BBS02 programming question

[rocketman58]

I am thinking of converting from a Bafang geared hub drive to a Bafang BBS02. My geared hub drive uses a KT controller that has 5 PAS settings. Each setting provides a set level of assist up to the maximum speed of the motor.

This is very different from the original Bafang controller that came with the motor. That controller provided a specific amount of assist up to a certain speed then the assist stopped. For example: Level 1 assist stopped at 9mph, Level 2 assist stopped at 12mph, Level 3 assist stopped at 15mph, etc. It was not possible to pedal at 17mph with a lower amount of assist like you might get in levels 1 or 2.

How does the BBS02 provide assist? Is it like the original Bafang controller I had that limits you to a certain speed in each PAS level? Can I program it so there is no speed cut off at any assist level like my current KT controller?

Currently I ride at speeds up to 20mph using assist levels 1 or 2. I do not (yet) need the level os assist that 3 - 5 provide.

One more question: Are there any issues when using the BBS02 with a 20" drive wheel?

 

[docw009]

My last BBS02B kit was delivered mis-programmed like your bafang hub motor controller, It had 9 PAS levels, with the level 1 set around 10 mph, level 2 at 13 mph, etc , Pretty much unrideable in the lower pAS levels with the assist unexpectedly going away as you approached the speed limit.

Fortunately these are factory settings that can be easily changed. You can buy a $12-18 interface cable on amazon and use either a PC or android phone to access the settings. I've used the PC. Then you can adjust the current percentage for a PAS level and also the speed. Solves the above issue if you raise the speed limit, Here's an example of the screen, There's a coup;e of other screens, I didn't use them, that control how fast current ramps up, etc. Plenty of discussion on the internet too, as to how to use them.

 

[rocketman58]

My last BBS02B kit was delivered mis-programmed like your bafang hub motor controller, It had 9 PAS levels, with the level 1 set around 10 mph, level 2 at 13 mph, etc , Pretty much unrideable in the lower pAS levels with the assist unexpectedly going away as you approached the speed limit.

Fortunately these are factory settings that can be easily changed. You can buy a $12-18 interface cable on amazon and use either a PC or android phone to access the settings. I've used the PC. Then you can adjust the current percentage for a PAS level and also the speed. Solves the above issue if you raise the speed limit, Here's an example of the screen, There's a coup;e of other screens, I didn't use them, that control how fast current ramps up, etc. Plenty of discussion on the internet too, as to how to use them.

View attachment 353216

So I can set the speed limit to 100 in each PAS level, and increased the assist level for each PAS level? Would this allow me to travel at maximum speed no matter which PAS level I select? For instance: PAS level 1 with 10% assist, PAs level 2 at 25%, Pas level 3 at 35%, etc. But regardless of the PAS setting, the motor would continue to run right up to it's maximum speed?

 

[Diggs]

So I can set the speed limit to 100 in each PAS level, and increased the assist level for each PAS level? Would this allow me to travel at maximum speed no matter which PAS level I select? For instance: PAS level 1 with 10% assist, PAs level 2 at 25%, Pas level 3 at 35%, etc. But regardless of the PAS setting, the motor would continue to run right up to it's maximum speed?

Correct. You can set each level to 100% speed and just vary them by level of assist but and then it is like 90% of the other ebikes out there. (IMHO) you defeat the beauty of the BBSXX controller of having basically a cruise control while you pedal. No other ebike to my knowledge has this cruise feature of being able to set your speed and assist by level.

 

[rocketman58]

Correct. You can set each level to 100% speed and just vary them by level of assist but and then it is like 90% of the other ebikes out there. (IMHO) you defeat the beauty of the BBSXX controller of having basically a cruise control while you pedal. No other ebike to my knowledge has this cruise feature of being able to set your speed and assist by level.

Hmm. I'm not familiar with the cruise control feature.

I typically ride this trike with a group of other trikes or on long solo rides. I generally set the PAS level to 1 or 2 depending on the terrain or head winds. I like being able to select the level of assist and ride at any speed I like. I typically ride between 10 to 17 mph.

 

[Diggs]

Hmm. I'm not familiar with the cruise control feature.

Maybe cruise isn't the best way to put it. On my BBHSD set to PAS 3 I pedal along right about 15 mph and uses about 75 watts although I have PAS 3 set to use up to 550 watts. If I come to a hill and start to slow down it will add power (up to 550 watts and as long as I'm pedaling) to keep or bring back up to 15 mph. If I crest a hill and keep pedaling and go over 15 mph the BBHSD controller will dial back the assist eventually to nothing as there is no PAS needed to maintain 15 mph. Basically a cruise control while pedaling. Set the speed (in %) and the amount of power you want used (again in %) in each PAS level.

