Problem: Bafang BBS01B 250w continues to run after I let throttle off.

[UnclePuncher]

Someone gave me a used BBS01B. Apparently it was used for under 1000 miles 4 years ago.

If I can get it to work I'll use it (and pay him).

I've put it on a frame I'm not currently using. It fits fine. I've rigged it up with the throttle, brakes and head unit (it came with a different head unit, which I also have, but it's damaged).

If I wave a magnet near the wheel/speed sensor it lights up (red led on wheel sensor) and the head unit shows a speed. But the motor doesn't turn. I'm assuming there is a setting somewhere that I need to change but I can't find it.

If I press the throttle the motor turns. If I apply full throttle for more than a second the motor will continue to run once I let off the throttle. The only way I can stop it is by turning the head unit off or applying the brakes (brake cut off levers).


This is the head unit I have:

Bafang Mini Color 500C Display

The Bafang 500C LCD Display is compatible with our Bafang mid-drive motors (BBS01/BBS02/BBSHD) and front hub motors. This is the newest and most compact updated Bafang display. The 500C display has just as many features as the larger DPC18 Full Color with even more battery voltage functionality...

bafangusadirect.com

It also came with this head unit but the screen is scratched and quite dull (but it's still usable):

C961 Display Video and Manual

The C961 Display is one of the available LCD Displays that pairs with our Bafang motors. Below are the C961 Display Programming Video and Bafang C961 Display Manual. Step by Step C961 Display Programming Video: Download the Bafang C961 Display manual here: Bafang C961 Display manual

bafangusadirect.com

I have another ebike and suspected my throttle may be faulty so was going to try my other one. But the julet connectors are reversed on the Bafang.

My suspicion is the controller is faulty but wanted to find out more before I buy one.

Thanks

 

[fechter]

I haven’t heard of that happening with a BBSxx motor. I would suspect the throttle. You could also possibly have a bad connection in the throttle cable. There is one connection on the controller board inside the motor.
Ideally you would want to measure the throttle signal voltage while testing but this is hard due to the connectors.
You could try unplugging and reconnecting the throttle connectors and see if that helps.

 

[bengxe]

Is there a chain and rear wheel on this bike? If not, try unplugging the wheel speed sensor. This also could be normal PAS functionality with no chain slowing the chainring.

 

[Guerney]

If I press the throttle the motor turns. If I apply full throttle for more than a second the motor will continue to run once I let off the throttle. The only way I can stop it is by turning the head unit off or applying the brakes (brake cut off levers).

Water ingress caused this issue on my BBS01B. Stopped happening after I replaced the throttle. This type seems more waterproof. Cheap on AliExpress, check compatibility with seller.

 

[UnclePuncher]

I haven’t heard of that happening with a BBSxx motor. I would suspect the throttle. You could also possibly have a bad connection in the throttle cable. There is one connection on the controller board inside the motor.
Ideally you would want to measure the throttle signal voltage while testing but this is hard due to the connectors.
You could try unplugging and reconnecting the throttle connectors and see if that helps.

Thanks for your help.

I tried pulling the throttle cable whilst it was doing it (running after releasing the throttle). Unfortunately it didn't do anything.

I'll see about testing the throttle connection on the board after I've got hold of another throttle to rule that out.

Thanks again.

 

[UnclePuncher]

Is there a chain and rear wheel on this bike? If not, try unplugging the wheel speed sensor. This also could be normal PAS functionality with no chain slowing the chainring.

There isn't. But I thought it'd make sense to try it with one. Strangely it works much better with them in. It's not all the time but it seems much better.

I'm going to get another throttle and speed sensor and try them (as they're cheap and can be spares).

Thanks.

 

[UnclePuncher]

Water ingress caused this issue on my BBS01B. Stopped happening after I replaced the throttle. This type seems more waterproof. Cheap on AliExpress, check compatibility with seller.


View attachment 355800

Thank you. I've found that one on Ali. I'll order one.

Cheers

 

[UnclePuncher]

Thanks for all your help guys. This really is an excellent and helpful forum. I'd be lost without you guys.

I'll try a few things recommended and report back.

 

[UnclePuncher]

Hey guys. My new throttle arrived. Turns out the old one was faulty. All is working as it should now. Thanks for your help everyone.

I'll update if I get more problems.

 

[fechter]

Great! Thanks for reporting your results.