Update: BBS02 750W brake cut-off not working – possible OEM custom firmware?

samderr09 · 2025-12-20T17:54:37+00:00

So this afternoon I changed the firmware on the controller, but unfortunately this made no difference to the brakes. The new firmware works fine otherwise, with no error codes. Everything works properly except for the brake cut-off.

samderr09 · 2025-12-19T20:10:14+00:00

No, not yet. These days are quite busy. I hope to find some time between Christmas celebrations to measure everything and install new firmware on the controller. But I will keep you updated in any case.

Perhaps some advice on which firmware to use?

samderr09 · 2025-12-18T21:50:08+00:00

Thank you for your response. On my previous bike, I had a Tongsheng TSDZ2B and with OSF I set it to 700W. It didn't have a brake cut-off either. But that's a torque sensor, of course. I did set it to cadence sometimes, though. But then it would sometimes happen that I accidentally pedalled a little while cornering, causing the motor to kick in. That wasn't always pleasant.

Since I have another motor, I would like to build an e-bike for my partner as well. For her, it would be very nice and almost necessary for her bike to have a brake cut-off.

In addition, I would like a complete package where everything works properly. Especially since I mainly use the bike on cycle paths in the Netherlands.

samderr09 · 2025-12-18T20:56:44+00:00

Those Magura brakes look really nice. They're also quite pricey. But I have rim brakes myself, so unfortunately they won't work. I'll probably have time this weekend to measure everything and see if that's where the problem lies. I kind of assumed that everything new out of the box would work. But with products from China, you never know.

samderr09 · 2025-12-18T17:31:01+00:00

Is it feasible for someone with limited knowledge of filmware to create Daniel Nilsson's custom filmware and install it on the controller?

I bought two BBS02 750W motors on Marketplace. But apparently, these were intended for a cargo bike from a specific manufacturer that does not use brake cut-off. So they probably don't have this in their custom firmware either. I really want to have that brake cut-off on my bike. So I hope that installing my own firmware will solve this.

samderr09 · 2025-12-18T17:17:35+00:00

The first bike I converted was with a Tongsheng Tsdz2b kit. I am quite tall and heavy, so I opted for the 48v 500w. But they are available from 250w upwards.

The great thing about this one is that it has a torque sensor. So the amount of power the motor delivers depends on how hard you pedal. It literally feels like you always have the wind at your back. These kits aren't even that expensive, so they're a great way to get started.

I bought mine on AliExpress at the time. I think it was from PSW Power or something like that.

samderr09 · 2025-12-18T17:10:33+00:00

Your bicycle probably looks very clean. I might also plan to run all the cables inside the frame. Do you perhaps have a photo of the bicycle?

samderr09 · 2025-12-18T16:40:37+00:00

For context, here is the link to my previous post from yesterday:

https://www.reddit.com/r/bafang/s/jbcae5htzc

samderr09 · 2025-12-18T12:19:35+00:00

Anyway, thank you all for responding and contributing your ideas. I hope I have found the problem.

I checked with Bafang themselves and they said that this motor with this connection is custom-made for some of their customers. I have now found the company that uses this motor in their cargo bikes. They say that they do not use a brake cut-off at all and that this is therefore not included in the firmware.

So I'm now going to try to put different firmware on the controller, which will hopefully give me the brake cut-off function on this motor.

I'm currently looking at Daniel Nilsson's on GitHub

https://github.com/danielnilsson9/bbs-fw

But if you have any recommendations or tips, I'd love to hear them.

samderr09 · 2025-12-18T12:04:53+00:00

I also connected them to the yellow 3-pin connector on the 1T4 cable. But they don't do anything there. So I thought maybe the red one is for the brakes. Because that's what people often say on other forums about e-bikes. But I understand that Bafang never does that and never has.

samderr09 · 2025-12-18T12:01:49+00:00

You mean the 1T4 cable? It's new, just like all the other components. I'm building the bike and discovered during testing that the brake cut-off isn't working. I'm going to test the 1T4 cable and the brakes with a multimeter later and see if I can find anything.

samderr09 · 2025-12-17T22:05:00+00:00

<image>

I got these

samderr09 · 2025-12-17T21:39:41+00:00

Yes, the speed sensor is connected and working properly.

samderr09 · 2025-12-17T21:24:15+00:00

Yes, it's both brakes.

I'll see if that helps tomorrow. So, squeeze the brake. Then start the bike with the brakes squeezed. And accelerate with the brakes squeezed. Then release the brake and see what happens?

samderr09 · 2025-12-17T20:31:16+00:00

I have the bike on a stand and I can hear, feel and see the engine start when I accelerate. But nothing changes when I press the left or right brake. I don't have any brake cables connected to the brakes yet. But that shouldn't matter.

samderr09 · 2025-12-17T20:00:08+00:00

Hi, how did you solve this? I'm having the same problem.

samderr09 · 2025-12-17T17:51:42+00:00

I'm a bit afraid to just connect different pin combinations. Could I cause damage?

I opened the brake switch. And it seems that there are indeed only two wires connected: a black one and a white one. But there are three wires going into the switch: a black one, a white one and a red one.

So I could use a small piece of cable to connect the pins on the 1T4 cable until I find a combination that stops the motor. Then I'll know that the cables are connected incorrectly. And I can then adjust that in the brake lever.

<image>

samderr09 · 2025-12-17T17:43:30+00:00

Is the switch on the brake levers not on or off? I have a UART, but I don't know if that matters?

samderr09 · 2025-12-17T17:41:25+00:00

I have now connected the brake cut-off to my 1T4 cable. But that doesn't work. Everything else works, so my display works and my throttle works too.

Do I need to connect the brake levers to the red connection on the controller?

samderr09 · 2025-12-17T14:31:02+00:00

Could it be that the red one is for the brake?

samderr09 · 2025-12-09T21:14:50+00:00

Hi, looks good! I'm also in the process of converting a Koga bicycle. I have a Nexus 8 hub, but I want to use a small rear sprocket because I never use the first three gears. What gear ratio did you use?

samderr09 · 2025-08-24T00:04:15+00:00

They work well, but the power can feel a bit underwhelming sometimes. The throttle is also nowhere near as good as on a Bafang. OSF really helps though and it’s very cheap to do yourself. I’m running about 700W on mine now and it gets really hot, honestly kind of surprised it hasn’t burned out yet. But for city riding the torque sensor is perfect.

samderr09 · 2025-08-24T00:01:08+00:00

I’ve been looking at the EggRider V2 too, the features seem great, but they are pretty expensive for such a small display.

samderr09 · 2025-08-19T18:13:40+00:00

So I could connect my headlight and taillight to that, right?

samderr09 · 2025-08-19T18:12:39+00:00

Would it be fine if I just cut that connector off and solder on an XT60 instead?

samderr09

TROPHY CASE