Problem with Bafang mid drive motor

[Aaron]

Hi
I am new to this thread as well as ebikes and need some help please.
I am trying to build a plywood e-bike. I have bought a Bafang M400 mid drive motor and from a separate company a battery, display, and cables.
I have connected everything up (battery, speed sensor, display). It is a very cheap display that only shows battery level and power assist level. When I turn it on It shows a full battery and I can increase and decrease the assistance level, but there is absolutely no power from the motor. I have checked and rechecked the connections, how can I diagnose the problem. I have a multi meter but little electronic knowledge.
Thanks for reading and any answers

 

[major masingil]

Hi Aaron, I'm throwing guesses out there. Troubleshooting this way is tough. I don't know anyrhing about the bafang M400. I'm assuming the battery is charged. Does it have a separate throttle, or is it a peddle assist only type of motor? Maybe the stock settings on your controller are messed up so the motor is never getting power to the wheels? Check out the videos on youtube about changing/modifying your controller settings. You will get some good info in those. I used the Speeed App to change the settings on mine, but you need an android phone for that App. I assume you're not seeing any error codes on the controller? Do you have pictures of your install? They should focus on how things are connected to each other.

 

[MWRider]

Is your speed sensor functioning properly? Correct alignment of magnet? Red LED should flash.

 

[m@Robertson]

From the sound of it, the display is a DZ40.

Is the DZ40 even compatible with the M400? It may not be and instead be meant for the BBSxx mid drives, which it for sure is designed to work with. I would find a display others have used with the M400, buy one of those and plug everything back in and see what happens.

https://www.aliexpress.us/item/3256805348015894.html

Next thing, unfortunately, is start swapping out the cheapest parts to see if the replacement lets the motor start working. You work your way up the ladder in terms of expense.

 

[Kilowatt]

Hi
I am new to this thread as well as ebikes and need some help please.
I am trying to build a plywood e-bike. I have bought a Bafang M400 mid drive motor and from a separate company a battery, display, and cables.
I have connected everything up (battery, speed sensor, display). It is a very cheap display that only shows battery level and power assist level. When I turn it on It shows a full battery and I can increase and decrease the assistance level, but there is absolutely no power from the motor. I have checked and rechecked the connections, how can I diagnose the problem. I have a multi meter but little electronic knowledge.
Thanks for reading and any answers

Aaron, just went through this no power problem. If you have break cutoffs make sure they are connected. It can be your display, speed control, or pas sensor or even controller. I got a new display but no help. Does your display match your controller protocol (UART, etc)? I never fixed mine so replacing the whole system. The China seller only sent the display but said the othe parts are out of stock ??? You will see voltage input at the controller input from battery but any system part can shut down power if bad. Careful poking around with your meter. I was attempting to tap into the light for 48volts into a dc to dc converter and may have caused my problem but that is a done deal.

 

[Kilowatt]

From the sound of it, the display is a DZ40.

Is the DZ40 even compatible with the M400? It may not be and instead be meant for the BBSxx mid drives, which it for sure is designed to work with. I would find a display others have used with the M400, buy one of those and plug everything back in and see what happens.

https://www.aliexpress.us/item/3256805348015894.html

Next thing, unfortunately, is start swapping out the cheapest parts to see if the replacement lets the motor start working. You work your way up the ladder in terms of expense.

Great responses. Trial and error swapping out is the way to go. Oh ya, Aaron, what is a plywood e-bike? Plywood does’t conduct electricity! LoL.

 

[DieselTech]

I believe a plywood bike is a bike that is cut out of multiple pieces of plywood, & then all laminated together using epoxy & fasteners. They look quite nice when done in Baltic Birch plywood.