A Desperate Bafang E-bike rider from Germany urgently needs your help!

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stesie1001

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Hello,
I urgently need your help! I'm from Germany, unfortunately there aren't many e-bikes with Bafang motors in Germany! If there are problems with the electronics, like with my e-bike, you won't find a workshop that can help you! I bought a rear wheel with Bafang hub motor, controller, battery, wiring harness and display from Alibaba, all as a complete set! UART protocol! After installing it, I drove happily for 70 km without any problems, until the motor suddenly stopped! An error message came up with overvoltage protection! At the time I was traveling at about 15 mph, without thumb throttle! Because I thought the controller had been damaged, I ordered a new one and installed it! But the same problem! The display starts up normally, but when I then move the thumb throttle or pedals, the error message comes up immediately, overvoltage protection! I bought the Besst Tool from Bafang! Connects to the display, which is also read! If the battery or the controller is then to be read, it says that no connection is possible! I hope you can help me!? Many thanks for your support! Greetings from Germany Stefan
As my English is not the best, I asked Uncle Google for help!
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First, thank you very much for your help! I've taken everything out of the bike and have the individual parts in my room! I have a multimeter! Where should I measure?
 
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I have a number of Bafang G020's and use them daily. They also are 48v 500w units just like yours.

First of all, the BESST tool is worthless, I am afraid. BESST is made for Bafang CAN bus mid drive motors and you don't have one of those.

The motor is just a dumb motor it has no idea what voltage its supposed to be receiving. It takes whatever the controller and display decide to give it... so my first culprit to investigate would be the controller. Since you have already tried replacing that, my next culprit would be the display. Your display is a DPC18 which should be fine for a 48v system... but Bafang resellers often use firmware unique to their product order so we can't say for sure.

But... what if the error message is factual? What if the battery is overcharged? @Annieolnie has touched on this issue as well. You want to test the battery and ensure it is not charged to anything higher than 54.6v. Hopefully its a fair bit less than that as you don't want a battery sitting at that 100% charge level.

You measure the battery terminals on the battery to see what voltage it is outputting. Also, if the DPC18 has a numeric voltage display, look to see what it says. Report what you see back to us please.

Myself personally, I always use KT controllers and displays. They are known quality parts and there are never any configuration surprises. I just installed a KT T12S 48v, 30a controller - which is quite powerful once you let it ramp up its power (I have mine set to slow-start so it never stresses the bike frame or induces any sort of controllability issue). My G020.500's are set up like this:

  • KT T12S controller, purchased with the 1T4 control cable. This one uses the HIGO/Julet plugs, and not junky JST connectors
    https://www.topbikekit.com/t12s-36v...er-with-julet-waterproof-connector-p-733.html
  • KT-LCD4 display. You can buy one cheap via the link above. This is a US$21 display and it is as small as an EggRider v2, but just as feature-rich as the much larger and very common KT-LCD3.
  • Wuxing 300x throttle. By far the best out there. If you can't get a 300x, a 130X is available at the above link and it is again very cheap.
  • I use the 8PAS PAS sensor sold at that same link. I'd use a 12-magnet system but the bigger PAS magnet ring will not fit on my bikes.
One thing about KT controllers: They use a 'simulated torque assist' algorithm that gives a completely different, and superior experience from most cadence assist systems. PAS response is not an on/off switch, it ramps up gently, ramps down at high cadence cruise, ramps back up again if you start climbing a hill and ramps down when you reach the summit.

If you decide to go the KT route I am describing above, all of the settings for the controller are in the link below. Scroll down to the section entitled "Front Motor Settings". You can duplicate all of them as you have the exact same motor I do except for one: The C1 setting should be set to 00. And if you need a controller manual post here. I have a copy written for a native English speaker, which will be a lot easier for you to translate than the ones translated from Chinese by a Chinese speaker with a poor grasp of English.

https://talesontwowheels.com/2023/0...uler-back-to-front-part-4/#FrontMotorSettings
 
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Well, you need to start by finding out what charge your battery has. Is it over charging? When you said you had gone 30 km, was it that day or with the new bike altogether? You can also check your charger to see what output it is giving. Did the error message have a specific number? There are several different roads to go down here, let's start at the beginning. As I'm writing this m@Robertson has shown up and he knows far more then I do, so I will just add this on and we can go from there.
 
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Hey there, you absolutely need a voltage reading from your battery. I'm worried your battery's BMS may have lost a connection and cannot regulate itself when charged. You need to sort this out first.This, in the least, could kill your battery and in the worst case could cause it to melt down if it continues to over charge. Let's just start by keeping you safe.
 
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OK, good. I just don't like forum members starting forest fires. You can also check the battery's seating bracket that goes on the bike to see if any of the connectors had a short, after that you can keep going with m@Robertson. He knows his stuff. Best of luck to you.
 
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No, everything is OK! No broken cables! There is a thin rubber mat between the battery and the frame!Since my e-bike is in the house, I would burn down my house! That's just as bad as burning down the forest!
 
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ok that is very wonky!
someone that knows this display will be able to help better than me.

Almost seems like some type of short somewhere.... to me..
 
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Yes, error 08 is usually a hall sensor, which would be odd with a new motor.Error 30 is a communication error that could be from a pinched wire, which then might explain error 08. If you are up to it, you might want to try some continuity testing to make sure all the connections are good now. I will look into why there is no battery data.
 
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So, according to EBR, the bms on the battery has not downloaded the communications agreement with your display, so it cannot bring up battery data. The new parts you have ordered may fix that. You can check with M@. to see if that is true.
 
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Maybe a new wiring harness makes more sense than reinventing the wheel here. As @Annieolnie has pointed out, you have errors that could be pointing to bad wiring. A 52.3v value with an overvoltage alert makes no sense unless, as @HumanPerson points out, is because the display is set to 36v... but your display was working fine for a few weeks so thats mighty unlikely.

The wiring harness would be like a 1-to-4 cable, where one wire comes out of the controller and branches out to 4 more connections that go to the brakes, throttle etc.
 
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So, according to some people with dpc18 displays you can't change the voltage setting without having the battery coms. This would mean you are currently stuck on whatever the factory settings for your display might be. So, this would explain alot if you are stuck on 36 volts, as humanperson mentioned. Jeez, live and learn.
 
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