BAFANG M560 MOTOR JITTERING

[George Kinsey]

Hello everyone i am new to the bike community and i have recently brought a second hand bike with a m560 bafang mid drive motor in it.
It was riding perfectly first couple months and i ride pretty vigorously, but my motor has started getting stuck on something inside while its trying to accelerate and makes a horrible noise of throwing a wrench into a gear and i thought it might be a derailer problem as maybe its the swing arm is bent so the chain cathes and so on but i got my bike back today and again a few minutes later it started happening again.
i am not at all there when it comes to electronics but it feels like a belt inside the motor has to much slack causing it to catch in itself and jam but i do not want to take it apart as i have no clue what im doing and cant find any information about this problem online.
thank you for reading that long story and any help would be much appreciated thank you very much!!.

 

[cyclebuddy]

...and i ride pretty vigorously...

This may or may not be your problem, but it does result in Bafang torque sensor mid-motors like your M560 stuttering...

I have a Bafang M400 on a bike that uses smaller 10.4Ah batteries... when ridden "vigorously" and the battery is below full capacity, you can reach a state where the battery starts sagging to meet demand from the motor. What results is a state of rapid stuttering from the motor, and the instant remedy is to back-off pedaling quite so hard which is demanding more power from the motor than the battery can cope with. Note the battery stays on - it's the controller that's very rapidly cutting and restoring power, not the battery.

What's happening in my case is with my battery the LVC is pre-set in the BMS to 28v on the 36v battery. The LVC of the controller is by default higher at 32v. Aggressive pedaling makes the motor demand more than the battery can still give in its partially depleted state which makes the battery sag below the controller LVC, and that makes the controller cut-out. That cut-out gives the battery the opportunity to recover and the controller restores power to the motor... and for as long as you keep demanding so much power (pressing on the pedals so hard) you get this really rapid stuttering - yes, it does feel like a mechanical issue, but (at least in my case) isn't.

What I'm getting to is that - if this is your issue - your battery is probably at least partially knackered - or at least no longer capable of delivering the high levels of current your quite powerful M560 is demanding when being ridden hard. When it next happens, try pedaling less forcefully and demanding so much and see if the problem disappears.

 

[saneagle]

The above is a plausible explanation, but if the battery is good and it happens when the battery is full, it would do that if the phase wire connectors are loose, which has a high probability if the previous owner did something with the controller, like replaced it.

 

[George Kinsey]

This may or may not be your problem, but it does result in Bafang torque sensor mid-motors like your M560 stuttering...

I have a Bafang M400 on a bike that uses smaller 10.4Ah batteries... when ridden "vigorously" and the battery is below full capacity, you can reach a state where the battery starts sagging to meet demand from the motor. What results is a state of rapid stuttering from the motor, and the instant remedy is to back-off pedaling quite so hard which is demanding more power from the motor than the battery can cope with. Note the battery stays on - it's the controller that's very rapidly cutting and restoring power, not the battery.

What's happening in my case is with my battery the LVC is pre-set in the BMS to 28v on the 36v battery. The LVC of the controller is by default higher at 32v. Aggressive pedaling makes the motor demand more than the battery can still give in its partially depleted state which makes the battery sag below the controller LVC, and that makes the controller cut-out. That cut-out gives the battery the opportunity to recover and the controller restores power to the motor... and for as long as you keep demanding so much power (pressing on the pedals so hard) you get this really rapid stuttering - yes, it does feel like a mechanical issue, but (at least in my case) isn't.

What I'm getting to is that - if this is your issue - your battery is probably at least partially knackered - or at least no longer capable of delivering the high levels of current your quite powerful M560 is demanding when being ridden hard. When it next happens, try pedaling less forcefully and demanding so much and see if the problem disappears.

Yes it does sound like a similar problem but it happens even when i am going slow and pedaling up a hill i think it’s something to do with the actual motor underneath the frame.

Whatever makes the motor spin/crank i think is broken or has to much slack and needs tightening.

but no bike shops near me work on bafang batteries as i called up five shops none do anything to do with bafang so am new to this with little knowledge of how to dismantle and restore the motor.

 

[cyclebuddy]

...it happens even when i am going slow and pedaling up a hill...

Speed has nothing to do with it. It's about how much energy you're trying to pull from the battery. Going up hills requires quite a bit of energy because by definition you're still pushing on the pedals even if in a lower gear and spinning a bit faster. It's pushing on the pedals that triggers the torque sensor that determines how much power the motor gives and therefore how much it's trying to draw from the battery.

Try cycling up a hill with the motor turned off and see if it still does it.

PS: The controller is in the motor.

