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    Jerky Motor Behavior (BBSHD)

    i need help i'm experiencing jerkyness on my motor today, its like the motor goes on-off but lcd stays on. I'm always on pedal assist 0 I only throttle & pedal. problem started when i first press the throttle few seconds after turning on the bike and doing couple of pedals.

    troubleshooting:
    1. check for error (no error or red icon on the lcd)
    2. check for battery level (i'm using bottle battery 52v 11ah - the current shows 49-50v when moving so my personal experience i'm guessing 50-60ish % of power i still have) - i also tried draining the battery before it is also jerky but not much power not much kick unlike what i experience today. and when i press the battery indicator button it gives me 2 bars.
    2. check cable contact (motor to harness - reseated, throttle to harness - reseated, LCD to harness - reseated) i dont use brake inhibitors
    3. check for motor temp (normal to me not even warm yet - i always touch motor after every ride so i know whats hot & whats warm)
    4. tried lifting the rear wheel then 10%, 50%, 100% throttle on all gears (good result no jerkyness just the way i want it)
    5. tried riding outside (jerkyness is back - this time when i do full throttle the motor & lcd goes completely off - full throttle on biggest cassette = motor jerks after 3 secs, full throttle 5th gear = 3 secs, full throttle on smallest cassette = it only took roughly 1.5 secs)

    motor changed its behavior (after doing troubleshooting)
    when the motor starts to jerk, my pedal assist 0 for some reason is like pedal assist 1


    what do you guys think is the problem?
    Last edited by pcliteuser; 07-24-2016, 08:22 AM.

    #2
    My money's on a loose connection in the controller, bent pin in connector, or a failing throttle.

    unplug/replug all plugs in controller, check straightness of pins, and plug in speed sensor and try using it in PAS mode. (if speed sensor is already plugged in try unplugging it and going throttle only that way. )


    Really if there's any plugs you're not using that are capped off, might want to check them as well, I would assume that if there's some water in the cap it might cause an intermittent issue.
    Last edited by paxtana; 07-24-2016, 09:27 AM.

    Comment


      #3
      it happens that my battery is not charging as well so i'm not sure if its a motor problem, when during my 1st post my battery is @50ish percent so i had to remove that whole kit and convert the mtb back to stock setup :(

      luna guys helped me but issue is not resolve yet, they are sending me cable xt60 barrel adapter, so for the mean time i'm charging the battery on awkward way "not sure if there's bad effect on the battery charging it this way"

      Click image for larger version

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      once i fix the battery charging ill check if the jerkyness of the motor is still there :(
      Attached Files

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      • pcliteuser
        pcliteuser commented
        Editing a comment
        i thought this method recharges my battery but instead it drained the battery :(

      • paxtana
        paxtana commented
        Editing a comment
        Are you sure you had it connected to the correct contacts and it was not shorting it out

      • pcliteuser
        pcliteuser commented
        Editing a comment
        no short, no spark and the charger whirls to life when i connected the cable. i guess i'll have to wait for the cable to arrive then "i hope that will fix the problem"

      #4
      tried riding outside (jerkyness is back - this time when i do full throttle the motor & lcd goes completely off - full throttle on biggest cassette = motor jerks after 3 secs, full throttle 5th gear = 3 secs, full throttle on smallest cassette = it only took roughly 1.5 secs)
      The fact that there is a delay before it starts cutting out, and that delay is shorter in higher gear (higher current draw) tells me that this is a current delivery issue. Weak battery, probably, which can't keep up for long. Low charge or imbalance could do that. Or bad cells, but don't jump to that conclusion.

      Or, maybe, a high resistance connection someplace in the motor power wiring.
      Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

      Comment


      • Sebz
        Sebz commented
        Editing a comment
        I agree with JP, you are at 49V....full throttle on small gear is a high current demand the voltage sag will be a few volts enough for hitting the cutoff! Recharge it to 80% or 100% once you get the adaptor and test again... I'm not so sure that the discharge port on a BMS can accept a charge.....I know it resets the BMS in case of trouble but charging? not 100% sure on that one

        BTW 49V is about 15-16% left and 50V about 27-30% and 51.8V is 50%

      #5
      the replacement xt60 barrel adapter works the battery is now charging, but looks like something is wrong with my battery i need to flip it upside down (bottle battery 52v 11ah) and wrap it with 2 industrial velcros for it to run stable.

      Comment


        #6
        Originally posted by pcliteuser View Post
        the replacement xt60 barrel adapter works the battery is now charging, but looks like something is wrong with my battery i need to flip it upside down (bottle battery 52v 11ah) and wrap it with 2 industrial velcros for it to run stable.
        That sounds like you still have connection issues someplace, then.
        Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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          #7
          I think i just fixed my problem it's been a week now and i don't have any issues on my bike :) so here is what i learnt

          the jerkyness of the motors was caused by the battery condition all along. - the "battery not charging" part is different problem though and it was fixed by xt60 barrel replacement.

          Bottle Battery was damaged inside because of off road abuse
          Click image for larger version

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          because of this the top part where the BMS is located some part got loose causing it to trip itself here is the video: https://1drv.ms/v/s!AkfKtrEULtPWsDvfjUaFf4MGptMW


          noob troubleshooting:

          Step 1: i picked up pieces of hardened glue inside the battery and jam it on top of bms to create pressure then electric tape it
          Step 2: jumpstart the battery just to freshen it up (jumpstart for 20-30 seconds)

          works for me :) - motor runs smooth again like new, but my long term setup is to mount the battery inside backpack to avoid vibration.

          Comment


            #8
            Yay!

            It's really hard to diagnose when 2 thing are going on at once, and intermittent problems make it downright diabolical. Good job.
            Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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