Bafang brake sensor issue

[Toddjamin]

Hi folks

I’m converting an elephant bike (Pashley pronto/mailstar) with a BBS01. It’s nearing completion, with most stuff working as it should, except the brake cutout.

I went for the disc sensors, as the bike has drum brakes, and I wasn’t sure about the pull ratio of the bafang levers. I know they are working, as they trigger the brake light on the light set I’ve installed - a set like this https://www.amazon.co.uk/Ebike-Waterproof-Front-Headlight-Mid-Drive/dp/B09GFTLCY3

The brake sensors do not however, cut out the motor, or light the little warning light on the 500c head unit.

And ideas on why the sensors aren’t doing their job?

Many thanks in advance for your help!

 

[guerney]

BBS01

BBS01 or BBS01B? I have a suspicion things like that are designed for other BBSXXX motors. My BBS01B controller died after I connecting something similar, but it did work briefly once, then my controller became a brick. It didn't work long enough for me to test brake cutoff.

 

[AGS]

Here is the wiring diagram for the BBSHD. You need to check to make sure your BBS01 is the same.

Be careful not to short circuit the 5 volt supply by connecting it to 0 volts through the brake switch otherwise you will blow the voltage regulator in the controller. And that will result in a world of pain.

 

[saneagle]

The cutoff switch shorts a 5v signal wire to ground to change its state from high to low. When the state is high, the controller gives power, and when it's low, power is cut. Which way round have you set your sensors?

 

[Toddjamin]

BBS01 or BBS01B? I have a suspicion things like that are designed for other BBSXXX motors. My BBS01B controller died after I connecting something similar, but it did work briefly once, then my controller became a brick. It didn't work long enough for me to test brake cutoff.

Ah, I’ll check the compatibility again, but the brake sensor problem existed when I tried the system off the bike before I installed the light thing too. I don’t think it is the light causing the issue, I just used that to highlight that it was receiving a signal from the brake sensors, but that the motor wasn’t.
Many thanks!

 

[Toddjamin]

Here is the wiring diagram for the BBSHD. You need to check to make sure your BBS01 is the same.

Be careful not to short circuit the 5 volt supply by connecting it to 0 volts through the brake switch otherwise you will blow the voltage regulator in the controller. And that will result in a world of pain.

View attachment 58280

Thanks for this, I’ll get the multimeter out!

 

[saneagle]

Be careful not to short circuit the 5 volt supply by connecting it to 0 volts through the brake switch otherwise you will blow the voltage regulator in the controller. And that will result in a world of pain.

You won't do any harm shorting the 5v brake signal wire because it's only held high by a resistor. It's not connected to the 5v supply. It's designed to be shorted.

 

[AGS]

A fella over on ES shorted pin 6 to pin 8 on the brake cable and blew the voltage regulator in his controller.

He had brake sensors with 2 pin red plugs and connected them to the yellow brake sockets, thinking it would be ok and boom went the regulator.

 

[saneagle]

A fella over on ES shorted pin 6 to pin 8 on the brake cable and blew the voltage regulator in his controller.

There is no pin 6 and 8 on the brake cable. If you short pin 6 to pin 8 in the main harness, you will blow the 5v regulator, since that 5v comes direct from it. The same will happen if you short the throttle 5v to ground. The brake signal is on pin 4. The 5v in the brake connector and that pin 4 is not a real 5v. It's just a signal voltage through a 10k resistor, so the most current flowing from a short would be 0.5 miliamps. The regulator can provide 500 miliamps all day.

I'm guessing that the guy on ES did a bit of his own wiring without understanding how it works. Have you got a link so I can explain to him?

 

[AGS]

I have no idea what you are talking about.

 

[saneagle]

I have no idea what you are talking about.

View attachment 58284

OK, I see what he did. That's the 5v for a three-wire switch. Shorting it will blow the regulator.

 

[AGS]

Yep that’s why you shouldn’t mix and match red and yellow brake connectors.

The OP just needs to be careful he doesn’t do something daft like that trying to get his brake light to work and the motor to cut off using the same switches.

I use a relay so the motor cut off is isolated from the brake light. And I never run any lights powered directly from the controller. I always use a dc to dc converter for lighting.

 

[Toddjamin]

Yep that’s why you shouldn’t mix and match red and yellow brake connectors.

The OP just needs to be careful he doesn’t do something daft like that trying to get his brake light to work and the motor to cut off using the same switches.

I use a relay so the motor cut off is isolated from the brake light. And I never run any lights powered directly from the controller. I always use a dc to dc converter for lighting.

The brake lights work fine, and I don't really care about them. I just mentioned that as it proves that the sensors work, and it's not a simple "buy a new set".

It's the brake cutout on the motor that isn't working, I want that to work so I can adjust pedals at lights or as I brake. Plus it's a cargo bike for me and my kid, so want the most safe system I can.

 

[guerney]

It's the brake cutout on the motor that isn't working, I want that to work so I can adjust pedals at lights or as I brake. Plus it's a cargo bike for me and my kid, so want the most safe system I can.

If you haven't already, in the meantime you could perhaps set assistance to stop fast when you cease pedalling.





p.s. "Start current" at 10% makes U-turns easier, there's no lurchiness.

 

[Toddjamin]

If you haven't already, in the meantime you could perhaps set assistance to stop fast when you cease pedalling.
p.s. "Start current" at 10% makes U-turns easier, there's no lurchiness.

Great tip, thanks