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BBSHD weak power, battery voltage swings, ludicrous, need help trouble shooting.

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    BBSHD weak power, battery voltage swings, ludicrous, need help trouble shooting.

    BBSHD was working fine for over 1,000 miles, and then I decided to mess with it....

    Installed ludicrous controller. Installation went smoothly but the test ride wasn’t great, jerky pedal assist power delivery and far less than standard luna controller power using the throttle or pedal assist at all levels.

    The battery voltage indicator on the display showed significant voltage flux/drop while over a very short test ride. 57 volts down to 40 and even 35 under throttle. Battery shows as drained to 37 volts after a ride around the block while pedaling.

    I have a Luna 52v Samsung INR 18650 25r 52v 12.5ah battery with about 50 cycles on it.

    I tried charging the battery using a grin satiator and it charged for a few minutes and then threw a “power fault” error.

    I noted a bad xt60 terminal on the charging cord where the connections had failed due to repeated wire bending. Replaced xt60.

    Battery is charged and voltmeter indicates 52.9 volts.

    Tried "jumpstarting BMS" by setting satiator to lead acid profile and force starting while feeding through the battery output xt90. Satiator charges for a second before indicating charging complete and shutting down.

    Read the programming thread on this site and reprogrammed the new controller.

    I tried riding again and note significantly reduce power and hesitating jerky power delivery continues. Wonder if it could be a phase wire. Double check and all connections appear at the controller, battery and display appear good.

    Switched back to original controller. No change in symptoms or usability. Switched back to ludicrous, ditto.

    Display indicates only drawing 1-2 amps of power. Display fully functional. Indicates 45.6 volts only despite voltmeter indicating 52.9.

    Any troubleshooting suggestion would be greatly appreciated.

    I don't know the C rating of your cells, but if the C rating is 3 then the battery might not be capable of putting out continuous current over 37.5A (12.5 X 3).

    The product description of the battery that you have says "50amp continuous 80amp burst BMS". I wonder if that is for the BMS or the pack? If it is for the pack, then the C rating for your cells must be 4 (50A divided by 4).

    I have found that allowing a margin for safety makes for smoother operation of the components. For example, if your battery is capable of putting out "50amp continuous 80amp burst", limit your current to about 30 or 35A in order to take it easy on your battery. If you draw too much current from your battery, then you may cause one or more bad rows. If that happens, the pack has to be rebuilt.

    So when you switch back to the regular controller, is everything fine or is it wonky?
    Last edited by commuter ebikes; 03-12-2017, 12:08 AM.


      Thanks for your ideas. When I switch back everything is still wonky. Bad symptom persist. Display indicates that only 1-2 amps of power are being drawn. When the bike was working properly, it indicated up to 30amps. If the display is working properly as a measurement tool, I am only getting 2 amps max now. Cells are rated for 25 amps continuous. I believe the BMS was quoted as capable of 50 amp bursts.

      When I followed the procedure for "jumpstarting" BMS by charging through the output connector, I'm not sure it worked properly as the satiator indicated immediately that the battery was full and doesn't appear to have put power through. Do you think it might be BMS not working properly? Any tips for correcting that?


        Does the fact that I measure 52.9 volts of battery output mean that the bms is functioning properly, or could it still be shutting things down when I press the throttle and/or pedal?


        • HarryS
          HarryS commented
          Editing a comment
          The fact that you get 52.9 volts when a fully charged 14S 18650 is 58.6 volt says the battery has an issue. If it's easily opened, walk a voltmeter probe up 15 pin connector on the BMS, checking every two adjacent pins. That gives you the 14 cell group voltages. Mayber all 14 are down, or maybe one/two are bad.

        • commuter ebikes
          commuter ebikes commented
          Editing a comment
          Check for a bad row.

        • nadidlab
          nadidlab commented
          Editing a comment
          Well it seems so obvious, now that you guys say it to me. Thanks! I should have recalled that my charger is set to 57.6 volts so 52.9 clearly isn't correct-Duh!

        Originally posted by nadidlab View Post
        Does the fact that I measure 52.9 volts of battery output mean that the bms is functioning properly, or could it still be shutting things down when I press the throttle and/or pedal?
        I don't know the answer, but I do know that on my ebikes it works as follows:
        (1) BMS shuts down the voltage if I draw too much current. At this point, I have no power.
        (2) I power cycle the system by unplugging and plugging back in my battery. This resets the BMS.
        (3) At that point, I am good as long as I don't draw too much current again.

        If you get too frustrated, contact this local electronics tech at The guy is an absolutely brilliant troubleshooter. He wired up all four of my bikes. His work is reliable beyond belief.
        Last edited by commuter ebikes; 03-13-2017, 06:41 PM.


        • nadidlab
          nadidlab commented
          Editing a comment
          Very helpful local link. Thanks so much!