Fordulike,how can set up Keep Current program and what its purpose?
Thanks
Apologies for the delayed response SpezElec.
I'll try to keep it simple and add some examples.
The 'Keep Current' can be adjusted by using a programming cable and Bafang's programming software.
I got my cable from here:
http://www.empoweredcycles.com/products/usb-programming-cable-8fun-bbs02-mid-drive-motor
It works with both the BBS01 and BBS02 kits and is fairly simple to set up.
I can confirm the programming software works with Windows 10 too.
It allows you to adjust basic settings:
Pedal assist settings:
and throttle settings. I haven't got a screen shot of this menu as I don't use a throttle.
Your controller will have different settings to the ones in the screen shots. I was just playing about with different settings, to see how each one affects how the bike rides.
The 'Keep Current' basically ramps down the current to a percentage level of the PAS mode that the bike is in. This kicks in a few seconds after starting pedalling. This, I believe, it is an attempt by Bafang to help protect the motor and controller from over heating. It means that the unit will provide more amps for starting from a standstill, then ramp them down to the 'Keep Current' setting, for controller longevity.
Take an example from the 'Basic' screen shot above.
As you can see, even though the controller is a BBS02 25A unit, you can also limit the total amps that the controller will provide. In this case I set mine to 18 amps, as I didn't want to fry the controller whilst playing with the settings.
If I were to use PAS 4, then the controller will give me 18 amps x 48 volts x .50 = 432 watts of usable power when starting to pedal.
Then, If my 'Keep Current' setting on the 'Pedal Assist' page was set at 70%, it would ramp that 432 watts of power down to a maximum of 302 watts, once the bike is moving.
If I switched to PAS 9, then I would have 18 amps x 48 volts x 1 = 864 watts when starting to pedal, then it would ramp down to 605 watts max once moving.
I've probably made it all sound a bit more complex than it really is, and if anyone sees any mistakes in my calculations or facts, then please pipe up.
Once you have played with the settings and see how they affect the way the bike rides, then it becomes easier to understand.
I now have the controller set at it's full amps potential of 25 amps, but the 'Keep Current' is at 80%.
This gives me plenty of starting power, as it will peak at 1200 watts on the highest PAS mode when I start to pedal, but then only give me a max of 960 watts when moving.
This is equivalent of limiting the controller to 20 amps. Better for the controller and battery, than maxing all the settings and creating potential overheating problems for the controller and overloading the battery.