First E-bike, issues with motor (motor reversed out of nowhere)

Nielsquake

100 µW
Joined
Jun 14, 2022
Messages
8
Hello everyone on the forum, this is my first post here since I am having some issues with my hub motor (the most generic 1kw Chinese one). I got it for 250 euros second hand and it came with all the cables still connected from a working bike so I just attached it to my bike as it was configured.
I got it to run easily enough by connecting a battery pack to it and it was going pretty fast and working well. I switched to a better battery and did some test laps around my area and everything seemed fine until suddenly the motor abruptly stopped the bike (I was going slow so no injuries or anything) and I figured a cable came loose or something and got caught between the spokes. However, upon further investigation I noticed the wheel was spinning fine but now it is in REVERSE!

Now before telling me I hooked up the hall sensor wires wrong or those motor driver cables should be changed you have to realize this change happened during me driving it with no alterations to the wiring. I manually peddled back to my house to inspect and do some research on the issue. I learned that some bike controllers have a build in feature to reverse but this didn't seem to be included on my driver. I also heard some drivers come with a learning feature that can automatically determine the correct hall sensor configuration but this feature also wasn't on my driver!

I just reversed the polarity 2 of 3 of the main motor driver wires and now although it did go forward it now has other issues.

When I throttle it makes a weird noise like a grinding type noise and when I accelerate fast enough this goes away and gets replaced by a kind of rubbing / squeaking noise. This doesn't happen when I pedal manually. Also when I use the throttle it doesn't immediately go faster (doesn't output any wattage) for around a second and then suddenly goes forward. The wattage it gets to after this is also lower then what it was before (700w vs 1040w according to the display)

Funny thing is I found a reddit post about someone with exactly the same issue (new battery, bike runs fine, bike halts, bike is now in reverse mode, change motor driver wires, works but weird sound. His experience was 100% the same as mine and he managed to fix it by just getting a new driver he already had as a spare.

Now I can drop 60 euros on a new driver and hope for the best but I was wondering if anyone here has any idea why this could even happen. If it was an issue with some mechanical part I imagine it must also cause issues while driving manually without the motor being powered yet there is 0 difference from before.

Any help would be much appreciated!

I really made sure none of these features like reverse and the self learning stuff were on here so I think something wonky must have happened internally with the driver module.

The bike still works fine and it goes relatively fast but I'm afraid I might damage the motor itself if I keep using it.
 
The reddit post I was talking about of the guy having the same issue. https://www.reddit.com/r/ebikes/comments/lupiq0/throttle_delay_and_jerking_motor/

Edit: here is another video I found of someone with the same issue. note the sound it makes https://www.youtube.com/watch?v=RsA92rfKM1Y
 
I tried riding it just to see how it would handle it and it does manage to pull me along just fine but the noise it is accompanied by is not very healthy sounding. I only rode it for several meters so I guess it's fine but would any of you think my best bet is trying the new controller idea? Like in that reddit post
 
If it did it without changing anything, maybe you damaged the wires and didn't notice, and they're shorting out. Where they exit from the motor axle is a really common place. Next most common is them melting together at the controller end where they connect the bike wiring harness, esp if it's hidden in a box in the frame.

Usually if it's in the controller itself, it just plain stops running
 
Voltron said:
If it did it without changing anything, maybe you damaged the wires and didn't notice, and they're shorting out. Where they exit from the motor axle is a really common place. Next most common is them melting together at the controller end where they connect the bike wiring harness, esp if it's hidden in a box in the frame.

Usually if it's in the controller itself, it just plain stops running

Hmm could be that this is the case! Do you by chance know of any resource of how these things might be troubleshooted?
 
Voltron said:
Detailed visual inspection is the first step. If you don't know where your controller is, you'll want to find it.

lmao, obviously I know where the controller is but I don't know much about the internal workings of the components. I'm asking about a guide to diagnose potential hall sensor cable failure from the controller to the hub motor. I have done a visual inspection of all cables that I can readily observe but no problems could be identified
 
Lol, just checking, you never know sometimes.

