Bafang front hub motor stopped working

[Murad]

Hey guys, Ive got some issues here I could use some help with. I have a Bafang G31.250.D front hub motor that does nothing. It doesnt give any power and it also doesnt register the speed when cycling. The display (C600) gives an error 9, "Panel Communication Abnormality", I find that a bit vague. I have swap-tested the display, the battery and the controller, those are not the problem. All the cables/connectors I found seem to be fine as well.

Was hoping someone here could point me in the right direction? Thank you in advance!

Edit; the bike was pre-built and worked fine for 10k km.

 

[E-HP]

What was happening when it failed?

 

[amberwolf]

What specifically happened between the time it worked, and the time it didn't? Sometimes that can point to where the problem is.


Some of the C600 manuals (like Dapu) show error 9 as overvoltage, > 45v. What voltage is the battery?


If it's really a comm error problem, then that is something between display and controller, where one can't talk to the other, usually that the display is not receiving any info from the controller.

Sometimes that's because the display hasn't turned the controller on, meaning the controller isn't receiving battery voltage on the Lock / KSI line, so it doesn't have power to the LVPS that makes 5v/etc to run things from. If you can set your voltmeter to 20vdc, put the black lead to battery negative or any other system ground wire, then disconnect your throttle or PAS sensor, turn the system on, and on the controller side of that connector put your red meter lead on each of the three pins in turn. At least one should read 5v. If none do, the controller is probably not being turned on.

If that's the case, there is some connection or wiring problem between display and controller on the lock line, *or* the transistor inside the display that does the switching for this has failed, like in this thread:

The dreaded Error 30 (communication error) [Resolved]

I'm helping a neighbor diagnose his bike, which displays an Error 30 a few moments after you power on the bike. I found dozens of posts about this particular error across several websites, videos on YouTube, and a troubleshooting guide on the bike manufacturer's website. So, I really didn't...

endless-sphere.com

Sometimes a comm failure is literally a comm failure--something has gone wrong with the TX or RX between the two, either a transciever failure inside either controller or display (or both), or a connection / wire problem. Doesn't even have to be a broken wire--it can just be poor contact from a spread pin inside a connector, or corrosion,etc.

 

[Murad]

What was happening when it failed?

The motor had been faltering for 2 days, meaning power came and went randomly. After the 2 days it stopped giving power at all.

 

[Murad]

What specifically happened between the time it worked, and the time it didn't? Sometimes that can point to where the problem is.


Some of the C600 manuals (like Dapu) show error 9 as overvoltage, > 45v. What voltage is the battery?


If it's really a comm error problem, then that is something between display and controller, where one can't talk to the other, usually that the display is not receiving any info from the controller.

Sometimes that's because the display hasn't turned the controller on, meaning the controller isn't receiving battery voltage on the Lock / KSI line, so it doesn't have power to the LVPS that makes 5v/etc to run things from. If you can set your voltmeter to 20vdc, put the black lead to battery negative or any other system ground wire, then disconnect your throttle or PAS sensor, turn the system on, and on the controller side of that connector put your red meter lead on each of the three pins in turn. At least one should read 5v. If none do, the controller is probably not being turned on.

If that's the case, there is some connection or wiring problem between display and controller on the lock line, *or* the transistor inside the display that does the switching for this has failed, like in this thread:

The dreaded Error 30 (communication error) [Resolved]

I'm helping a neighbor diagnose his bike, which displays an Error 30 a few moments after you power on the bike. I found dozens of posts about this particular error across several websites, videos on YouTube, and a troubleshooting guide on the bike manufacturer's website. So, I really didn't...

endless-sphere.com

Sometimes a comm failure is literally a comm failure--something has gone wrong with the TX or RX between the two, either a transciever failure inside either controller or display (or both), or a connection / wire problem. Doesn't even have to be a broken wire--it can just be poor contact from a spread pin inside a connector, or corrosion,etc

Thank you, thats a lot of information! Will try and get back.

To answer your question, it didnt just stop working overnight, the bike was altering in giving power and randomly shutting off for 2 days, after which it stopped giving power completely. The battery is a 36v 300wh.

 

[amberwolf]

That's normally a problem with a connection somewhere, most often a damaged wire at the back of a connector or a bend, etc. Uusallly this is inside the cabling and not externally visible.

What happened just before the faltering problem?

There's usually a root cause for connection issues, such as bumps, crashes, falls, handling, modifications, moisture, heat/cold/weather, etc. Knowing circumstances around the time of a problem start (or previous to it) can help lead to the actual fault. (and help find ways to ensure it doesn't happen again).