 

[guerney]

Is there a voltage readout on your display, or can you switch to it if not? If it's the same phenomenon, I've experienced it with my Bafang BBS01B mid-drive, on the very rare occasion when I'm down to lithium fumes at very low battery a sort of whirry scritching with no assistance uphill, because the battery is incapable of supplying enough power, evident by very low voltage showing on the display. Triggers the Low Voltage Cutoff programmed in the controller eventually.

 

[saneagle]

Yes it does sound like a similar problem but it happens even when i am going slow and pedaling up a hill i think it’s something to do with the actual motor underneath the frame.

Whatever makes the motor spin/crank i think is broken or has to much slack and needs tightening.

but no bike shops near me work on bafang batteries as i called up five shops none do anything to do with bafang so am new to this with little knowledge of how to dismantle and restore the motor.

The slower the motor turns, the more current it draws, so any connection or battery issues happen at low speed, not high speed.

 

[matthewslack]

Two things to try:

1. On a hill, does the issue show itself only at low cadence in a highish gear, or does it show even at higher cadence in bottom gear?

2. Presumably the Bafang system has multiple assistance levels? If you go down to a lower level when the problem occurs, does it stop?

If it is always there no matter how hard the motor is working and so regardless of current demanded from the battery then... connection issue is likely.

 

[George Kinsey]

Two things to try:

1. On a hill, does the issue show itself only at low cadence in a highish gear, or does it show even at higher cadence in bottom gear?

2. Presumably the Bafang system has multiple assistance levels? If you go down to a lower level when the problem occurs, does it stop?

If it is always there no matter how hard the motor is working and so regardless of current demanded from the battery then... connection issue is likely.

i will try out all things you have told me and thank you all for the help its really amazing, so happy you guys are helping i will try out all said things when im back from work and let you all know how it goes and thanks again.!!!

 

[George Kinsey]

Is there a voltage readout on your display, or can you switch to it if not? If it's the same phenomenon, I've experienced it with my Bafang BBS01B mid-drive, on the very rare occasion when I'm down to lithium fumes at very low battery a sort of whirry scritching with no assistance uphill, because the battery is incapable of supplying enough power, evident by very low voltage showing on the display. Triggers the Low Voltage Cutoff programmed in the controller eventually.

nope it has been happening at full battery, low battery and medium charge. i sadly do not have a voltage reader on my display, it happens as soon as i pedal, when on flat or slight hill it is fine but if i try to pedal fast after a stopping at a light or ect then it jams and or switching gears. it does this almost every time i pull off and sometimes does it when im in a higher gear going up hill. thank you for your response and any help would be greatly appreciated thanks a lot.!!!

 

[George Kinsey]

Is there a voltage readout on your display, or can you switch to it if not? If it's the same phenomenon, I've experienced it with my Bafang BBS01B mid-drive, on the very rare occasion when I'm down to lithium fumes at very low battery a sort of whirry scritching with no assistance uphill, because the battery is incapable of supplying enough power, evident by very low voltage showing on the display. Triggers the Low Voltage Cutoff programmed in the controller eventually.

this has happened before though and around the time it started to have these problems is there any way i can re rest my voltage or is it done automatically when the battery is fully charged again ?. thank for your help also!!

 

[George Kinsey]

Two things to try:

1. On a hill, does the issue show itself only at low cadence in a highish gear, or does it show even at higher cadence in bottom gear?

2. Presumably the Bafang system has multiple assistance levels? If you go down to a lower level when the problem occurs, does it stop?

If it is always there no matter how hard the motor is working and so regardless of current demanded from the battery then... connection issue is likely.

Thank you all so much for the help and would anyone know anyone around brighton and hove or surrounding areas that could fix or even just have a nose at my bike as i am a complete novice when comes to this all though am very interested to learn. thanks to you all so much i cant say it enough!!!

 

[George Kinsey]

This may or may not be your problem, but it does result in Bafang torque sensor mid-motors like your M560 stuttering...

I have a Bafang M400 on a bike that uses smaller 10.4Ah batteries... when ridden "vigorously" and the battery is below full capacity, you can reach a state where the battery starts sagging to meet demand from the motor. What results is a state of rapid stuttering from the motor, and the instant remedy is to back-off pedaling quite so hard which is demanding more power from the motor than the battery can cope with. Note the battery stays on - it's the controller that's very rapidly cutting and restoring power, not the battery.

What's happening in my case is with my battery the LVC is pre-set in the BMS to 28v on the 36v battery. The LVC of the controller is by default higher at 32v. Aggressive pedaling makes the motor demand more than the battery can still give in its partially depleted state which makes the battery sag below the controller LVC, and that makes the controller cut-out. That cut-out gives the battery the opportunity to recover and the controller restores power to the motor... and for as long as you keep demanding so much power (pressing on the pedals so hard) you get this really rapid stuttering - yes, it does feel like a mechanical issue, but (at least in my case) isn't.

