Need advice on an alternative controller for Bafang BBS01

[Jan_Niek]

Hi all,

My Bafang BBS01 controller is broken. I could slot in a new controller of the same type to make it easy, but I like going cheap and making it more of a fun challenge. I also need a new display, so whatever I end up buying I can buy as a pair.

Can I just replace it with any cheap controller? I Know how to plug in the motor phase cables, and I believe I know how to match the hall sensor cables' colours, but the bbs01 comes with a 4-pin PAS. Can I use one of the two data pins and plug that into a cheap controller, or do I need a whole new PAS system if I want to use a non-Bafang controller?

Also, a lot of the cheaper controllers don't come with plugs for a speed sensor. It is a geared bike, so the hall sensors won't accurately measure my speed as far as i know. Should I buy a controller with a speed sensor plug OR can I use the 6th pin on the hall sensor line (white cable) on a cheap controller, and plug that into my speed sensor (with power and ground)? So my original bafang speed sensor plugged into (spliced into) the hall sensor cable of a cheap controller and make that report the right speed on my display, is that possible? Or should I go a tiny bit less cheap and just get a controller that actually comes with support for a speed sensor?

Thanks in advance for any advice on the matter!

 

[hillslayer@]

Easiest just get a controller that only needs phase wires speedometer doesn't need the controller

 

[Jan_Niek]

Easiest just get a controller that only needs phase wires speedometer doesn't need the controller

Sorry, I didn't mention this clearly. I want to be able to limit the speed on my E-Bike, for this, I assume I need a way to accurate measure the speed of the wheels (not the motor) and need to use a controller and display to set a max speed, right?

 

[stancecoke]

I want to be able to limit the speed on my E-Bike

There was a S06SC (Kunteng) for central motors in former times, but the item is not longer available at BMSBattery.

The one I am using now is here: https://bmsbattery.com/ebike-kit/695-s06sc-sine-wave-controller-for-central-motor-ebike-kit.html

I only have nice things to say about how smooth it delivers the power. The only problem I have with it is that I spin too fast naturally and get back EMF at the most stupid moments, my problem not the controllers fault hence my move to 12S 44.4v.

https://www.pedelecs.co.uk/topic/30588-bafang-mid-drive-250w-or-higher/

I think you have to go with an open source firmware to achieve this feature with cheap hardware...

 

[ChapinB]

I havent had the controller apart, but Id imagine any controller would function... but may not work the same.
Part of the bafang system is now it works together. The way the pas works, how it interfaces with the screen, the ability to easily add accessories, change settings by screen or usb. Im a cheap skate myself, but would not hesitate to replace with oem in this case.

 

[Jan_Niek]

There was a S06SC (Kunteng) for central motors in former times, but the item is not longer available at BMSBattery.

https://www.pedelecs.co.uk/topic/30588-bafang-mid-drive-250w-or-higher/

I think you have to go with an open source firmware to achieve this feature with cheap hardware...

But doesn't every display which reads a speed also have an option to limit the bike to not going beyond that speed?

 

[ChapinB]

But doesn't every display which reads a speed also have an option to limit the bike to not going beyond that speed?

Not necessarily, take a typical vesc. You can put mph on your screen/phone. But its a calculated value based on gearing and tires. Change gears and it no longer is accurate.
But it does know motor rpm and max motor rpm can be limited.

Iv had other generic systems that show mph too, but its also a calculated value. They know rpm of whatever gear/wheel/doohicky you put the sensor on and you set the multiplier till mph reads correct. These did not have any limiting function that I know of.

 

[stancecoke]

But doesn't every display which reads a speed also have an option to limit the bike

Most hubmotor controllers limit the speed by the electrical revolutions of the rotor. Therefore you have to set the right number of pole pairs and mechanical gear ratio in the display.
The external speed sensor is used only to show the right speed in the display, if the motor is not running on a geared hub motor with freewheel.

Maybe a "Brainpower" controller limits the speed by the external speed sensor, but it is quite random, which firmware version you get, it is possible, that it behaves completely different than expected...

 

[fechter]

What's wrong with your original controller?
It may be possible to fix or the problem might actually by elsewhere, like the display or wiring.

 

[Jan_Niek]

Most hubmotor controllers limit the speed by the electrical revolutions of the rotor. Therefore you have to set the right number of pole pairs and mechanical gear ratio in the display.
The external speed sensor is used only to show the right speed in the display, if the motor is not running on a geared hub motor with freewheel.

