DIY Fix for BBS02/BBSHD Pedal/Throttle Issue

Well, here's a data point anyway. Just bought a BBS02 from Luna with a controller dated 11/20.


Has "The Issue".

If there's such a thing as a BBS02 controller fixed with firmware I can't find one.

I also still haven't heard anything reliable about why Bafang started making the PAS over-ride the throttle. I'd really like to know.

My speculation is that it has something to do with the different classes of ebike being distinguished by whether they have a throttle or not (in California anyway). (Class 1-no throttle. Class 2-throttle only). Maybe in some twisted logic, Bafang thought that making the throttle and PAS less "intertwined" addressed this somehow.

fechter said:

That's it. Just unplug it.
There is usually a little blob of silicone holding the plug but you can just pull hard and it will tear or you can slice it with a blade first.

If you're sure you won't ever want it again, you can also just snip the grey wire and leave the plug in.

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Hi, I got my BBS02 up and running today. I disconnected the PAS as advised, I thought that would disable all the PAS system, but every time I turn it on I have to scroll the PAS to #5 on my display to get any decent power at all. It does work on throttle alone, I don't need to pedal, but it soon runs out of revs, like it's rev-limited, and I keep having to shift up gears really quickly. Have I missed something please? Cheers

There are settings in the programming you need to change. You need the programming cable and the software. There are several other topics talking about the programming. On mine, I have the throttle programmed to always give full power with no speed limit regardless of PAS setting. Sounds like yours is programmed to be a function of the PAS setting.

Quite a few people have reported good results with upgrading the firmware to solve the throttle problem. I can't say for sure it will work on a BBS02 and may be vintage dependent. Same cable is used to load firmware.

Sure thought I had followed fecter's instructions to the "t" here. But no joy. Still have the PAS over-ride on spare BBS02 controller after modification.

I used :

512-KSP13BU

KSP13BU
ON Semi Darlington Transistors
US HTS:8541210095 ECCN:EAR99 COO:CN

and

71-RN55D-F-100K/R

RN55D1003FRE6
Vishay Metal Film Resistors - Through Hole
US HTS:8533210090 ECCN:EAR99 COO:US


and its a controller dated 9/16.


Any advice?

I think you have the two outside legs swapped around. The emitter should go to ground. Try reversing them.

Got it! Works perfectly now. I suppose I probably should have first made an attempt to understand how a transistor works (i. e. understand which leg is the emitter) before I did this modification. But I guess this proves anybody, regardless of their understanding of electronics, can do this.

Can't thank you enough fechter. You (and Rassy et. al.) have done an invaluable service here.

If I could only get Bafang and their distributors to be as helpful and forthcoming.

Thank you!

Well, after 3 years of regular use the controller dated 9/2016 that I "fixed" started cutting out on a ride today. The display stayed on so I knew power was getting to the controller, but the assist would stop and the throttle would not work. Most times after losing three or four MPH both the throttle and the PAS would kick in again for a while. Then I discovered that with just fairly high throttle usage it did not cut out until I had to slow down. So I went to PAS level 0 and rode for several miles just using the throttle and had no more issues. I will pull out the controller and see what I can find and report back. If nothing is obvious I will probably replace the entire fix with new parts.

Too bad for me, but I traded off a good BBS02B that I had on the shelf to a local friend for a new trike he had purchased. About a week ago the controller in his BBS02B stopped working completely and I swapped it out for the last good early date BBS02B controller that I still had on the shelf. That controller came out of the BBS02B that started giving me problems today and I had never replaced it because the "fixed" controller worked as good as the original, at least for 3 years until today!

Just for interest, In early February I was having some winter blues along with covid blues and decided it was time to treat myself to a 48V torque sensing PAS TSDZ2 with a throttle and a VLCD5 display. My plan was to install it on the very trike that I had problems with today, but even though the trike had a Bafang BBS02B on it the Tong Sheng TSDZ2 would not clear the frame member. Not to be cheated out of experiencing torque sensing VS Cadence sensing PAS I purchased a new trike that the TSDZ2 could be installed on only to then discover I had been sent a 36V unit instead of the 48V unit I had purchased. Now due to backlog issues I am still waiting for my 48V unit. I'll start a new thread for the build when I fill like it.

