first and then a constant voltage: https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
  25. Welcome! Please regard the forum rules and write in english, or post in the "local group meetups" subforum within the italian subtopics.
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