If you're really sure the connectors aren't melting together, or that the bike didn't fall over and smoosh them at the axle, then it's maybe open the controller and see if there's burned smells, or maybe the windings in the motor are shorted?
There's a bunch of threads on here in how to diagnose the actual electrical signals of the Halls with a voltmeter... They should be putting out little 5v pulses as you turn the motor by hand.
Some controllers are dual mode that start using Halls then switch to sensorless at higher rpm, but that's a big maybe if it would make it run backwards if the mode switcher was acting up in the controller?
 
A quick field test for the motor windings is to disconnect the phase wires from the controller, and short 2 out of the 3 of them together and spin the motor by hand. There should be really pronounced cogging resistance in the motor suddenly.
Then you work thru all three combos.
If it's a geared motor you have to turn it backwards to feel it because of the clutch.
And you're sure there isn't a pair of self learning wires still plugged together at the controller maybe?
 
If you switch phase wires to get it running forward, you usually need to switch the hall wires too, or it can run on a false positive combo, which would def cause grinding, and will overheat everything like crazy if you keep running it.
 
There is no grind ing in my case running sensorless, after switching phase wires. Am I at risk of burning up my motor?

No grinding, just normal sensorless noises.
 
Hello everyone on the forum, this is my first post here since I am having some issues with my hub motor (the most generic 1kw Chinese one). I got it for 250 euros second hand and it came with all the cables still connected from a working bike so I just attached it to my bike as it was configured.
I got it to run easily enough by connecting a battery pack to it and it was going pretty fast and working well. I switched to a better battery and did some test laps around my area and everything seemed fine until suddenly the motor abruptly stopped the bike (I was going slow so no injuries or anything) and I figured a cable came loose or something and got caught between the spokes. However, upon further investigation I noticed the wheel was spinning fine but now it is in REVERSE!

Now before telling me I hooked up the hall sensor wires wrong or those motor driver cables should be changed you have to realize this change happened during me driving it with no alterations to the wiring. I manually peddled back to my house to inspect and do some research on the issue. I learned that some bike controllers have a build in feature to reverse but this didn't seem to be included on my driver. I also heard some drivers come with a learning feature that can automatically determine the correct hall sensor configuration but this feature also wasn't on my driver!

I just reversed the polarity 2 of 3 of the main motor driver wires and now although it did go forward it now has other issues.

When I throttle it makes a weird noise like a grinding type noise and when I accelerate fast enough this goes away and gets replaced by a kind of rubbing / squeaking noise. This doesn't happen when I pedal manually. Also when I use the throttle it doesn't immediately go faster (doesn't output any wattage) for around a second and then suddenly goes forward. The wattage it gets to after this is also lower then what it was before (700w vs 1040w according to the display)

Funny thing is I found a reddit post about someone with exactly the same issue (new battery, bike runs fine, bike halts, bike is now in reverse mode, change motor driver wires, works but weird sound. His experience was 100% the same as mine and he managed to fix it by just getting a new driver he already had as a spare.

Now I can drop 60 euros on a new driver and hope for the best but I was wondering if anyone here has any idea why this could even happen. If it was an issue with some mechanical part I imagine it must also cause issues while driving manually without the motor being powered yet there is 0 difference from before.

Any help would be much appreciated!

I really made sure none of these features like reverse and the self learning stuff were on here so I think something wonky must have happened internally with the driver module.

The bike still works fine and it goes relatively fast but I'm afraid I might damage the motor itself if I keep using it.

If this motor is 250 Euros 2nd hand, what is a brand-new 1000W direct drive kit in the UK/Europe? How much does that cost there? I guess we are spoiled in America, a new 1000W direct drive kit here is between $200-250 USD.

Tell us what the display name is if you can see it, maybe take a picture of the 5-pin wire, then I/we can recommend a new controller. Or controller/display together. They are not super expensive.
 
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