USB Programming cable?

[lith.i.am]

Hi All,

I have this controller https://www.ebay.ca/itm/Ebike-BAFANG36V-250W-48V-500W-750W-Brushless-Motor-Controller-Replacement-Kits-/352866679972

and a Bafang DPC18 display all connected to a Bafang geared hub 500W geared hub motor. I don't like the way the pedal assist works. Each PAS level relate to a max speed and the power kicks in too sharply even in PAS1. I want to change it so each PAS level relates to a max power level, ie. PAS1 125W, PAS2 250W, PAS3 350W, PAS4 500W up to PAS5 750W. Also that it doesn't kick out 20Amps as you start to peddle. I think it should step up the power in stages.

How do I do this? (I don't really understand what needs reprogramming - is it the controller or the display). I see there are programming cables for BBSHD mid drives, but would they work with my controller?

Any help would be much appreciated.

 

[lith.i.am]

Here are a few photos of my build

 

[amberwolf]

I don't like the way the pedal assist works. Each PAS level relate to a max speed and the power kicks in too sharply even in PAS1. I want to change it so each PAS level relates to a max power level, ie. PAS1 125W, PAS2 250W, PAS3 350W, PAS4 500W up to PAS5 750W. Also that it doesn't kick out 20Amps as you start to peddle. I think it should step up the power in stages.

afaik, the "programming" is done via menus in the display. exactly which options are available to be changed depend on the controller version and what was left user-changeable by the manufacturer. not every controller will have the same settings available to be changed, and some may not have any settings other than stuff like wheel size. some of them have a password set preventing any changes (you can set your own password on those that don't have one already).

i don't see anywhere in the manual to change the stuff you want to change; my best guess is that you can't do what you want with what you have.

the display manuals are here
https://www.bafangusadirect.com/category-s/182.htm
http://nebula.wsimg.com/c96086c60a5156887a6b5be23addadd6?AccessKeyId=CBE8A380923DBA5825EC&disposition=0&alloworigin=1

and there are pages that explain some of the stuff in this search (i don't know which ones are better)
https://www.google.com/search?q=dpc18+manual


if you find you can't do it with those, you might look into the kt / kun teng / kunteng controllers, and the open-source firmware here on es, by casainho / stancecoke / etc.

there are probably other off-the-shelf solutions, but that would be more adjustable than anything else i can think of, short of using something like the cycle analyst v3 http://ebikes.ca to interpret your pas and/or throttle to do the things you want the way you want to. (if you have to use a ca v3, you don't have to put it on the handlebars, it can go anywhere it will fit, and setup/etc can be done via usb-serial to a computer, then a remote switch/knob put on the bars or somewhere convenient so you can change modes or presets while riding.

 

[lith.i.am]

OK thanks amberwolf :thumb:

I only got one day to play with it last weekend (when I finished the build) before the coronavirus lockdown here in Spain. Now we are not allowed out on bikes. I will have to try and see if I can get used it. The problems seemed to be with more 'mountainbikey' stuff and tight turns, but perhaps I could learn to use the throttle for the slow speed stuff. I may have made it a bit fierce by building a 52V battery and using a 750W controller on a 500W motor.

 

[amberwolf]

if you don't actually need that much power, (assuming there's really no way to set it in the display) then you can open up the controller and see how many shunt wires it has. if there are two, you can desolder and remove one to cut the current limit in half. if there are three, you can remove one to cut it by 1/3.

if there is only one, you could carefully shave some of it off, but this is a permanent, non-undoable modification (as is soldering on the shunt for more power) without replacing the shunt with an identical one (difficult to do as they're not marked with values, and they are not "just a piece of wire" even though that's what they look like).

this is basically what the shunts in a typical controller look like, and where they often are located.

some threads about modifying shunts, though they are usually trying to do the opposite of what you want.
https://endless-sphere.com/forums/search.php?keywords=shunt*+mod*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search