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Diagnostic software for Bafang

Posted: Mar 20 2021 1:33pm
by -andreas-
Hi all,

I am new here. I put together my own eBike last spring to be able to transport myself a more safe way during Corona. I bought a Bafang 750W mid drive kit. Have worked pretty well, but have had some problems that I have solved.
Now I have a new problem. The display turns on, but no sound or anything from the motor. I disconnected most things and when disconnecting the speed-sensor from the rear wheel it, it started working again! I had a spare, so I changed to that. But when later trying the bike it had the same problem again. Tried and tried. Disconnected speed sensor again, all brake sensors and throttle, but nothing. Then suddenly it worked again. But when I stopped it was the same problem again. Tried several times, then it worked again, but as soon as I stopped, it again took several attempts to work again.
Now I am thinking that maybe it is some moisture in the cables or something that makes it believe that the brake is activated? I had a serial cable that I had not used before, and connected that to my PC and downloaded the Bafang Configuration Tool. I had hoped that it would show the status of the ebrake. But it does not. Is there any diagnostic software that can show this? I know some displays can show this, so the controller should be able to tell the computer.

Re: Diagnostic software for Bafang

Posted: Mar 20 2021 1:50pm
by fechter
Which display are you using? On my display, there is a little brake symbol that comes on when the brakes are activated.
There are a number of faults that will cause the motor to not run. Most of them will trigger an error code on the display. If the brake wires are disconnected I don't think a little moisture would be enough to make the controller think they are on. The speed sensor doesn't need to be attached to make it run for a few seconds. If no signal from the speed sensor, the display will turn off after a given time. If the speed sensor is blinking when the wheel magnet passes by, the sensor is good.

Try disconnecting the main display cable connector and inspect the pins and socket. Also inspect all the cables for damage, like pinched spots. Also try disconnecting the throttle if you have one.

Re: Diagnostic software for Bafang

Posted: Mar 20 2021 5:52pm
by -andreas-
Thanks for your quick answer!
I have SW102, so no ebrake symbol. Is there any software otherwise that can act as a display with ebrake symbol and all?
Ok, thanks for info, no maybe moisture is not enough for those kind of sensors. The throttle though seems to be able to get pretty unstable when it has been used during different weather-conditions, but that is another problem that I had before.
Yes, I have disconnected the throttle.
I have also noticed that if the speed sensor does not work it takes a while before the whole thing turns off, but that is like 10 minutes or something, so it is not that. Now the display also is on when the motor is not working.
Why I suspected some kind of moisture problem is that the problem is intermittent. Most of the time the motor does not work, but sometime it does. It could of course also be a cable that have a partly broke wire or a connector that does have some irritated pins. But it seems pretty likely that it is somehow detecting brake.
I have checked the cables. Before I switched the speed sensor I switched the main cable harness and also the display (for another sw120), but that did not change a thing. But maybe the cable to the motor. It looked ok though.

Re: Diagnostic software for Bafang

Posted: Mar 20 2021 8:02pm
by fechter
Most common faults will generate an error on the display. Strange yours shows no faults but doesn't run. It could be the brake line, but since you already changed the main harness it would have to be in the part between the motor and the first connector.

I would try disconnecting the battery and pulling off the controller side of the motor and just look inside where the controller is. Also good to try disconnecting and reconnecting all the plugs inside there. Look for signs of water ingress. Water on the controller board could do all sorts of things. Note: after disconnecting the battery, there will still be pack voltage on the controller caps. You can hold the power button until it tries to turn on to discharge them.

I'm not aware of any diagnostic software other than what's built in to the display. The programming interface doesn't give any real time data.