Controller Blown?

[Trevgrant]

Hi,

I have recently purchased a downhill MTB with a Bafang BBSHD 1000w motor.
It originally came with a backpack battery.
During a ride, I lost all assistance but not power. Screen remained on. On selection of the throttle the bike makes a very slight jerk but nothing more. On inspection one of the cables between motor and battery looked like it had a poor join. I have replaced all cables between the motor and the battery and have a brand new 2nd battery. I have removed the controller and visually checked all connectors.
It could be that the poor cable led to a blown controller, but on inspection it looks fine and wasn't under a big load when it stopped working.
Anyone have any ideas before I order a new controller?
Thanks in advance.

 

[PedalUma]

Did it look like a spark happened at the connection?

 

[Trevgrant]

Did it look like a spark happened at the connection?

No, I just spotted some exposed cable under the sheathing. No sparks or charring anywhere that I can see.

 

[PedalUma]

Try a simple thing first. Turn off the battery. Then turn on the display three times. Then turn on the battery and the display and try it.

 

[Trevgrant]

Try a simple thing first. Turn off the battery. Then turn on the display three times. Then turn on the battery and the display and try it.

Thanks....what does that achieve. Complete drain of power?

 

[PedalUma]

If there is any residual nuttyness in the display it will wipe it for a clean restart without changing the original programing. Sometimes displays need a reboot and it is that simple.

 

[Trevgrant]

Thanks very much. I will give it a try.

 

[Trevgrant]

No luck, unfortunately.....

 

[PedalUma]

Okay. The easiest thing has been eliminated.
Next, do you have a volt meter? Check the battery's output; it could be slightly over charged. If that is the case the system is preserving itself by not starting and only showing the display. 1/2 of one volt will do this. If the display has a USB port this is what you will be using to safely and very slowly take down the bit of overcharge. A USB fan is ideal for this purpose. It could take hours. Secure it well to the handlebar. Office supply and automotive stores have these. I purchased one at a Dollar Store when I had this problem with a new good battery.

 

[Gionnirocket]

Okay. The easiest thing has been eliminated.
Next, do you have a volt meter? Check the battery's output; it could be slightly over charged. If that is the case the system is preserving itself by not starting and only showing the display. 1/2 of one volt will do this. If the display has a USB port this is what you will be using to safely and very slowly take down the bit of overcharge. A USB fan is ideal for this purpose. It could take hours. Secure it well to the handlebar. Office supply and automotive stores have these. I purchased one at a Dollar Store when I had this problem with a new good battery.

He said that the problem started during a ride so I doubt that over_volt would be the problem.
Additionally most BMS's and chargers are better known to not fully charge leaving a battery just under full charge specifications.
These types of problems can be hard to troubleshoot as points to take readings with a meter are few, vital component connections must be maintained and there's no repair manual to spec out voltages at points in the system.
I'd start by unplugging the throttle... Then one brake and then the other brake as I remember reading that it must see at least one to function.. but I'm not positive on this.
In the end parts changing may be the most expeditious solution.The display is probably the cheapest and easiest... Then the controller.
Good luck and let us know how you make out.

 

[Trevgrant]

Thanks all. I have connected the battery to a friends bike and it works perfectly, so don't think its the battery or charge levels.
I have tried disconnecting all cables one at a time and nothing changes.
I have a new controller on order, as I cannot think of anything else to try.
I'll update the post if I find a solution.

 

[Trevgrant]

Update: I have fitted a new controller and everything is now working fine. So must have been a controller issue of some kind. Thanks to all those that tried to assist.