Fine tuning BBS02 750w 25A by controller programming

[Fordulike]

I thought I would share some discoveries with my BBS02, USB-Serial cable and programming software.
I won't give away who I bought my BBS02 from, as some companies like to keep certain info behind closed doors for whatever reason. I did try to obtain the original software parameters of the BBS02 kits that they sell, but they remained elusive, so I will respect that. Anyhow, I'm sure the regular members on this forum know where I got it from anyway

Since I started using the kit, I've always thought that the lower PAS setting were set a little too aggressive, and a look at the original parameters showed why.

Limit current(%) was set at 52% on PAS 1 and with the BBS02 max current set at the original 25A, was giving far too much torque assistance on start-up.

So after a bit of research and mainly thanks to Kepler over on Endless Sphere, I reprogrammed the basic parameters as follows:



Note that I lowered the Limited Current(A) from 25A to 18A. I haven't noticed a drop in performance, but that's probably due to another parameter I changed, which I'll describe further on. I believe that the lowering of the maximum amps that the controller can provide, is better for drive-train and controller longevity.

I did change back to having 9 levels of PAS for a few miles, but changed it again to 5 levels, as this suits my style of riding. In theory it's 6 levels, as PAS 0 is now functional, where before it didn't provide any assistance.

So on 5 levels of assist, I am using 0,1,3,5,7 and 9 on the list above, with their corresponding values.

The other parameter I changed was in the Pedal Assist menu. Keep Current was set at 60% originally,and I believe that once the pedal cadence increases, the controller drops the current down to 60% of whichever PAS level you are in:



In theory, this means that once up to speed the current level drops, possibly for economy. I don't really know
All I know is that if I dial in say 200 watts of assist, I want 200 watts of assist, no matter how fast or slow I pedal. I don't want it dropping off, especially up a hill. So I therefore changed the Keep Current to 100%.

Surprisingly, while I was riding with 9 levels, the assist corresponded quite uniformly as I increased the levels.
0=100w, 1=200w etc..

It appeared to overshoot less on the display's wattmeter too, and the controller seemed to be doing a good job of keeping the power within its limits.

Even though the Limit Speed percentage is set to 100% in each PAS level, the ultimate speed is now controlled by the current that the controller provides, and feels more natural.

In the lower levels, I don't feel that the bike wants to take me for a ride, it's me calling the shots, and in PAS 0 it feels so natural, giving just the tiniest amount of assistance.
I reckon in PAS 0 with 100 watts of assistance, the system just overcomes the extra weight of the bike and slight motor drag, to make it feel like riding a lightweight unassisted bike.

Overall, it's just less brutal and more refined, and I'm a firm believer as many others are on Endless Sphere, that 18A current limit is perfect for the BBS02. 25A is overkill!

I've not dabbled with any other settings and don't intend to either, as these suit me and the bike perfectly.

Bafang have done a reasonable job with the original controller settings, but one size doesn't always fit all, especially with electric bikes, and a bit of tweaking can transform a bike

 

[tony2311]

this is the exact setting i set on mine aswell. as i felt it was over assisted on low level. Hopefully my range will increase from 25miles

 

[Fordulike]

this is the exact setting i set on mine aswell. as i felt it was over assisted on low level. Hopefully my range will increase from 25miles

The original settings might work fine with a BBS01 250w, but too brutal on the BBS02 750w, as you discovered too Tony.

 

[Fordulike]

In my first post, I mentioned the 'Keep Current' parameter. I have a theory about this setting, as to why Bafang have set it to 60% on the 48v 750w 25A unit.

As I said, I believe the 'Keep Current' parameter steps down the current, to a percentage of the PAS 'Limit Current' setting on the 'Basic' page of the controller program.

Let's work with the theory that you run the unit everywhere in the highest level, which means the controller is giving everything, 100% current and 100% speed.

With a 48v battery and 25A controller that would be 48 x 25 = 1200w

Now Bafang rate this particular motor at 750w. So my theory is that once the pedal cadence is increased, the controller applies the 'Keep Current' setting, and steps the output down to its value in the 'Pedal Assist' page of the controller program.

I.e. 1200 / 100 x 60 = 720w

With slight fresh battery voltage variations, this would vary a little, but still be fairly close to the motor's rated power.

Obviously, on other PAS settings, the 'Keep Current' would step the power down to a percentage of the percentage of the units max current delivery. Note, you can also change this from the factory default.

It would be interesting to know what the settings are on the other models in the range, and to whether my theory is correct or a load of old tosh

 

[Fordulike]

Always eager to prove my own theories, I programmed the controller back to its original 'Keep Current' setting of 60%, plus 25A max.

Without a rolling road test facility to load the rear wheel in a more scienftific and controlled way, I set out to test the bike on a local steep hill.

I tested on PAS 5, which is set at 100% current, 100% speed, which should allow the controller to give it everything.

I noticed that from a standstill on the hill, with a good load on the motor, it would momentarily peak over 1000 watts, then quickly settle down to around 800 watts.

This ties in with a fresh 48v battery and 25 amps stepped down to 60%.

No matter how much load I put on the motor, it would not go over 800 watts once moving.

After a few runs up the hill, I did notice that cadence didn't appear to make any difference to the output. I.e. no matter how fast or slow I pedaled, or what gear I was in, it still peaked at 800 watts.

My conclusion is that the controller only gives maximum amps to the motor on initial start-up, to help with getting moving. Once going though, it tames the power for controller/motor longevity (due to heat build-up) and better battery life and economy.

Apologies if I've bored the pants off you all, but as I get older, I'm becoming more intrigued in how things work

 

[tony2311]

48v x 18amp 100% = 864
48v x 25amp - 60% = 720
which is the better setting?
i presume it will be the second one as it will reduce battery power used
or will it be better
48v x 20amp 75% = 720 for power and battery life?
am i talking rubblish? what have you set it up as?

