Bafang BBSO2 motor keeps going

[Kelpie73]

Hi, I have a bbso2 mid drive on a yuba cargo bike. It was recently serviced (regreased and packed) and was working ok for a couple of rides, then suddenly the motor wouldn't cut out when I stopped pedaling and would just keep charging onwards. I can shut the motor off by turning pas down to 0 but once I touch the throttle or pedal, the motor kicks in and doesn't stop. I don't have the brake sensor/cut off on my bike (out of stock when I bought my kit and I seemed fine without it for the past couple of years).

I checked all my cables and connectors, they seem fine, I unplugged my throttle and problem was the same. Hoping someone might recognize this problem, I saw one thread where a similar issue seemed to be a broken pas magnet, but I've looked into that before and it seems that if you had a broken magnet, the pas wouldn't be working at all whereas mine does kick in when I pedal and the throttle activates the motor just fine as well. It just doesn't stop when I stop pedaling! I don't have the tools or a great space to take on a project like opening up the motor but I'm thinking I might have to start figuring it out with this glitchy system

 

[Gionnirocket]

Perhaps they packed too much grease and it worked its way into the PAS sensor and shorted it?
I don't think I've ever heard anyone with this problem before.
Well it seems like a good time to invest in the brake cut outs.

 

[Kelpie73]

Perhaps they packed too much grease and it worked its way into the PAS sensor and shorted it?
I don't think I've ever heard anyone with this problem before.
Well it seems like a good time to invest in the brake cut outs.

Will order them for sure but probably won’t solve the main issue

 

[Gionnirocket]

Will order them for sure but probably won’t solve the main issue

No... And I wouldn't use them in that manner.
Was just highlighting that safety devices aren't necessary, until they are necessary
Did you say that the throttle also causes motor run on.. Or just the PAS?

 

[Dewey]

I read on here from ex-motorcycle riders about the problem of “wide open throttle” or WOT. It happened to me when I moved my handlebar controls once and the throttle was too close to something and stuck open. I had the kit Bafang ebrake levers at that time, since replaced with ebrake sensors on better quality levers. When I wrote up a blog post about my build the EBR webmaster @troehrkasse commented he had seen many DIY folk leave off ebrake sensors which after my experience puzzled me.

 

[Dewey]

It just doesn't stop when I stop pedaling! I don't have the tools or a great space to take on a project like opening up the motor but I'm thinking I might have to start figuring it out with this glitchy system

Does the motor stop if you pedal backwards?

As well as ebrake sensors you can fit a Big Green Button Bafang motor kill switch, made by Wuxing. I used one for a while before I bought a gearsensor. It has a yellow higo connector that replaces one of the ebrake lever connectors, I suggest the right/rear.

Someone on the Endless Sphere forum reported you can open the controller and disconnect the PAS sensor to ride on throttle alone. Bafang BBS motors are quite robust like that, once I accidentally wrapped the speed sensor cable around my kickstand and tore it out of the controller, but on my older 2013 BBS01 I was still able to change PAS levels and ride it as normal, just without the speed and the error 21 code on the display, which since 2017 will cut the motor. I rode it like that for nearly a year before replacing the controller to get my speed display back.