Bafang BBS02 Throttle/PAS Simple Fix

[Rassy]

Richard, as to your above post, I can't help. Are you already using the smallest chain ring you can find on the Bafang?

And I did a few tests using throttle vs level 9 PAS and both gave identical top speed. There was a slight loss in speed when switching from one mode to the other, I think mostly because of my controller settings. In all cases there was no pedal input because I could not find a hill that let me keep up with the pedals at full throttle or PAS 9.

 

[rstanley]

High Rassy,
Here is a bit more detail about throttle vs pedal control on the BBS02 motor. It was gleaned from the tech at our DOST supplier, Steven Dupret. (He is an excellent resource for all you fellow Dosters out there...)

IN ~ 2017 Bfang made the decision to drop throttle dominance over the pedal assist due likely to growing legislation restricting e bikes by whomever...That change was made in the circutry of the controller itself. It cannot be changed by the programming cable settings.

My issue is less about top speed as i is with the ability oto climb up a steep neighborhood hill a steep hill (~20% grade with a street incline length of .5 km). I have to pedal like heck, even with use of the 34 tooth ring of my rear cassette, the motor grinds down to a near stall. My solution is to simply gear it down by swapping out the 34 tooth rear large cassette ring with a 40 or greater tooth ring. This may also involve adding extensions for the rear derailleur and possible chain lengthening by a few links.
Normal cruising speed will not be affected but its climbing ability should be enhanced by ≥20+% depending on functionality of ring size I wind up with.
The cassette is a Shimano GH cassette with a spline for attachment of of chainrings.

Just a heads up

Richard / Ashland

 

[tomjasz]

It can be changed by flashing the firmware. It not circuitry or hardware.

 

[rstanley]

Tom if so tell us exactly how. My source is a seasoned ebike tech who said it couldnt be changed . Id love to see what you recommend specifically. Thanks

 

[tomjasz]

It will take some digging but here is a start for you.
https://www.endless-sphere.com/forums/viewtopic.php?f=28&t=100064

This lays out the procedure. I asked to remain anonymous when I share this as we were worried about a negative reaction from Bafang. But when Doug sold California eBike, I also retired with him after doing support for his customers for 6 years. Unfortunately, I copied all my support files and notes over to a new computer and apparently lost some of the files. But there are BBS02 firmware files out there in the wild. There are several posts here on ES, some searching and due diligence ought to find them.

If your source is well connected he should be able to get the .bin files.

See also, https://endless-sphere.com/forums/viewtopic.php?t=93977

 

[dweebur2]

I've done two of them. On one of them there was the shifter cut off, or whatever it's called, which I have found as worthless, so I just cut it off within the controller cavity and protected the wires so they wouldn't short, and used the hole in the gasket to run my new wires out. In the other I made a little channel in the rubber, just under the metal piece, and ran the wire through the channel so when the metal piece was replaced the wire was held tightly. In either case you can add liquid tape or whatever to seal the controller cavity up.

Update:. I successfully did it! Much nicer to choose between pas and throttle in a push of a button. I just used very thin wiring. Tried to cut out a slight channel however that rubber is stronger than it looks! Between the rubber wire harness and the gasket the wire smoosh in there nicely. Thanks again for all the advice.

 

[Rassy]

It's always nice to hear when something works out okay. I also like that it just takes one quick push on your switch of choice to disable PAS when you need to just pedal slowly through a congested area.

So in some ways I feel having my handy rocker switch is an improvement over the pre 2017 versions of the BBS02.

I am no longer interested in doing either an electronic fix or a complex flashing of the controller, which I tried to do a couple of years ago and was unsuccessful.

 

[tomjasz]

 

[LewTwo]

So right, wrong, or indifferent here is what I did:

First I cut the small grey PAS wire in half. This wire is in the controller cavity and is one of the four wires attached to the small connector. Do not confuse it with the grey wire attached to the five wire small connector which also includes a blue wire.

... Everything worked as expected, namely when the switch was closed the BBS02 worked the same way as when it was delivered. And when the switch was open the PAS was turned off and the throttle worked properly in all PAS levels whether you also pedaled or not.

I have been looking for a good photo of the BBS02B controller wires so that I could understand exactly what wire it was that you cut. I think that I found one at:
https://ebikelettrica.com/en/prodotto/centralina-bafang-bbs02b-25a-36v/

If I have read correctly then the wire that is cut is the grey one indicated by the blue arrow in this image:

Further if one just cuts this wire then PAS would be disabled and the BBS02B would operate in "Throttle Only" mode... end of story.

 

[danielnilsson9]

So right, wrong, or indifferent here is what I did:

First I cut the small grey PAS wire in half. This wire is in the controller cavity and is one of the four wires attached to the small connector. Do not confuse it with the grey wire attached to the five wire small connector which also includes a blue wire.

... Everything worked as expected, namely when the switch was closed the BBS02 worked the same way as when it was delivered. And when the switch was open the PAS was turned off and the throttle worked properly in all PAS levels whether you also pedaled or not.

