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So I'm pretty sure my entire motor and battery are toast.

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    So I'm pretty sure my entire motor and battery are toast.

    Just upgraded to the Golden Pie V5 rear hub motor kit, and just got it together and started riding it today. All was well until I hit a small pothole in a road, and the motor seized up and made a loud humming noise while turned on. It seemed that it wanted to turn backwards. I ended up pushing it home and got it in the garage to check it out. I had left the display at home because I hadn't mounted it yet. Plugged it in hoping to get an error code so I could at least find out whats wrong, but the battery lasted about 5 seconds. At this point I realized the motor was seriously draining my battery - when I'm usually about 40%-50% capacity is now empty. To make things worse, the battery now wont even charge. I honestly want to love ebikes but after having problems with 2 motors in a row (and now a bricked battery) I just don't think I can bring myself to buy another.

    My initial guess... and it is very initial is that during the bump one of the hall effect sensors in the motor shifted position or was damaged. The hall effect sensors tell the controller which position the motor is in so the controller can send the correct waveform on the phase wires to spin the motor forward.

    If a hall sensor shifts, the motor and the control can't properly figure out which position the motor is in. The result can be a loud hum or vibration in the motor as the motor turn rapidly on and off. Imagine the typical sobority test of standing on one foot while touching your finger to your nose. If you are drunk enough to disruption the signal between you brain and your arm, you just randomly poking somewhere near your face until you fall over :(

    The significant drain in battery could be because the the controller was send full power to the motor while it was humming.

    Luckily, the inability to charge the battery is probably a good thing. Because of the high current flow the BMS probably shut off the battery to protect it from overload. You and reset it using the instructions at.

    EDIT: EaTCarbs mentioned the he noticed the problem after hitting a pothole. A mechanical shock can cause a loose connector to become undone or a sensor to shift. I considered the hall effect sensor first because 1. It is a physical component which can shift and 2. a faulty hall sensor can cause the motor to rapidly turn on and off.

    A second troubleshooting consideration is the the fact that the motor stopped working soon after installing it. The sensor is attached with a small amount of adhesive. It would be pretty common for the sensor to be attached well enough to pass factor testing but detach after a sharp impact.
    Last edited by funwithbikes; 04-28-2017, 09:41 PM.


      Thanks for the quick reply. My battery isn't the shark pack but I'll try translating that to my own. Another interesting thing with the wheel is that it meets heavy resistance when trying to spin in either direction (while unpowered).


        Yes, the reset procedure is very similar with most standard BMSs.

        Interesting heavy resistance while unpowered is a valuable clue. That probably means that there is a mechanical issue in the hub. I would start by considering three things: 1 The bearings. 2 The clearance between the the rotor and stator and 3. Freewheel.

        Resistance implies that something is preventing normal rotation. How heavy is the resistance? Can you barely turn the wheel? Does it turn but stop immediately? Does it continue to rotate for a few seconds after spinning it by hand. Does the resistance change depending on the position of the motor? Can you hear a noise as the wheel rotates? Can you feel anything if you hold one hand on the axle as your rotate the wheel? Do the noises and vibrations change depending on which direction the motor is rotating.

        If none of this makes sense just upload a video. Nothing perks the interest of a community like a good trouble shooting video :)

        My money is still on a hall sensor which came loose and is now wedged between the rotor and stator.


          Trying to make sure I understand this correctly. To jump start with a charger with a barrel connector like the picture shows, I would connect the two wires that I would normally have running to the motor, correct?


          • funwithbikes
            funwithbikes commented
            Editing a comment
            I am waiting for my luna charger and battery to arrive. Someone else will have to help with the specifics:(

            The basic idea is that a ebike battery pack (with a bms) has two connectors; 1. A discharge port which normally goes from the battery to the motor and 2. A charge port which normally goes from the battery to the charger. When the bms shuts off it won't let any current flow into the charge port or out of the discharge port. The prevents overcharging or over discharging under normal circumstances.

            To reset the bms you want to apply a charge voltage to the discharge connector of the battery. While this is a pain in the butt... It means that you have disconnected both the charge and discharge connectors to make sure the the original fault has been removed. Applying the voltage turns the BMS back on.

          These damn hub motors using internal controllers make it hard to disconnect the motor and eliminate the lockup situation you’re faced with.

          I understand your frustration and perhaps eBikes aren’t for you? But if you can survive the steep learning curve and get things to settle down, you’re in for a real treat.

          The basic thing for resetting pack BMS is to attempt to feed a charge through the connection that runs to the motor. That requires some careful rework of connectors and some basic understanding to avoid shorting things. Although the power out side of BMS can usually provide enough current fry most alligator clips along with your nerves….


            Originally posted by EaTCarbS View Post
            Thanks for the quick reply. My battery isn't the shark pack but I'll try translating that to my own. Another interesting thing with the wheel is that it meets heavy resistance when trying to spin in either direction (while unpowered).
            This cogging can also be an effect of contact between the phase wires.

            I also prefer an external controller. It makes troubleshooting a lot easier if you are willing to remove and replace.

            I sympathize with the OP with his frustration with a lack of reliability in his exposure to ebikes. This happened to me. I persisted, admittedly throwing a lot of money and effort at the problem, and I quickly broke through my few problems. I have a lot of fun now riding around.


              Attempted to reset my battery using the method shown with the barrel plug. It gave a spark and a loud pop at first and I instinctively pulled it away. On the second try, the fan on the charger spun for a fraction of a second, but nothing. Any further attempts did nothing, and the battery still isn't charging. I'm guessing the BMS is toast?


                Did you but this kit from Luna? If you did you really need to be on with Luna support, also you seem to have 2 separate issues to repair, first disconnect battery from controller, check controller wires carefully where they exit motor for damage as it could be shorted phase wires here or inside motor. Contact Luna or supplier support regarding battery. while we are well intentioned amateur helpers you have a serious problem.

                Barrel connectors can easily be shorted by plugging them in hastily, in my opinion they should nor be used at all for batteries.


                  Decided to bump this post since I've started working on the battery. Turns out one of the solders was bad and somehow came loose during this incident, I've just re-soldered it and the battery seems to be charging now. I'll update the battery status after what I presume will be a good charge. I've tinkered with the motor a bit but its not an easy thing to take apart.