No announcement yet.

Anyone ever seen this behavior?

  • Filter
  • Time
  • Show
Clear All
new posts

    Could it be a battery BMS problem? How would someone check that?

    It sounds like more a defective battery issue.
    Last edited by Jon; 09-13-2016, 09:20 AM.


      Bafang has a video about how to do it but my model looks a lot different than the one in the video. I was able to remove one side of the case but could not access the rest because it was all hot-glued together (quite a bit of hot glue actually). I'm trying not to worry about it too much for now. Lunacycle was kind enough to send a new motor and I will hook it up with proper connectors once they arrive and see what happens.


        The new motor arrived today. As well did the XT90-S connectors.
        I spent the majority of the day soldering on the new connectors and swapping out my motor and wiring harness etc..

        Threw the battery on the bike, turned it on, and ... ... ... ... no change.

        Still has the issue of voltage drop and no power to motor. I suppose all signs lead to the battery at this point??

        I always had my suspicions about it anyway.


          Your voltage stab test already proved the problem was upstream from the motor. New connectors. Now you know it's the battery.


            I'm even more confused now.
            Yesterday out of frustration I threw the battery back on for more troubleshooting and out of nowhere it decided to behave as normal. Showing about 50v on the display so I decided to go for a ride. Got about 6 miles out and then out of nowhere the voltage drops and I have no power again. Suddenly I'm supplying all the power. No amount of wiggling cables and connectors seems to have any effect. I remove the battery and then put it back. Turn on/off the display a few times and suddenly it starts to work again. No rhyme or reason as far as I can tell.

            Sometimes the display flashes an icon that looks like an exclamation mark inside of parantheses.((!)) WHAT IS THIS?

            When the display reads low voltage the battery test button (on the actual battery) also reads as dead. Suddenly when it decides to work again the battery test button reads as normal.

            Yesterday when charging the battery it got pretty hot along the top (above the BMS I believe) and coincidentally in the same area as the warped plastic. Today when I charged it it barely even got warm.


              Sounds like battery needs to be replaced.


                You almost certainly have bad connect(s) on the batteries. This isn't something to fix unless you are really capable as there is so high current to deal with. If the pack is still under warranty, I for sure would send it in and let the dealer replace it.


                  i experienced the same exact thing, you can try different battery pack. or for the meantime mount your battery inside your backpack.


                    Originally posted by pcliteuser View Post
                    i experienced the same exact thing, you can try different battery pack. or for the meantime mount your battery inside your backpack.
                    Maybe I'm confused... How would changing the location of a bad battery, make it any less bad?


                    • pcliteuser
                      pcliteuser commented
                      Editing a comment
                      on my experience, the vibration from the frame messed up my battery pretty bad (motor starts to jerk then shuts down, destroyed the battery holder inside the pack, shorted some wiring, then after few weeks battery shuts dows when it reaches 50%). i ride offroad 90% of the time.

                    • marjamar
                      marjamar commented
                      Editing a comment
                      What battery was that? If a bike battery cannot be mounted to a bike without breaking something inside, it is built wrong.

                    If the battery is getting hot, stop charging it for now, you could possibly by-pass the BMS, but that would require a bit of "surgery" that might not be a good idea.

                    If you're used to charging Lithium packs with something like a R/C charger for LiPo, it might have a setting for Li-Ion, but then you still need a way to prevent draining it too low.

                    Best probably to just get it warrantied if you can, sorry to hear it wasn't a simple solution. : (


                      It's within it's 30 day warranty window still so I won't be doing any surgery (thank goodness).
                      The guys at Lunacycle have been pretty helpful and cooperative so far but are a little puzzled as to the cause of the problem. Also, the time it takes for a return to go through all the channels over there is not exactly what I would call speedy and in the time it has taken to put it all together they have sold out of my battery and are unable to offer me a replacement until they get another shipment. They are backordered from China so they have no idea when more will arrive.