M2 Chinese LCD Burned. Can't start bike

Cybercat · Jul 19, 2022

Dear Experts,

I'm new to this forum and found this forum while googling for a solution to my issue.

I recently purchased front motor hub from Aliexpress and fixed to my bicycle.

https://a.aliexpress.com/_mMlORhC

After about 45km, suddenly the dispaly was frozen. Then I unplugged the battery to reset and now display does not trun on. This happened few times before and reset power worked.

Then I used a jumper to positive and controller lines of the display socket and was able to power up the system without the display. Now power 5V is coming to hall sensors, brakes and pas sensor sockets. But still when I throttle it don't move. Then I tried connecting rx+tx, rx+gnd, tx+gnd but still motor not working.

I have already ordered a 866 display but now I suspect whether the controller is also damaged.

Please advice how to get this running until the new display arrives.

Battery- 36v created with 9 18650 batteries for testing and i was able to run approx 5 6kms with battery only.
Motor controller- Brainpower 500w

Inside M2 dispaly if anyone is interested.

calab · Jul 23, 2022

Do you really really really want a display unit?

Label on your controller says 36/48v 25a, which sell for $20-30 sensorless or sensored, without a display. More things to go wrong and they show up here all the time with non-working display units. Its not even worth the hassle, buy a $10 Cycle computer and be done with it.

E-HP · Jul 23, 2022

It takes 10 cells of 18650 for a 36V battery. You may have other issues going on, so at least fix the obvious ones, so you have less to diagnose.

fechter · Jul 23, 2022

It looks like the battery wire is broken off from the display board. The other wire connections look sketchy too. Was it like that when you took it apart? It might work if you fix the wires.

Cybercat · Jul 25, 2022

E-HP said:
It takes 10 cells of 18650 for a 36V battery. You may have other issues going on, so at least fix the obvious ones, so you have less to diagnose.

It's OK, 37.9V at full charge. 30V cut off by the controller. I want your help to get it running without display.

Cybercat · Jul 25, 2022

fechter said:
It looks like the battery wire is broken off from the display board. The other wire connections look sketchy too. Was it like that when you took it apart? It might work if you fix the wires.

It was broke when I break open the display. Can you please help me to get the controller running without dispaly.

Cybercat · Jul 25, 2022

calab said:
Do you really really really want a display unit?

Label on your controller says 36/48v 25a, which sell for $20-30 sensorless or sensored, without a display. More things to go wrong and they show up here all the time with non-working display units. Its not even worth the hassle, buy a $10 Cycle computer and be done with it.

Sorry if I misunderstood your comment. Do you think the issue is with the controller? As of now, I checked all the voltages and it out put them correctly. Only problem is getting current to phase without the display. Looks like by default its in 0th gear. Do you have any other thoughts to troubleshoot the controller? My goal here is to get the controller running at least in 1st gear until a dispaly arrive.

calab · Jul 25, 2022

No, I am sorry. The tone was wrong of me. Its been one hell of a week.

The issue could be many things, thats the problem. Lots of great advice posted here. I am out.

Cybercat said:
calab said:

Do you really really really want a display unit?

Label on your controller says 36/48v 25a, which sell for $20-30 sensorless or sensored, without a display. More things to go wrong and they show up here all the time with non-working display units. Its not even worth the hassle, buy a $10 Cycle computer and be done with it.

Click to expand...

Sorry if I misunderstood your comment. Do you think the issue is with the controller? As of now, I checked all the voltages and it out put them correctly. Only problem is getting current to phase without the display. Looks like by default its in 0th gear. Do you have any other thoughts to troubleshoot the controller? My goal here is to get the controller running at least in 1st gear until a dispaly arrive.

amberwolf · Jul 26, 2022

Cybercat said:
Looks like by default its in 0th gear. Do you have any other thoughts to troubleshoot the controller? My goal here is to get the controller running at least in 1st gear until a dispaly arrive.

Without a display to process the button inputs and send commands to the controller, you can't change from the controller's default power-on assist level, whatever that happens to be.

You can run most of the display-type controllers "headless", but they only operate in their default mode this way.

