Display powers off however PAS and throttle still work...

[derangd]

Hello, I am running a Bafang BBS02 48/750. I have been using a 500C display which would lose power and stop the motor from running. It seemed like a loose wire because I could wiggle it and see the display shut down. Usually I could either disconnect a plug (display or harness) re connect and it would flash right up. When it would no longer turn back on I swapped my 965 display in. I had basically the same problem. I also swapped out the harness for a new one and replaced the controller as well. 500C would not power on but 965C does. If I power off the 965 it will not start up unless I do the plug thing, or switch my battery off and on. The thing is that now the bike functions without the display being switched on, both PAS and throttle. Another thing I discovered is that if I spin the cranks backwards the motor will attempt to lurch forward. My next guess would be the motor core but I'd rather not drop the money on something that may not work. If anyone has any advice I be much obliged.

 

[E-HP]

My Honda dealer tries a similar approach. Sun roof not working? Replace the motor. Not right away of course; then suggest replacing anything else they can think of first, and maybe an oil change too.

 

[E-HP]

The thing is that now the bike functions without the display being switched on, both PAS and throttle.

Do the controls to change PAS levels still work as well?

 

[derangd]

The thing is that now the bike functions without the display being switched on, both PAS and throttle.

Do the controls to change PAS levels still work as well?

No, when the display does not function I have no control over levels but it seems set at full power, level 5 (9).

 

[derangd]

Hate to say it but...since you have replaced all the likely culprits, it probably is the motor/stator/hall effect sensors.
Reason for this conclusion is...the problematic, spin the crank backward which tells the bike to lurch forward.
Your old and now new controller isn't liking the signal 'from your motor' which is shutting off the display.

You could try another battery aka BMS but...doesn't address the lurching forward scenario.
Same characteristic with different displays albeit only slightly different...controller is powering off both displays you tried.

Last things to try:
Check error codes in your display under the hidden menu. If you can't get in, try password 1919 under advanced settings.
Before you default to going inside the motor, disconnect your throttle, brake sensor if you have and gear sensor if you have one.

Other thing you want to address is your speed sensor. Check magnet gap and the sensor LED lighting up on every wheel rotation.

Hope that makes sense. An old adage in troubleshooting. Always try the simple stuff first and then progressively go deeper due to expenditure of time and money. Even if its a stator, if you can turn a wrench and a screwdriver, not a big tear up and less money than you have already thrown at it. Now you have a backup controller and display which btw is a good and not bad thing. If you go deep into the motor, replace the nylon gear pre-emptively as preventive maintenance.

Please tell us how many miles on it, if you have ever opened the motor and added grease and if so what kind of grease. Tell us how you ride the bike...aggressive, or easy....hard up hills or not.

Thanks for the response. I do not get any error codes at all. The speed sensor is in the right position and measures speed when display functions.
I use my bike alot, maybe 20-30km daily doing uber deliveries. I try to balance speed with efficiency and not ride hard or burn out from standstill. There may be close to 2000km on this motor.
The issue started early spring but never really happened often, just lately has become troublesome.
I may end up buying the entire motor as the cost of a core is about 2/3's of a new motor.

Also thanks to everyone who responded, I'll check back in once the problem is solved.

 

[E-HP]

The thing is that now the bike functions without the display being switched on, both PAS and throttle.

Do the controls to change PAS levels still work as well?

No, when the display does not function I have no control over levels but it seems set at full power, level 5 (9).

When you say you had the same problem when you swapped out the display, does that include being able to get it working by wiggling the wires?

 

[derangd]

The original display, 500C would shut off when the cable was bent a certain way, but with the replacement 965 it would stay on when moving the cable until whatever decided to shut it off. Now the 500 won't power on at all, but the 965 will.

 

[derangd]

Just ordered a new kit, they are on sale at Aliexpress so should have things up and running in a week or so.

 

[E-HP]

The original display, 500C would shut off when the cable was bent a certain way, but with the replacement 965 it would stay on when moving the cable until whatever decided to shut it off. Now the 500 won't power on at all, but the 965 will.

It could be that there were two issues going on, and the first display that had a bad cable, cycled things on and off when wiggling it. It could that the act of cycling it is what brings the display back, so for the second display, that doesn't have a bad cable, cycling things on and off reconnects it. Seems the old unit is finally kaput as far as the cable is concerned.

PS. Given that you've replaced almost everything, I would go ahead and replace the speed sensor as well, even it it's working when the display is working. Hard to tell if it is when the display isn't. Cheaper than a motor.

 

[derangd]

I'm really impressed by the quick responses I got here. For now I have a new motor kit ordered with all the accessories plus a new display. I'll pull the old motor and when time and money allow will install a new core to see if that brings everything back to proper working order. That way I'll have doubles of everything in case something fubars on me. Thanks for all the tips.
D