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BBSHD with Luna 860c will not turn on.

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    BBSHD with Luna 860c will not turn on.

    Hello All,

    I'm looking for some insight into what may be causing a problem (it will not turn on) with my power assist.
    • Bafang BBSHD - Program Hot Rod
    • 52v Triangle Samsung INR 18650 25r 52v 12.5ah High Power Battery
    • Luna 860c Display
    • 52v 3amp Luna Mini Charger
    This unit has been installed and used regularly on a handcycle for about two years, working pretty much problem free. I'm a fair weather rider so it hasn't seen much rain at all. I returned from my last ride about a month ago, parked the bike with between 40 & 60% charge and it sat in the garage for about 2 weeks. Over those two weeks it was extremely cold out but not freezing in the garage. I then charged the battery (I always disconnect the battery from the motor and display) to 100% and went to go for a ride, the unit would/will not turn on. The battery is fully charged, connectors have been unplugged and replugged in, they're dry and all prongs are all standing. The wiring to the motor makes a circuit but there's zero readings from the power switch or other plugs in the harness. I do not run a brake sensor, shift sensor or throttle. Is my display, selector or controller shot? Are one of these pieces known to work fine and then just not turn back on?
    Any assistance would be greatly appreciated.

    Thank you,

    60% for 2 weeks and not quite freezing should not really be an issue, 40 is getting down there but I still would think still above freezing should be ok. Now if you left it at 40% and it sat frozen for months that would be different. Was it reasonably warm before you charged it? Do you always charge to 100%? How old is this battery and roughly how may charge cycles has it had?

    Do you have a volt meter to verify that you are getting power out of the battery? Its possible that the output could be dead but the charge port could be working and showing full charge.

    If you don't have one may be worth getting one and they are pretty cheap these days. Home improvement and auto parts stores will often have models available as low as $20.


      I'm thinking it was reasonably warm, I was going to go for a ride, so 7C (45F) when I charged to 100%.
      I do not always charge to a 100%, only when going for a longer ride or when wanting to balance the battery pack.
      Battery was purchased in March of 2017 but it's only been used for the past two years. Estimated charge cycles, 80 to 100.
      I have aa volt meter that plugs directly to the battery. It's showing 58.2V.
      I tested at the output as well. I don't know the reading but it showed juice.



        Who did the install of all this? Maybe they actually fused it and the fuse blew. There is a big power surge every time the battery is connected to the BBS, so it can eventually blow a fuse that seems good for all other situations. I didn't see any hand cycles on Lunas page so this seems like a custom build. So anything could be going wrong. Most builds don't have power switches on them. And all the amps usually run thru power switches. So the power switch could have issues. Maybe post pics of what you have so maybe we can spot something of concern.
        Last edited by stts; 01-16-2023, 08:20 PM.


          A local bike mechanic and I did the install.
          No fuses in the system.
          No power switch except the one that comes with Luna's 860C display.

          Luna has followed up on the Trouble Ticket I submitted and provided me with the following troubleshooting link.

          This is troubleshooting a BBSHD/BBS02 <br><br> If you are having issues but the motor is still running please select one of the 2 following links: <br> BBSHD Troubleshooting Random issues on unit still moving (

          From this I see we may have the shift sensor plugged into the throttle or brake connection. This will be the first item I check, plus they show you how to bypass the display, thus being able to rule it out as the problem or not. As said earlier this setup has worked great for about two years, so I'm not thinking it's the way things are plugged in but that a component has failed. We'll see.

          If you see anything obvious in the pics please let me know.


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          • AZguy
            AZguy commented
            Editing a comment
            It's ok to plug the shift sensor into a brake sensor input but for troubleshooting I'd just start with it unplugged and if you have brake sensor unplug them too (although I'd never plug them in - ever - but that's a different discussion ;-} )

          • stts
            stts commented
            Editing a comment
            Great pics. The only thing that looks funny is that the brake wire from the motor looks like it could be crunched before it gets to the connector. After the connector it gets coiled up and tied to the fork tube near that rubber shock. Maybe its a smear of dirt, but if its crunched, it could be a short in there. Its a 3 pin cable so both 5volts and ground is in that cable.Other than that, maybe the 3 button power switch to the display has gone bad. Yours can be unplugged from the display and replaced. Mine has no plug and has to be cut off if it wears out. Or maybe the whole display has quit. You can see if the motor starts up after you do the bypass. If it does, then you know the buttons or display has taken a dump.

          Well, I finally had some time to get back at the handcycle. No crushed wires, it was a dirt smear. I followed the troubleshooting link Luna sent me, testing the display first and voila, it or the selector ended up being the culprit. Unfortunately you can't buy the selector separately and eliminate the cheaper of the two items as the problem so I've ordered a new 860c display. Thank you to those who replied to my request for help, it's greatly appreciated.



          • AZguy
            AZguy commented
            Editing a comment
            Excellent - we appreciate the update... if you do figure out whether it was the buttons or the display itself, let us know if you get the chance

          • stts
            stts commented
            Editing a comment
            Yup, I'm glad I could help you out on this one so you don't waste as much money or time. I bet critics claim it was a fluke that I nailed this one given my experience level, so I'd say even a "lucky guess" can be a useful tool to eBike problems. Time will tell how many other "lucky guesses" I could pull off...

          It ended up being the display. Thanks again. Happy riding!