I have been looking for a good photo of the BBS02B controller wires so that I could understand exactly what wire it was that you cut. I think that I found one at:
https://ebikelettrica.com/en/prodotto/centralina-bafang-bbs02b-25a-36v/

If I have read correctly then the wire that is cut is the grey one indicated by the blue arrow in this image:
BBS02B controller Wires (cut here).jpg
Further if one just cuts this wire then PAS would be disabled and the BBS02B would operate in "Throttle Only" mode... end of story.

If you just want to disable the PAS sensor, just unplug the connector, you don't have to cut the wire, all 4 wired on the connector is for the pas sensor.
Red -> 5V
Black -> GND
Grey -> PAS1
White -> PAS2

There are two offsetted pulse signal to make it possible to determine pedal rotation direction.

Anyway, for anyone wishing to take a software method BBS02B is now supported in the open source firmware version:
https://github.com/danielnilsson9/bbs-fw

There is smooth throttle/PAS override.

 

[Rassy]

Thank you, Daniel. I see this as a great step forward. I will be interested in results others get.

One of my trikes is now getting the Error 21. At first, I expected just a magnet or speedometer pick-up problem, but initial tests have led me to believe the problem is in the controller. Even though the PAS sense wire has been severed and a handlebar rocker switch installed, I will install this software on this controller in the near future. Everything except for the speedometer issue is still working properly.

 

[LewTwo]

If you just want to disable the PAS sensor, just unplug the connector, you don't have to cut the wire, all 4 wired on the connector is for the pas sensor.
Red -> 5V
Black -> GND
Grey -> PAS1
White -> PAS2

There are two offsetted pulse signal to make it possible to determine pedal rotation direction.

Thank thee :thumb: :thumb: :thumb:

 

[dweebur2]

I will try this as well. If this fixes the dreaded throttle/pas issue I will buy you a case of beer Can you use the speeed app to make basic changes after using the configuration tool or do you always have to use the alternate configuration tool?

 

[rstanley]

Rassy, Hello again.
Well given the discussion around reprogramming the controller to get the throttle to dominate the PAS, which is likely to interfere with the display and risks voiding my warranty, I am reverting to a simpler fix: changing the rear cassette to include a 40 or 42 tooth ring in the existing 9 chain ring cassette--with its current largest ring of 34 teeth.

My issue was not more top speed but more climbing power. You had suggested a smaller front chain ring at the pedals and that would be far simpler; However, there is no room for reduced internal diameter of such a ring as the existing ring is offset and at that it barely clears the motor housing as it is. Hence my focus on increasing the diameter of the largest ring of the rear cassette.
Its on order and I will hopefully be installing it--along with the longer reach derailleur and the few necessary added chain links, next week. Will revert after a few tests.
Richard

 

[Rassy]

Richard, I have sent you a phone message about adapters for smaller chain rings on a Bafang BBS02. I think this is also covered somewhere in the forum, but no idea where. Seems like there is also an issue with chain alignment, which would not be a problem with a recumbent bike.

 

[amberwolf]

maybe

https://endless-sphere.com/forums/viewtopic.php?t=75553

https://endless-sphere.com/forums/viewtopic.php?t=50104&start=2275

https://endless-sphere.com/forums/viewtopic.php?t=60773

https://endless-sphere.com/forums/viewtopic.php?t=107741

 

[rstanley]

Hi Rassy,
I received your two views of the 48 t chainring for the BB S02.
I sent you a few oblique views of my existing offset chainring which just clears the a build out section on the cowling for the motor. I will pull off the chain guard for a better view of the build out section on my motor which I think would prevent the use of a smaller chainring ----soon.
Thanks

 

[Rassy]

Richard, small correction, those pictures I sent to you are of a 44 tooth chain ring.

 

[rstanley]

High Rassy , from Ashland
Well, Its been a while but heres an update: I have given up on trying to change the motor power limiter electronically and instead went for another option to get the power for climbing the hills around here.

I purchased a longer throw derailleur and a new rear cassette which spans 11 to 42 tooth chainrings. (Source: https://www.s-ridebike.com)

My original rear cassette was 11-34. That added 25% odd gearing reduction offers the power needed (any larger a rear ring would most likely result in unwanted wheelies !

Highly recommended solution for anyone with a mid drive struggling on serious climbs !
Hope all is well with you !

Richard Stanley

 

[tomjasz]

you will be able to make programming changes to detune the 02B. Typical users try to squeeze more speed out.

Yeah, I just read thru all 9 pages (so far) on the custom BBS02/BBSHD firmware, Near the end, was verification from two users that the PAS/throttle override issue has been fixed.

I just installed a new BBS02B, and haven't tested it much. I did see that throttle didn't work when I was buzzing around in PAS 1, unless I quit pedalling. Then it came on, but in PAS 1, the default throttle is weaker..I could see this a big problem in PAS 9. Damn bike is too powerful for this old geezer and it's going to an novice ebiker. I put it on a similar bike. 26" wheels, 14-34 rear freewheel, as my current BBS02B, but the new motor seems a lot stronger, Pulls to 22 mph in casual pedalling in PAS 2? WTH.

I'm not doing the circuit fix. When I get the program cable, will see if I can detune the bike so the new user will stay out of trouble., If not. then I may have to go the FW route,