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MCM5 v2 84V did I fry my motor?


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Hello all,
today I went for I ride and unfortunately hit a curb unexpectedly hard and returned with a flat tire.
So after 800km it was my first time tearing apart the wheel. 
After a successful replacement of the inner tube I put back the motor and reconnected the motor to the motherboard.
I turned on the wheel and the motor was just vibrating a lot and after a few seconds a spark went around the marked wire and I turned off everything. Kf2TC7z.jpg
Probably I haven't been as careful as I should have been with the isolation of the wires (the photo is made after,when i tried to put it more carefully)
But right now when I power on the wheel there are 4 beeps and the motor doesn't start at all, and also it doesn't turn smoothly anymore (even when turned off completely) but have come internal bumps, check the video https://i.imgur.com/4pklFBC.mp4

Can anybody explain me what happened? Do I need to replace the motor? Also the motherboard?

Thanks a lot

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14 minutes ago, yaro96 said:

Can anybody explain me what happened? 

The spark was most probably an overburdened mosfet which causes a shortcurcuit now across two motor phases.

This causes the motor to not turn free anymore.

This could already happened once you flattened the tire at the curb. Or lateron by bad connection of the hall sensor wires. Possibilities are quite endless...

18 minutes ago, yaro96 said:

Do I need to replace the motor? Also the motherboard?

The motor is most likely still ok - it's on of the most sturdiest parts.

The motherboard contains the mosfets, which switch the currents through the motor coils. And by now, as they are dead short circuit them braking the motor if turned.

So the motherboard needs to be replaced. Replacing the mosfets could be sufficient, but there is quite some probability tgat their driver curcuits are dead, too.

As mentioned before bad hall sensor connections can cause mosfets to fry, the hall sensors within the motor could be damaged or their connections within the motor. But that is less likely.

Btw - Welcome!

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Hmm? Vibrating would suggest that the shell to pedal hangers was not tight. The wheel tries to balance but can’t because LEVEL keeps changing. Sparks after vibrating would suggest that the board lost a chip. Wheel not turning smoothly with power turned off? If the chip is shorted the motor will NOT turn easily. Disconnect the motor wires and see if the wheel turns motor easily. If so the board is likely bad

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Posted (edited)
On 5/7/2021 at 4:05 PM, yaro96 said:

did I fry my motor?

https://i.imgur.com/4pklFBC.mp4

 

No... you fried your board :(

Possible causes:

  • Incorrect connection of the 3 motor cables
  • Electrical shorting during severe vibration
  • Overloading during severe vibration

Severe vibration typically happens if the motor or controller is not mounted very securely to the EUC shell. Even a tiny bit of looseness will cause a huge vibration- if it happens, lay the wheel on its side quickly to cause it to stop, then turn it off and fix the mounting issue.

Your motor is almost certainly OK. Unplug the motor wires from the control board, and it should spin freely again.

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Edited by RagingGrandpa
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it goes without saying: make sure to get the motor wire connections exactly right. I don't know which is which but someone should be able to help.

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  • 1 month later...

So, it happened again...
A new motherboard finally arrived today. After replacing it and booting up the wheel it burned down around the third mosfet, so I guess I fried another motherboard.
Can please anyone confirm if it is the right motor connections? Or did I messed up my markings since the start.
I found that the motor wires are colored under the double sleeve: blue, yellow, green. Is it the correct sequence?
bIsaK62.jpgJi0wBcG.jpg

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Posted (edited)

yep, I found out afterwards
Hopefully I didn't damage the motor

Now I need to find another motherboard, but can't find anywhere in Europe. I guess only AliExpress from China

Edited by yaro96
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I've never been present for that type of board failure... what was it like?

You stood the wheel up, and it vibrated violently? For how many seconds? And then smoke?

Thx

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pfff, frying a MB by interverting phase wire, never saw that with ebike controllers!!

I realize now how lucky I was after changing my MB,
the yellow phase wire of my motor was 3mm longer than the blue, so I ended doing it correctly.

I share in suffering with yaro96 about his bad luck.

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I've changed many e-bike and e-scooter controllers and swapped motors and had to swap around phase wires to get the right combination with the hall sensors. Never an issue. It really is suprising that the board would fry because of this.

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Posted (edited)

@yaro96

Also, make sure you're milking any power left in the wheel after the battery is disconnected (press the power button on several times until the wheel no longer powers on), to prevent any residual charge in the system damaging things on connection. 

I've heard of this damaging boards, more than reversing the motor wires.

You want to always do this step first (disconnecting battery then milking) before taking apart the rest of the wheel or disconnecting any other board components.

Edited by houseofjob
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Yes, it went down quite quickly.
After the boot there were some vibrations, and when I tried to stupidly move the wheel around to see if it balances, there was a big spark near the third mosfet and a cloud of smoke rising from the control board :facepalm:

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10 hours ago, yaro96 said:

Yes, it went down quite quickly.
After the boot there were some vibrations, and when I tried to stupidly move the wheel around to see if it balances, there was a big spark near the third mosfet and a cloud of smoke rising from the control board :facepalm:

:cry2:   

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It is a good old practice to connect a (tungsten) bulb in series with the battery. It is a simple way to limit the amount of current in case of our mistake or defect in electronics.

This is the golden rule of the pyroman: - "always test small-scale chemical reactions first"

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