Maybe a "Brainpower" controller limits the speed by the external speed sensor, but it is quite random, which firmware version you get, it is possible, that it behaves completely different than expected...

I have a Bafang BBS01, which is bottom bracket system mounted, middrive. How do the Bafang make themselves street legal in the Netherlands where the speed limit for e-bikes is 25km/h? I assume the speed sensor, since there are seven gears between the motor and the wheel

 

[ChapinB]

Bafang system has a rpm sensor that you put on the wheel. Tell the screen what size tire you have, and viola, it knows speed. Speed can be limited, I think - been awhile since Iv been in software.
Otherwise if you limit watts, speed is more or less limited.

 

[Jan_Niek]

Bafang system has a rpm sensor that you put on the wheel. Tell the screen what size tire you have, and viola, it knows speed. Speed can be limited, I think - been awhile since Iv been in software.
Otherwise if you limit watts, speed is more or less limited.

Can such a speed limit be set on a KT controller and display for example?
Also, I originally asked if a 4 and 3 pin PAS are somewhat compatible somehow and I asked if the speed sensor cable 6th pin as an input for an external speed sensor (and then configure it accordingly on the display). I would still like to know if anyone knows the answers =)

 

[stancecoke]

Can such a speed limit be set on a KT controller and display for example?

No, as the Kunteng uses the rotor speed to cut the power, not the wheel speed. It's simply a matter of the firmware, if the external wheel speed sensor is used or the rotor speed...

I asked if the speed sensor cable 6th pin as an input for an external speed sensor

?! the BBS01 UART speed sensor has only 3 pins and the CAN version 4 pins?!

 

[Jan_Niek]

No, as the Kunteng uses the rotor speed to cut the power, not the wheel speed. It's simply a matter of the firmware, if the external wheel speed sensor is used or the rotor speed...


?! the BBS01 UART speed sensor has only 3 pins and the CAN version 4 pins?!

Sorry for perhaps being so unclear, I tried asking if I can plug an external speed sensor, like the ones you pictured, into the white cable of the 6 pin hall connector and then fiddle with the settings on the display to get a good accurate speed reading.

So, if I understand you correctly, even controllers that have a way to plug an external speed sensor into them may not have speed-limiter capabilities? Like the one in the second attached picture?

Picture 1, example of 6 pin hall.

Picture 2, wiring diagram of a KT TO6S

 

[Jan_Niek]

And I'd still like to know (perhaps most of all) if a 4 pin pas system (like in a bafang) can be plugged into a 3 pin PAS on a controller (like a kt controller). Is that possible?

 

[E-HP]

You have a few options, but probably not “cheap”. I’m cheap, but I’ll pay money for quality, or things I can continue to use as I upgrade.

It will be difficult to find a cheap controller with a speed sensor input. Some models of KT controllers have a speed sensor input, and speed can be limited to 25kph when paired with certain KT displays. The default limit is 25kph when using the lcd3, for instance. See page 17. Not sure if that’s a cheap enough option for you, but getting it to work with the stock pas is something you’d need to research. In any case, an external pas would be an option.

https://download.elecycles.com/manual/Display-Manual/LCD3-display.pdf

Another option would be to get the cheapest sensored controller you can find, and pair it with a Cycle Analyst. The CA can accept an external speed sensor, can limit speed to whatever you want, as well as changing the pas behavior (since it uses a closed loop) to use a smoother power based assist (actually similar to the KT’s power assist control mode setting, when set to imitation torque control. But the CA can also adjust assist based on cadence (more or less assist based on pedaling speed) which is a nice feature, at least for me. Plus, you can set power limit precisely. KT can also adjust power/current with about a half dozen options, which may or may not be an issue for you since you’ve been focusing on speed.

The member that I believe has the most knowledge about KT equipment is not on this thread, but you could probably search the forum for models that have an external speed sensor input. If you like a nice looking display, then go with the KT and choose one that you like. The CA is old and dated looking, but there’s nothing available like it, and for me, if I fry my controller, I can just replace it with another dumb controller and all the functionality programmed into the CA, it’s just a quick swap without settings to mess with. It also has user defined modes so I can easily switch to fully unlimited, or a couple of limited modes by toggling the buttons.

I swore I’d never build another bike without a CA, but I did, with my TSDZ8. Unfortunately the CA would not be able to fix the Tsdz8, since it has the worst implementation of a throttle known to mankind, and the CA can’t fix the type of delayed response it suffers from.