PSA: How a faulty third-party display burned my Bafang Ultra M620/G510, and then my BBS02

nimpol

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TL/DR:

If your bike shut off during ride and display went black, you might have burned both your controller and display. Then, if you replace the controller/motor and plug in the same old display, that new controller will be burned immediately.

You can test your display before reusing it, though.

Post:

I have found a similar problem on forums in just three cases:
Bafang ultra m620 controller burnt
Bafang Ultra G510 - error code 11 & burnt controller
M620/G510 burnt controller issues

People there burned two-three motors in a row before seemingly giving up on electric transport entirely. That’s sad, so I hope this experience will help someone.

This happens with the M620 and third-party displays (Eggrider in posts and 500C in my case).

I have not found confirmed cases with other motors or stock DP C18 displays. That makes me think that though the UART M620 works with any UART display, it may be a bad idea to use it. If someone shares the same issue with the stock DP C18, well, then it doesn’t matter what you use and you just hope for the best.

Before, I had a 48v BBS02 with a Luna Mini 500C display. When I switched to a 52v M620, I hated DP C18 from the first sight and bought some version of the 500C from eBay.

For about 700 miles, everything was fine, then I suddenly lost power during a ride, and the display went black. I took apart the motor to see the same burn damage as in the first post above.

Also, my bike has two batteries with a diode balancer, as my previous BBS02 setup had. This might be the cause too, but I never had any problems with this before. Though, Eggrider does not advice to use their displays with two batteries setup.

I ordered a new motor and a replacement controller to fix the burned one and have a spare. Normally, I would just replace the motor and see if it works. Luckily, the posts above gave me the idea that something is wrong with the display. So, I took one of my very old BBS02s and immediately burned it with that 500C just by plugging the green connector into the motor. Darn. I might have sold it, but it’s much better than burning a new M620.

I tested the 500C with a multimeter, and it surely shorted between “P+” and “Ground” - zero ohms. A working display shows some resistance, and that resistance changes when pressing the power button. Then I tested that working display with the motor again, just in case, to see if testing itself could damage it. And it’s fine.
 
Yeah. Weird problems
I just caught another one on a battery. A bms error that' almost impossibly to spot without testing but now I know.

BMS turns hot on the balance resistors when it shouldn't and drains cells. Spot it by feeling, with a thermometer or a temperature camera.
 
At least you can buy a BBS02 controller. DIY oriented systems FTW.
 
Interesting and insightful, Nimpol, it seems you've encountered and documented and then followed up with research a new and expensive 'burn' and now another troubleshooter leffex writes about sensing display related errors as he feels a battery pack of all things how original and attentive to detail !
 
I heard about this problem once but I can't verify or remember clearly.

We have had some people trying to connect a bafang "electric bike kit" display to a propriary system of a m500 motor or Shimano as they are branden (Bafang motor + shimano battery). In those instances a male-to-male green 6-pin connector won't cut it. One have to splice and connect the correct wires if one wishes to use such a display and it should work after correct installation at least in theory

Other than that the correlation of bricking a motor because of a display is low however it is possibly to my knowledge. The reason is that some displays receive battery power. If that lead gets shorted to the communication or whatever it may be the reason and the cause of this fenomenon. Also light lead might also go via the display and then it is the same if the light uses battery power voltage.

Tongsheng firmware display won't kill a bafang motor or vice versa to my knowledge. It's good to get the correct firmware though or things won't work as they should.
 
TL/DR:

If your bike shut off during ride and display went black, you might have burned both your controller and display. Then, if you replace the controller/motor and plug in the same old display, that new controller will be burned immediately.

You can test your display before reusing it, though.

Post:

I have found a similar problem on forums in just three cases:
Bafang ultra m620 controller burnt
Bafang Ultra G510 - error code 11 & burnt controller
M620/G510 burnt controller issues

People there burned two-three motors in a row before seemingly giving up on electric transport entirely. That’s sad, so I hope this experience will help someone.

This happens with the M620 and third-party displays (Eggrider in posts and 500C in my case).

I have not found confirmed cases with other motors or stock DP C18 displays. That makes me think that though the UART M620 works with any UART display, it may be a bad idea to use it. If someone shares the same issue with the stock DP C18, well, then it doesn’t matter what you use and you just hope for the best.

Before, I had a 48v BBS02 with a Luna Mini 500C display. When I switched to a 52v M620, I hated DP C18 from the first sight and bought some version of the 500C from eBay.

For about 700 miles, everything was fine, then I suddenly lost power during a ride, and the display went black. I took apart the motor to see the same burn damage as in the first post above.

Also, my bike has two batteries with a diode balancer, as my previous BBS02 setup had. This might be the cause too, but I never had any problems with this before. Though, Eggrider does not advice to use their displays with two batteries setup.

I ordered a new motor and a replacement controller to fix the burned one and have a spare. Normally, I would just replace the motor and see if it works. Luckily, the posts above gave me the idea that something is wrong with the display. So, I took one of my very old BBS02s and immediately burned it with that 500C just by plugging the green connector into the motor. Darn. I might have sold it, but it’s much better than burning a new M620.

I tested the 500C with a multimeter, and it surely shorted between “P+” and “Ground” - zero ohms. A working display shows some resistance, and that resistance changes when pressing the power button. Then I tested that working display with the motor again, just in case, to see if testing itself could damage it. And it’s fine.
I have the M620 on my bike as well and its been fine for over 1500 miles and then one day the stock display ( DPC-18 ) went black for some unknown reason and I was on 2 battery system with the Microchip balancer at the time .

I did all the tests and came out to be that the display just went bad and I plugged in my backup display ( DPC 14 ) and everything worked just fine for about another 500 miles and that went black as well then today I had tested another backup display (BL-18 ) I have which I use on my other BBSHD bikes which work perfectly fine with this Generic Bafang compatible display and it also worked on the Ultra M620 for about another 300 miles and then kept on giving me the ERROR 30 code which is a communication issue as to what I could find out about this error. The bike still worked just fine the only thing that stopped working on the Ultra was it displaying the speed everything else worked perfectly fine it just displays the ERROR 30 at the bottom of the display is all but the bike still works.
I then tool the ( BL-18 ) display that shows the ERROR 30 code on it when hooked to the Ultra M620 motor and connected it to one of my BBSHD motors and it still worked just fine but still displayed the ERROR 30 code and that kind of tells me the display got a voltage spike of some kind from the Ultra M620 controller and it must have caused the error on the display and took out part of the display that measures your speed because that is the only thing that does NOT work on the ( BL-18 display ).

The other 2 Original BAFANG displays ( DPC-18, DPC-14 ) are completely JUNK I tried the 2 original Bafang displays on my other BBSHD bikes and they are COMPLETELY DEAD. I can not find any burnt marks on the boards when I took the displays apart.

If I leave the bike as is with the ????? controller on it and the ( BL-18 ) display the bike works just fine but NO speed display reading everything else works.

Should I change out the motor since I do have a spare motor to try r just leave it as is because if I really need to see how fast I am going I can google maps my phone or use the SPEEED android app on my phone to display my speed. ???

Luckily I have a spare Ultra M620 to install on the bike and see if it still takes out displays for some unknown reason.
 

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