 

[rocketman58]

Maybe cruise isn't the best way to put it. On my BBHSD set to PAS 3 I pedal along right about 15 mph and uses about 75 watts although I have PAS 3 set to use up to 550 watts. If I come to a hill and start to slow down it will add power (up to 550 watts and as long as I'm pedaling) to keep or bring back up to 15 mph. If I crest a hill and keep pedaling and go over 15 mph the BBHSD controller will dial back the assist eventually to nothing as there is no PAS needed to maintain 15 mph. Basically a cruise control while pedaling. Set the speed (in %) and the amount of power you want used (again in %) in each PAS level.

I understand now, very cool.

 

[jonsully]

The Speed% governs how fast the chainring will spin. The Current% governs what percentage of the global current limit (I think usually 25 for BBS02?) can be used. Essentially once you start pedaling, the motor will kick in with the max Current% you've set to add power to the system up until the Speed% is reached. But again, Speed% is a measure of how fast the chainring is spinning, not your road speed. If you're in a low gear and the chainring is spinning at 100RPM, that's a lot slower than if you're in a high gear and the chainring is spinning at 100RPM. I should also note that the BBS motors decouple your foot/crank from the chainring, so it can actually spin faster than you're spinning (which is Ghost Pedaling and while some people don't mind, it's not my cup of tea).

Most folks over the years have accomplished better programming by limiting the Current%. This sets up a situation where the motor is constantly trying to reach its Speed% target but limited by how much current it can output. So it's always trying (and using some amount of power to do so) but never actually reaches the chainring speed it wants to get to. IMO these programmings burn extra energy and put more wear on the BBS components than they should.

I wrote a programming a while back that instead focuses on limiting via setting the Speed% to human-levels. The end-game here is to get the motor spinning the chainring at human-speed cadences (so as to avoid ghost pedaling) but that once the motor reaches that cadence, it should stop trying so hard and chill out. More here, if you're interested.

 

[Diggs]

But again, Speed% is a measure of how fast the chainring is spinning, not your road speed.

Actually, I believe it' a combination of the two and not just cadence. I've seen the formula but couldn't find it for this posting. It favors cadence but also takes speed into account. It's easy to check out when riding.

 

[rocketman58]

The Speed% governs how fast the chainring will spin. The Current% governs what percentage of the global current limit (I think usually 25 for BBS02?) can be used. Essentially once you start pedaling, the motor will kick in with the max Current% you've set to add power to the system up until the Speed% is reached. But again, Speed% is a measure of how fast the chainring is spinning, not your road speed. If you're in a low gear and the chainring is spinning at 100RPM, that's a lot slower than if you're in a high gear and the chainring is spinning at 100RPM. I should also note that the BBS motors decouple your foot/crank from the chainring, so it can actually spin faster than you're spinning (which is Ghost Pedaling and while some people don't mind, it's not my cup of tea).

Most folks over the years have accomplished better programming by limiting the Current%. This sets up a situation where the motor is constantly trying to reach its Speed% target but limited by how much current it can output. So it's always trying (and using some amount of power to do so) but never actually reaches the chainring speed it wants to get to. IMO these programmings burn extra energy and put more wear on the BBS components than they should.

I wrote a programming a while back that instead focuses on limiting via setting the Speed% to human-levels. The end-game here is to get the motor spinning the chainring at human-speed cadences (so as to avoid ghost pedaling) but that once the motor reaches that cadence, it should stop trying so hard and chill out. More here, if you're interested.

I will study the links you provided. I think I understand your explanation. The good thing is that I think I should be able to find a happy medium through trial and error.

 

[circuitsmith]

I ride mostly on city streets and prefer more assistance to get up to speed/cadence, then taper off.
PAS level 1 is minimal for riding around pedestrians etc.
Level 2-8 fairly close spaced. Nice for compensating the battery run down, fine tuning cadence.
Throttle always full beans.
52V BBS02.

 

[Diggs]

For those that aren't aware of it here is a great guide to programming the Bafang BBSXX -

A Hacker’s Guide To Programming The BBS02 & BBSHD

 

[jonsully]

Actually, I believe it' a combination of the two and not just cadence. I've seen the formula but couldn't find it for this posting. It favors cadence but also takes speed into account. It's easy to check out when riding.

It is not. Speed% maps exclusively to motor RPM, which is essentially rider cadence if you're matching your crank speed to motor RPM, though motor RPM does slightly change with battery voltage, as my guide walks through. If you're feeling like other things are impacting your ride, it's likely other vector / limits kicking in.

I wrote this programming (8 years after Karl first wrote the Hacker's guide !) specifically for people that want to pedal with the motor, not be ghost pedaling while the motor spins über fast beneath their feet. For those interested:

Sully's BBSHD Programming (for people that like pedaling) | Jon Sully

How to program a Bafang BBSHD to ride WITH the motor!

jonsully.net