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    Battery Life - difference between module and display

    Reaching out to see if anyone can shed some light on this.

    I have the bbshd with the color bafang display DCP-18.
    Having called in before and done some voltage testing, everything was fine. When riding recently, the display will show me 47v on the 48v battery back. It will randomly shut off and or just die. Checking the battery itself, pushing the button shows it's 3/4 full.

    Works fine if the unit is fully charge, just when I get into the high 40's in voltage, am I getting this weird cut out problem .

    any thoughts?

    #2
    checking back to see if anyone from Luna or outside might have an idea of why the battery module shows 3/4 full, but the display is showing me 45-47 volts, which is below 50% or more.

    Comment


      #3
      Hi mkyb14,

      I would recommend taking an actual voltage reading of the output of the battery. with a reliable and accurate multi-meter. To see who is telling the truth. :-) SOC or State Of Charge indicators (both display and battery) as well as voltage indicators have been known to be inaccurate. Verify when the actual meter proven voltage cut-out point is reached.

      Your controller has a programmable LVC setting (Low Voltage Cut-out) which I would believe to be 42-43 volts. Have you changed this? Do you have programming capabilities? You battery BMS will also shut down the battery output if voltage gets too low. But this is generally a much lower setting ( ~37-39 volts), and your display would shut off.

      A chart for 48 volt nominal Li-Ion SOC for reference...







      Regards,
      T.C.


      See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

      Comment


      • mkyb14
        mkyb14 commented
        Editing a comment
        so I have not done any programming. The kit as it came from Luna Cycle is not tampered with. I only changed the settings on the dpc-18 display to match the bike and be in imperial / volts. I have checked the battery terminals with a volt meter and it does register when fully charged the 54.6V. I unplugged the shift sensor and that seems to have cleared up most of the stuttering / shut off that was occuring. I haven't ridden much due to the holidays etc.

        I'm next going to check my cabling and shift sensor to see if those are some how defective and creating the issue.

        I took the bike out yesterday to pick up my kid from school, battery buttons always show it's full, DPC-18 showed 50.0V, got to his school a couple blocks away and the entire bike shut off. 50V should be no where near the cut off if people are stating that 43ish is the default one programmed by Luna in the kit. I fully recharged it over night and will rip around the neighborhood to test this again, since lugging a Yuba Mundo lux with a kid on the back was brutal uphill at a 6% grade.

      #4
      BI have a similar issue with a × Bafang BBS02 750w Mid Drive with Upgraded 3077 Controller

      My display shows a complete battery discharge. I mean 00000. The battery is fully charged and the motor runs for about 1 minute then the display goes to 0000 charge and then shuts off. I turn the display back on and it then shuts off. Eventually the display will not turn on at all. Battery checks out OK. I’m thinking it is the controller. But the controller is built in to the motor. I have changed the display, but same issue. Any ideas other than a new motto?
      Fast forward 1 week.
      Problem solved
      Battery connection got hot and melted some plastic causing a short. Cut away the meted plastic and shined up the female connector.
      Last edited by syancey; 10-19-2019, 09:45 AM. Reason: Solved

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