Bafang BBSHD ??

nemesis03

1 µW
Joined
Jan 9, 2019
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2
The BBSHD motor is starting up for a split second when turning the cranks BACKWARDS while the bike is stationary,has anyone any ideas how this could be happening ?
 
Yes, the sensors are starting the bike when pedaling backwards. Seriously, that’s quite odd. A slight forward motion with high PAS settings, but i backpedal to kill my motor and shift. Polish gear sensor...
 
I tried backwards pedaling on mine and the motor did not run at all. I don't think it should ever do that.
 
It should not do that at all. Possibly something is messed up with one of the PAS sensors. Unfortunately, these are hard to check.
You could try taking off the controller side cover and unplugging and reconnecting the PAS sensor connector and look for pinched wires in there. You probably have to remove the chain ring to do this.

 
I am not sure what the PAS sensor looks at since I have not had mine apart but not much turns when you pedal backwards. The clutch is released in that direction.
 
I found this picture of the sensor and PAS magnet ring. The sensor is just a pair of hall switches on a little board.

One possibility is you have a small piece of magnetic debris stuck to the PAS disk that is false triggering the sensors. It looks like sort of a pain to take apart enough to check.

 
The start-up signal for the PAS was set at 2 so i adjusted it to 3 in the programming and now it is okay.
 
nemesis03 said:
The start-up signal for the PAS was set at 2 so i adjusted it to 3 in the programming and now it is okay.

Thanks for reporting the solution. I don't think I ever messed with that setting.
 
I had this issue when I changed the pass sensor settings when messing around with the programming. If you have a programming cable, go into the settings and make sure the pass sensor timing is not set below the default setting. If default is 10ms set it to that or higher. If set to anything lower, any sudden movement of the crank arms in a backpeddaling mannor will cause a slight jolt forward as the pass sensor kicks in as if you were to normally peddal.
 
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