 

[Fordulike]

48v x 18amp 100% = 864
48v x 25amp - 60% = 720
which is the better setting?
i presume it will be the second one as it will reduce battery power used
or will it be better
48v x 20amp 75% = 720 for power and battery life?
am i talking rubblish? what have you set it up as?

Probably the first one if you want to give the battery an easier time, as the max amps drawn will always be limited to 18 amps (864 watts). Whereas the second setting can peak at 1200 watts, then settles down to 720 watts.

I'm still using the settings from my first post, but I rarely go greater than PAS 3 in 0-5 mode. PAS 3 on my display correlates to Assist 5 or 60% Limit Current on the 'Basic' list.

 

[Fordulike]

Just to add to the discussion on changing the 'Keep Current' value.
I use my bike mainly on forest tracks and short, steep, muddy and loose gravel paths.
Therefore, quite often I need a burst of torque for short periods of time.

The 'Keep Current' set at 100% is a good way of maintaining that torque whilst travelling up a hill, as it will keep the power delivery consistent.

'Keep Current' at 60% will drop the current available after you've committed to the hill, and the way to compensate is to either pedal harder or increase the PAS up a level.

Once committed, I don't want to be faffing about increasing PAS levels, or pedaling like my life depended on it, so 100% 'Keep Current' works for me.

I would recommend that you think carefully before changing this parameter, depending on the way you ride. If you are riding with the 'Keep Current' at 100% and use high PAS levels, then this will be a recipe for battery damage, controller damage or both.

 

[One_Box]

Nice write up

Your conclusions are in line with mine and those at Electric-FatBike.com. ( this site has basically distilled the information on Endless Sphere into two excellent articles giving recommended parameters from 4 different sources and an explanation of what each does.)

Anyone thinking of programming their BBS01/02 should look at that site first.

Personally I have raised the "keep current" from 20% (Woosh setting) to 60% on my BBS01. I only ride on the road however and am more concerned with a good range from my 15Ah battery than absolute power.
All the changes I made are on my Pashley Parabike conversion thread.

 

[Fordulike]

Nice write up

Your conclusions are in line with mine and those at Electric-FatBike.com. ( this site has basically distilled the information on Endless Sphere into two excellent articles giving recommended parameters from 4 different sources and an explanation of what each does.)

Anyone thinking of programming their BBS01/02 should look at that site first.

Personally I have raised the "keep current" from 20% (Woosh setting) to 60% on my BBS01. I only ride on the road however and am more concerned with a good range from my 15Ah battery than absolute power.
All the changes I made are on my Pashley Parabike conversion thread.

Crikey, there's controller preservation, then there's taking the michael.

I can imagine 'Keep Current' at 20% would dull the motors performance to such a level, as to there being next to zero ebike grin when riding.

Bet you noticed a big difference moving up to 60%.

I've been playing around again today, and I changed back to Bafang's factory settings, but increased 'Keep Current' to 80%.

This keeps it in line with the battery's 2C rating and provides a big grin factor

Anyone following my programming changes, please don't blame me if things go bang. My riding style warrants always being in a suitable gear, plus I'm running a smaller 42T chainring.

 

[One_Box]

Absolutely, when I first took out the Pashley with the stock BBS01 settings I covered 75 miles and over 5000 ft of climbing and wondered where the power was ( compared to my Kalkoff ). Now the bike is transformed and Is an absolute pleasure to ride and is so quiet ( Kalkoff eat your heart out ).

 

[Fordulike]

Absolutely, when I first took out the Pashley with the stock BBS01 settings I covered 75 miles and over 5000 ft of climbing and wondered where the power was ( compared to my Kalkoff ). Now the bike is transformed and Is an absolute pleasure to ride and is so quiet ( Kalkoff eat your heart out ).

So correct me if I'm wrong. I'm assuming that you got the BBS01 36v 350w version with the 18A max current limit.

With 'Keep Current' programmed at 20%, that would have given you a useable assistance of only 130 watts, and an amp draw of 3.6 amps.

Mmmmm, I can understand sellers programming units to minimize any warranty claims, but 130 watts... Really

 

[One_Box]

Mine is the 250W version with max current of 15A. Of course I could change it to 350W by changing the max current to 18A but I have no need.
It would be interesting to know if anyone else has a Woosh supplied BBS01 with "keep current" set to 20%

 

[Fordulike]

Mine is the 250W version with max current of 15A. Of course I could change it to 350W by changing the max current to 18A but I have no need.
It would be interesting to know if anyone else has a Woosh supplied BBS01 with "keep current" set to 20%

That's even worse, 108 watts!

The breeze round my way is stronger

 

[One_Box]

That is why I have keep current at 60%. With a nominal efficiency of 80% the motor is producing 259W on level 9 once it has settled down. This is fairly near the legal max of 250W. Of course I could reduce it further but I'm reasonably happy where I am.
I notice you have slow start at 5 and current decay at 8, do you get any hunting at all ?

 

[trex]

...
It would be interesting to know if anyone else has a Woosh supplied BBS01 with "keep current" set to 20%

woosh don't reprogram the controller, the kits are supplied as shipped from 8-Fun. I have a programming lead to play with my kit but shamed to admit that I did not find any need to change anything.

 

[One_Box]

I accept that Woosh do not reprogram their BBS01/02 kits prior to sale.
It is obvious looking at threads on this forum and Endless Sphere that Bafang do not necessarily provide identical programming to every retail outlet. Otherwise everyone would be starting from a common position which clearly they are not.

The other unknown ( at least as far as I'm concerned ) is the effect the software version has.