What I'm getting to is that - if this is your issue - your battery is probably at least partially knackered - or at least no longer capable of delivering the high levels of current your quite powerful M560 is demanding when being ridden hard. When it next happens, try pedaling less forcefully and demanding so much and see if the problem disappears.

and yes this does sound really similar but it happens even when im not pedaling hard but if in a high gear if i stay in a really low gear then everything is much better and only stutters on if i burst off like an f1 car but when i go up gears it happens much more frequently. thanks for your input i really appreciate it !!!

 

[saneagle]

Having another think about it, you might be suffering from chain suck. Try tensioning the derailleur with the B-screw to see if it makes it better. If it does, you'll need to look for a more permanent solution.

 

[matthewslack]

Another thought: can you estimate your preferred cadence (pedal rpm)?

Anything below 60 is slower than motor will expect and could have an effect.

Also: get someone who has a Bosch/Yamaha/Shimano bike to ride it and see what they think.

 

[George Kinsey]

Another thought: can you estimate your preferred cadence (pedal rpm)?

Anything below 60 is slower than motor will expect and could have an effect.

Also: get someone who has a Bosch/Yamaha/Shimano bike to ride it and see what they think.

definitely over 60 rpm as i love to get places fast.
i will get my friend to try it out who has a kalkoff.

if you know anyone who works on bafangs im happy to travel and pay good money.

also if this helps it feels like its a reaction problem because when i pedal it ever so slightly feels like a delay and then it gives power and thats when it gets stuck.

thank you both for your consistent help you are much appreciated !!!!

 

[George Kinsey]

Having another think about it, you might be suffering from chain suck. Try tensioning the derailleur with the B-screw to see if it makes it better. If it does, you'll need to look for a more permanent solution.

that’s exactly what i thought it was as that is what it feels like i really feels like something is loose or snapped but im scared to take it apart and re attach everything as im not to fond of my own electrical capabilities haha but i got the derailer properly looked at and completely fixed and it was not the problem at all. but thank you very much none the less !!

 

[saneagle]

that’s exactly what i thought it was as that is what it feels like i really feels like something is loose or snapped but im scared to take it apart and re attach everything as im not to fond of my own electrical capabilities haha but i got the derailer properly looked at and completely fixed and it was not the problem at all. but thank you very much none the less !!

Chain suck happens at the chainwheel. The solution is either a chain suck preventer or adjusting the chain tension. You adjust the chain tension with the B-screw in the derailleur, which takes 3 seconds with a screwdriver. Wind it in several turns (count them) and see if anything improves. If it doesn't, wind it back the same number of turns and look elsewhere.

The problem we have is that we have no idea of what you're actually experiencing. Chain suck makes a bit of a bang, like someone's thrown a spanner in your spokes. Electrical problems make more of a grinding noise, like the internal gears aren't meshing properly and are jamming.

 

[George Kinsey]

Chain suck happens at the chainwheel. The solution is either a chain suck preventer or adjusting the chain tension. You adjust the chain tension with the B-screw in the derailleur, which takes 3 seconds with a screwdriver. Wind it in several turns (count them) and see if anything improves. If it doesn't, wind it back the same number of turns and look elsewhere.

The problem we have is that we have no idea of what you're actually experiencing. Chain suck makes a bit of a bang, like someone's thrown a spanner in your spokes. Electrical problems make more of a grinding noise, like the internal gears aren't meshing properly and are jamming.

yes could be an electrical problem as that is exactly what it sounds like, like a grinding and the gears aren’t catching eachother but i will try that also tomorrow before i cycle to work.

Now if it is an electrical problem i know absolutely nothing about fixing bike batteries so should i buy a new motor completely as i have called up 5!! sounding bike shops and none of them work on bafang batteries as they say they cant do anything to do with there internal diagnostics.

Is there any special bafang fixers haha or am i screwed lol, and again thank you for all the help seriously !!

 

[George Kinsey]

yes could be an electrical problem as that is exactly what it sounds like, like a grinding and the gears aren’t catching eachother but i will try that also tomorrow before i cycle to work.

Now if it is an electrical problem i know absolutely nothing about fixing bike batteries so should i buy a new motor completely as i have called up 5!! sounding bike shops and none of them work on bafang batteries as they say they cant do anything to do with there internal diagnostics.

Is there any special bafang fixers haha or am i screwed lol, and again thank you for all the help seriously !!

which is brighton hove if it doesn’t display it on my user.