Since most of them are only turned on by the display itself, then like you have already done, you can bypass this by connecting a wire from the battery positive output pin on the controller's display connector back to it's keyswitch / ignition / KSI / powerswitch wire. (the display has internal electronics to do that when you press the power button on the display),

If the controller doesn't operate with that jumper wire, then it is either not capable of running headless, or it isn't working (broken, defective, etc).

If the controller works, but you can't use the system for your purposes in the default assist level, then you'll need a compatible display (one just like the original gives the most chance of that) to change the assist level.

If you really need it to operate without a display, then if you can find someone with the same controller and display, and "record" the serial data from their display when the assist level is changed, you could use that to make a little MCU device (arduino, etc) that plays that back when a button is pressed, without even knowing what the data is. (assuming there is no back-and-forth between the controller and the display in this particular process).

Cybercat · Jul 27, 2022

amberwolf said:
Cybercat said:

Looks like by default its in 0th gear. Do you have any other thoughts to troubleshoot the controller? My goal here is to get the controller running at least in 1st gear until a dispaly arrive.

Click to expand...

Without a display to process the button inputs and send commands to the controller, you can't change from the controller's default power-on assist level, whatever that happens to be.

You can run most of the display-type controllers "headless", but they only operate in their default mode this way.

Since most of them are only turned on by the display itself, then like you have already done, you can bypass this by connecting a wire from the battery positive output pin on the controller's display connector back to it's keyswitch / ignition / KSI / powerswitch wire. (the display has internal electronics to do that when you press the power button on the display),

If the controller doesn't operate with that jumper wire, then it is either not capable of running headless, or it isn't working (broken, defective, etc).

If the controller works, but you can't use the system for your purposes in the default assist level, then you'll need a compatible display (one just like the original gives the most chance of that) to change the assist level.

If you really need it to operate without a display, then if you can find someone with the same controller and display, and "record" the serial data from their display when the assist level is changed, you could use that to make a little MCU device (arduino, etc) that plays that back when a button is pressed, without even knowing what the data is. (assuming there is no back-and-forth between the controller and the display in this particular process).

Wow. Thanks. :bigthumb:

Cybercat · Jul 27, 2022

calab said:
No, I am sorry. The tone was wrong of me. Its been one hell of a week.

The issue could be many things, thats the problem. Lots of great advice posted here. I am out.

Cybercat said:

calab said:

Do you really really really want a display unit?

Label on your controller says 36/48v 25a, which sell for $20-30 sensorless or sensored, without a display. More things to go wrong and they show up here all the time with non-working display units. Its not even worth the hassle, buy a $10 Cycle computer and be done with it.

Click to expand...

Sorry if I misunderstood your comment. Do you think the issue is with the controller? As of now, I checked all the voltages and it out put them correctly. Only problem is getting current to phase without the display. Looks like by default its in 0th gear. Do you have any other thoughts to troubleshoot the controller? My goal here is to get the controller running at least in 1st gear until a dispaly arrive.

Click to expand...

No problem, thank you so much for stepping in to help.

Cybercat · Aug 4, 2022

After a long wait, S866 display arrived. Something interesting happened with it so thought of posting here.

I received communication error after connecting it to controller. I did all the suggestions in this forum and nothing worked.

Finally i noted that the data lines are in different colour wires on the display connector. yellow is for utility, green and blue are data. All the communication errors were gone after I changing the wires and now all works well. Bit strange. Hope this helps some.

TommyCat · Aug 4, 2022

Cybercat said:
Finally i noted that the data lines are in different colour wires on the display connector.

Did you do this by opening up the display and tracking the wires to the PC board terminals?

What a GREAT catch! I salute you for the find, and posting.

Cheers,
T.C.

M2 Chinese LCD Burned. Can't start bike

Cybercat

1 mW

calab

1 MW

E-HP

10 GW

fechter

Administrator

Cybercat

1 mW

Cybercat

1 mW

Cybercat

1 mW

calab

1 MW

amberwolf

Administrator

Cybercat

1 mW

Cybercat

1 mW

Cybercat

1 mW

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TommyCat

10 kW

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