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Chriull last won the day on December 3 2016

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About Chriull

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  1. @WARPed1701D reported a voltage drop directly after charging from 83,9V to 82,5V within ~20 minutes for his V8 (20s2p?) So as a first try for the 20s packs one could set the charge cut off voltage this 1,4V higher (for 16s 1,4V*16/20 ) and look at the reported voltage of the wheel afterwards if some adjustments are needed. With few iterations you will find the "perfect" voltage for your wheel. From readings at BU this voltage settling are dependend on the different cells, their state and the charging current. So if you have a 20s4p configuration maybe +1,4V * 2 / 4 could be a better first try? Ps.: If one wants to really make it right the accuracy of the voltage reported by the wheel should be checked - as for example some ks14 serie was way off...
  2. Ps.: I hid your duplicate of this topic
  3. There was a report sometimes somewhere here of a transparent ?silicon/plastic? covering of the wheels shell
  4. Driving around half of lift cut off speed could give good efficiency = longer range. Did not think through this in detail, but max power is available at this speed, motor efficiency raises with speed (?and drops again somewhere at the end?) and air drag raises with the square of the speed. So the sweetspot should/could be somewhere in that range? Inclines should be taken with as much speed as possible - by going up a steep incline slowly efficiency is terribly low. But this gets one near to overleaning the wheel -> faceplanting So preventing (steeper) inclines should help Keeping steady speeds, slow and seldom accelerations, crouching oneself to reduce airdrag, keep oneself balanced so the wheel has less balancing work,... Also have the wheel calibrated ?to ones riding style/positioning? could help - this came up as reason for low range in one of the discussions. Don't know if this was just a rumour/hypothesis or real practical knowledge? Treat the batteries nicely so they keep up their capacity! No storing of especially a fully charged wheel in hot places! From http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries : "In terms of longevity, the optimal charge voltage is 3.92V/cell. Battery experts believe that this threshold eliminates all voltage-related stresses; going lower may not gain further benefits but induce other symptoms" So just charge the wheel to 3,92*20=78,4V for 84V wheels or 62,7 for 67,2V wheels directly after each ride and fully charge it before you go for a ride. These are "saturation" voltages - one has to charge to a bit higher voltages so the cells settle to this voltage (after 15-30 minutes). If you know beforehand that you don't need the whole range you can also "topcharge" before riding to just 80-90%. This part charging is imho best achieved with a charge doctor (or two - don't know how comfortable it is to change voltages) And every know and then one should give the wheel a full (saturation) charge so the cells keep balanced! Edit: PS: but most important is to have fun riding the wheel! If one overdoes the "treatments" and not rides anymore all the measures are counterproductive!
  5. Faster charging

    No luck needed - they will be dead once the are fully discharged. No need to solder them anymore...
  6. EUC used as Batterie Booster

    You'd need a step down converter which transforms the 63/67,2/84V to 12V with the ability to deliver some hundreds of amperes for some (short) medium burst. Maybe a little less for motorcycles? Presumably this is best solved with some big capacitor banks? Anyhow - to big to just have it in the pocket while riding just in case...
  7. ACM 1600 Anti Slip Pedal Studs

    @Rehab1 "Not sure why there was a double post. Sorry! I attempted to remove it with no result. Moderators: any ideas? Option tab does not show up. " Don't know - i just hid the duplicate for you.
  8. From E+ to P speed

    There are battery expansion sets available at for example 1radwerkstatt.de . I would not recommend some sack, tape, screws and tinkering. You want performing batteries and not junk!?
  9. Bought Charge Doctor. Now What Do I Do?

    There is enough energy available throughout this range. But Less voltage drop until empty would still be better. The have a different chemistry.
  10. Bought Charge Doctor. Now What Do I Do?

    As they are talking in table 3 from 100% charge this 4,2 peak voltage/peak charge voltage is for "saturation" charges (where one does not cut iff at a certain voltage threshold but continue with the normal liion charging with this max voltage). Your cells "recover" from the almost 4,2V quite immedeately - the degratation figures in table three are over one year! As a 100% charge at 25°C does just 4% degratation over a year i would also not worry too much about full charges... Edit: read in the wrong column - degratation is 20%... Does not change much for this specific short time stress, but for "normal" storage....
  11. Rocwheel GT16 92V coming soon (2018)

    Batteries and electronics are already inside the wheel? The metallic sidewalls wozld be perfect heatsinks for the mosfets, short wiring distances and only the charging and some led cables would go outside!
  12. Bought Charge Doctor. Now What Do I Do?

    Voltage after resting would make sense. The voltage while charging or immedeately afterwards depends also on the charging current. % of max capacity is harder to obtaun. Details to this topic: http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries For table 2 for example cut off voltage of the charger is taken along with the capacity. They take the value which makes sense in the context. For battery lifetime prolongation imho the reference mostly to % of the capacity or voltage (after resting). Both of this value are very correlated. Just as already @LanghamP wrote, the shown capacity from the wheel is quite "useless"
  13. 18l presale specs

    A connector between the normal charger and the battery should be enough. (As it is in the wheels - two connectors and two cables). With the "new" interconnection between the two packs (?since the S series?) there seems to be some "syncronisation between them. There is maybe just some special connection/disconnection sequence to be followed so that the packs cannot go up in smoke if one is "offline" due to some cell/bms problems. But this should be shown in the abovementioned "battery swap" video. ... Or much better would be handling this by some BMS logic, so that nothing can happen in whichever sequence and state the packs are reconnected! Btw: are there information available about this new battery pack interconnection?
  14. The controller normaly works on the "error" (difference of actual value to desired value) - so a square function would not work out. The sign has to "survive". (Or the "error" always has to stay positive..) An optimal transfer function can be calculated for a given system - as far as i have read again some articles revealing a bit if my fading memory of past education somehow with laplace transformation and step response... The same can be achieved with a PID controller. Or it could be set up with some trial an error/setup guides and reach (more or less) satisfatcory results... And the developers can reuse readily available and tested source code.
  15. That could be a nice question for "our" firmware guys. Whats the input and output values of the pid controller and which factors for the p, i and d parts work (respectively how to determine sane values). Just looked at http://ctms.engin.umich.edu/CTMS/index.php?example=InvertedPendulum&section=ControlPID it seems that only a P controller should lead to overshoot reaction (wobble). The D part should help to eliminate this. Maybe the I part could "solve" the in the article mentioned "sideward move problem", adjusts gyroscope drift, or whatever? Maybe @esaj got into this with his selfbalancing robot?