EDIT: 4/20/21; After 3 years my fix described in this post quit working. I didn't try to figure out why, simply removed it to make sure everything worked as originally shipped from Bafang. Also, I had another fix I wanted to try which is simple and requires no electronic parts. I completed and tested this alternate fix today and I'm planning a simple enhancement to make it's use completely transparent. First I cut the grey PAS sense wire in the middle, which effectively shuts down the PAS. Then I spliced a wire onto each of the grey wires and ran the wires out of the controller through a small notch cut into the rubber wire entrance area. I used a small two wire conduit long enough to reach the handlebars where I connected them to a toggle switch. Now if the toggle switch is closed the circuit between the grey wire ends is completed and the PAS works, but with the original throttle problem. When the toggle switch is open the PAS does not work but the throttle works properly whether or not you pedal.
My enhancement thought during my test ride is to install a small normally closed momentary button switch right where your thumb goes on the throttle. Then when you choose to use the throttle the button switch will open the circuit and the throttle will work properly. Here is a link to the type of switch I am talking about:
I have decided against any modification to the throttle because of possible negative effects on the throttle. I have started a new thread for discussions concerning this simple fix here:
As most BBS02 and BBSHD enthusiasts know, Bafang introduced a change in 2017 that changed dominance from the throttle to PAS which resulted in poor throttle response when you were also pedaling, even in PAS level 0. I took part in an experiment with guidance from Fechter to make an electronic...
endless-sphere.com
EDIT 5/29/19: There is finally a possible programming fix for this problem. Here is a link to a thread that you need to read (BOTH PAGES) if you are experiencing this problem: Update on 10/13/19, there is no confirmation that these firmware flashes fix the pedal/throttle issue. I will leave the following link in place, since there is a lot of information there pertaining to firm ware flashes:
EDIT: ***EVERYTHING*** I know about this, all the information I have about this, is here in this thread; please don't PM me for more info (I don't have any), just ask in this thread, and maybe someone else will know. First: You accept all responsibility for performing any or all of the...
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EDIT: Fechter has completed and tested a simpler fix for this issue. See his solution five posts down on this page.
In August of 2017 I purchased a new BBS02 and something seemed to be wrong with it. It did not operate the same as the previous five BBS02 kits I had purchased and installed over a period of four years. Since then there have been many threads addressing this problem, but the dealers I have contacted could not offer a fix, (LUNA did exchange the “faulty” controller for an older good controller), and Bafang did not even respond to my questions.
THE PROBLEM:
While pedaling, in any PAS level, 0 through 9, the throttle would not work, unless you went to full throttle. This resulted in lots of jerking and stress on the drive train, etc. In PAS 0 you were unable to use partial throttle and pedal at the same time. Although the hardware and firmware versions were unchanged, Bafang apparently made an internal change to the controller that caused this problem. All of the BBS02 controllers manufactured after 2016 apparently have this problem and perhaps some of the BBSHD controllers also have this problem.
I.e., in the older controllers, when the throttle is used the PAS system is disabled and in the newer controllers, when the pedals are rotating the throttle is disabled.
EDIT: There are a couple of technical details concerning the above simple statement, just so the accuracy of this statement does not become the focal point of any further discussion: First, in the older controllers whichever was greater, either throttle or PAS dictated which input controlled the motor. The result is the same, since there would be no reason to use the throttle when using PAS and also pedaling unless you wished to override the PAS system and speed the motor up, and; Secondly, in the newer controllers when I say the throttle is disabled, I am aware that the throttle still cuts in when you reach the full throttle position, but the full range of the throttle is disabled, and a throttle that just works like an on/off switch and only gives you full throttle is a disabled throttle IMHO.
THE FIX:
Recently on another thread concerning this problem a discussion ensued between Alan B and fechter on possible DIY fixes. I joined the discussion and with a lot of patience and guidance from fechter, have now completed and road tested the following fix on a faulty 2017 controller. This fix interrupts the PAS signal when the throttle is used so that the controller does not know that the pedals are turning. This fix is delicate and would void any warranty you might have.
With the controller off the BBS02 I very carefully removed some of the potting where the external wires entered the controller area, back to where the individual wires came out of the outer sheathing. The only wire I was after was the blue throttle signal wire so I carefully removed about the last inch of the outer casing from the main wiring harness that leads to the display and brakes. This was the most difficult part of the fix. If I were to do it again I would gain access to the blue wire at an external point and run the lead into the controller through a new hole drilled on an upward angle near the top of the grommet. Then there would be no need to further disturb the potting or other wires in that immediate area.
Next I exposed about 1/8” of wire within the insulation of three wires by first making a small cut in the insulation and then pulling the insulation back with my fingernails. The three wires are the blue throttle wire previously mentioned, the grey PAS sense wire, and the black PAS ground wire. The PAS wires were already exposed in the controller area and are two of the four wires on one of the mini plugs.
With the three wires bared a lead wire was attached to each. You could do this with good solder skills, but I used Silver Conductive Epoxy. Then these taps were coated with liquid electrical tape.
One end leg of a 100K trimmer resistor, Mouser part # 652-3296W-1-104LF, was attached to the blue throttle lead, the middle leg of the resistor was attached to the base leg of a transistor, Mouser part # 610-2N5550, using a short wire for flexibility, and the other end leg of the resistor was attached to the black PAS lead. The collector leg of the transistor was attached to the grey PAS lead and the Emitter leg of the transistor was attached to the black PAS lead.
Then all the connections were coated with liquid electrical tape and everything was wrapped with electrical tape with just the adjustment screw end of the resistor showing.
Final adjustment was made by trial and error testing with the controller uninstalled but all wires connected.
This diagram was copied from a post by fechter on another thread:
View attachment 233108
IN CONCLUSION:
IMHO the need for this fix should not even exist. Bafang made a manufacturing mistake and even when the dealers were alerted to the problem by their customers, instead of working with Bafang to find a solution, they just continued selling the kits.
Even though I am happy with my BBS02 kits, I can no longer recommend them. It’s been eight months since I came across this issue and AFAIK every new BBS02 currently for sale still has the faulty controller in it.
If anyone can provide any rationalization why making the throttle inoperative when pedaling was an improvement or had any value to anyone I would like to hear it.
