BBS02 Thumb Throttle & Speed Sensor Problem

[Provokatoren]

Hi,

I bought a Bafang BBS02 750W kit from GreenBikeKit.com a few months ago. Installed it on my bike and everything worked just fine. Then all of a sudden the thumb throttle and the speed sensor stopped working. They both stopped working at the same time. I did not do anything out of the ordinary when it happen, was just about to bike home form the office.

However the motor is still working, I can use the PAS just fine, but the thumb throttle and speed sensor is not working. My display gives me the error 21 after 50-100 meters when using PAS. I can still switch PAS levels, although the display keeps flashing the error code 21. The red light on the speed sensor is not lit like it was when everything was working.

I got in contact with GreenBikeKit who sent me a new thumb throttle and speed sensor. I installed these, but no luck. The problem was still there. That got me thinking it might be the controller that is the problem. So I order a new controller, (750W 48V 25a), and swapped it with my old controller. Still, the thumb throttle and speed sensor is not working. Although the motor itself is working like before (PAS ok). I was absolute sure that with a new controller all would work just fine, but no, that was not the case. How is the possible? What could be the cause of the problem? Could the motor itself have anything to do with this?

New controller, new throttle, new speed sensor, but same problem. I have checked the connectors, all seems fine. Any ideas?

Thanks in advance.

 

[Ykick]

Try another display and of course carefully qualify every wire run for damages.

 

[sather]

Swapping the controller should have taken care of the speed sensor issue, since it is connected directly. Check your magnet/sensor placement. The throttle problem could be the wiring harness or display. I have had two BBSXX wiring harnesses, one display and one throttle fail. (from 5 BBSxx motors with heavy use)

Empowered Cycles offers this Bafang troubleshooting kit, you just pay for what you use:
https://www.empoweredcycles.com/collections/8fun-bafang-bbs02-accessories/products/troubleshooting-kit-bafang-bbs02-bbshd
"Kit includes the items that are most likely to fail such as the motor controller, display, throttle, wiring harness, and brake cutoff switches. Swap out parts until your kit is operational again. Keep the part/s that fixes it, send everything back plus the defective part/s for confirmation of defect. Two way insured shipping is included in kit price USPS priority (25$) return shipping label included. You will be refunded for the returned parts when testing confirms returned items are still in good working order free of defects. Kit comes with the C961 monochrome, and the DPC-14 full color display available for purchase if you wish to upgrade."

 

[Provokatoren]

Thanks for your input. I will get a new display and see is that helps with the throttle problem. How is the thumb throttle and display connected, i.e. how could the display stop the throttle from working? I have a new speed sensor that I tried after swapping the controller, but it did not work. If it is the magnet that is broken, should not the speed sensors red light be on regardless?

 

[Ykick]

BBSXX display seems to convert throttle voltage signal into an unknown (to me) serial communication protocol to controller over TX/RX wiring. Make sure all the cabling is in good condition. Check that tie wraps aren't cinching the wires too tightly and perhaps creating a problem along the wire run?

There’s also some interaction with the brake cutout circuits so those sometimes effect throttle operation as well. Try a test with the brake cutouts unplugged?

Speed sensor red LED alternates on/off as the wheel magnet passes over it so you won’t always see the LED on. But when under normal operation any magnet passed over the sensor should change the state of the sensor input.

True, the speed sensor is connected to the controller but it might be disabled if there’s a display/throttle/ebrake problem?

I’m still learning the “Bafang way” with these units sorry I can’t be more help. Good luck…

 

[Provokatoren]

I've now tested the following:

Started my BBS02 using the USB configuration cable, i.e. disconnected the display and connected the BBS02 to my computer using the USB cable. This started the BBS02, moving the pedals got the motor going as usable meaning the BBS02 was on and the PAS active. However, the throttle still was not working. So I have a new controller (with new wiring), new throttle and cut the display out of the equation - still - the damn throttle will NOT work. The only thing left now is the motor itself, but that could not have anything to do with it, right? Also, I could have received a bad controller, but the odds of that, a new controller with the exact same problem as my old, is to far of the scale. The same goes for the new throttle.

I guess there is no use in buying a new display?

 

[dustNbone]

It really sounds like a problem with the wiring between the throttle and the controller.

 

[Provokatoren]

It really sounds like a problem with the wiring between the throttle and the controller.

Is there way to test that?

 

[DuncanS]

I had an issue with a throttle not working. I replaced the throttle but the issue remained. Then I remembered I had fiddled with the large 8 pin connector from the motor. When I put it back together I had bent the throttle pin. After taking this apart and re aligning the pin, the throttle worked as it should.

Duncan

 

[Provokatoren]

I had an issue with a throttle not working. I replaced the throttle but the issue remained. Then I remembered I had fiddled with the large 8 pin connector from the motor. When I put it back together I had bent the throttle pin. After taking this apart and re aligning the pin, the throttle worked as it should.

Duncan

Thank you for your input. I have now done a continuity test with a multimeter, and I can now verify that all 3 pins in the throttle connector corresponds to 3 pins in the 8 pin connector that is in the other end. This should rule out the wire harness. Is there any test I could do with a multimeter while the BBS02 is running?