EDIT: I finally got the correct TSDZ2, but I didn't like it at all. Unlike the BBS02, which you can set up the way you want it, the open source programming available for the TSDZ2 is very complicated looking and did not excite me at all. The problem for me is that I am old and don't have the energy or stamina to apply enough pressure on the pedals to unleash the power within. The TSDZ2 will be going to a friend for his Trek bike. He is a strong pedaler and excited about testing the torque PAS.

I was wondering if anyone could help with my issue. I ordered a BBSHD from Luna this month, and I think I might have the throttle issue described in this thread. I ordered mine with the "universal thumb throttle."

My issue is this: under any PAS setting, the throttle only operates at either 0% or 100% wide open. There is no in-between, or progressive ramp up with the throttle, it might as well be an on/off switch. There's 6 different PAS settings on my display, 0 through 5, and the issue is the same no matter the PAS setting. This was verified by putting my bike on a bike stand and testing the throttle with the rear wheel off the ground.

Also, the PAS system seems to work the same way when using the pedals rather than the throttle. There is only one motor speed that the BBSHD seems to work at, 100%, again there is no variable speed that changes depends on the pedaling speed. I don't know if this is how to BBSHD PAS is designed to work but it seems like a pretty crappy implementation, because at any PAS setting over 1 the motor completely outpaces any human effort, turning it into "ghost pedaling."

I don't really care about the PAS issue but what would be the best step forward from here to fix the throttle? Contact Luna or attempt to do the fix outlined by Fetcher in this thread? Has anyone contacted Luna about this issue, and what was their response? I would prefer they replace the controller or offer another fix rather than have to tear apart the BBSHD myself.

The throttle issue sounds like mine. Several members have reported good results by flashing new firmware to the controller to fix the problem. I can't vouch for compatibility of any firmware versions. My hardware hack will work regardless of firmware version.

The PAS problem can be improved by changing the PAS settings in software. The stock settings are terrible and function like you describe. Even with optimized settings, it still sort of sucks because there is no torque sensing on the pedals.

You use the same programming interface to do both things. Maybe try to talk Luna into giving you one.

My fix, described in the first post of this thread, died after 3 years of use. I have updated the first post with an edit describing a very simple alternate fix for this problem that does not require any electronic parts or digging into the controller potting. Of course it will still void your warranty.

EDIT: I just purchased a BBS02 that was manufactured just last month. To my disappointment it suffers from the PAS/Throttle issue Bafang introduced in 2017, and I will be doing some work on it soon. I wanted to mention here that this new BBS02 had the worst programming I have ever encountered, namely it jerked the drive chain when operating in any PAS level every time you stopped pedaling and then resumed pedaling. Also, the throttle never supplied any more power than the various PAS levels you were sitting in. After resetting many parameters all is good in this area.

Can you post a picture of how the button is mounted?

Also, some reports indicate the "fixed" version of BBSHD firmware will also work on the BBS02 but I can't confirm.

Excellent question fechter, I decided against making any modification to the throttle and instead I'm using a latching button switch next to the thumb on the opposite side of the handlebar from the throttle. Since this thread has become quite long and mostly about the electronic fix to the problem I have started a new thread for discussions concerning this very simple fix:

https://endless-sphere.com/forums/viewtopic.php?f=28&t=111469

fechter said:

The throttle issue sounds like mine. Several members have reported good results by flashing new firmware to the controller to fix the problem. I can't vouch for compatibility of any firmware versions. My hardware hack will work regardless of firmware version.

The PAS problem can be improved by changing the PAS settings in software. The stock settings are terrible and function like you describe. Even with optimized settings, it still sort of sucks because there is no torque sensing on the pedals.

You use the same programming interface to do both things. Maybe try to talk Luna into giving you one.

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fetchter, as you can tell from my post count, I'm new to this site/forum, but I have researched lots of sites quite a bit in preparation for the install of a BBSHD on my '08 Santa Cruz Nomad...looking for the pros, cons, and experiences of others. I ran across this specific post about the Throttle and PAS, saved the thread, and kept the issue in the back of my mind.

I bought a partial kit from Bafang USA the first of April which included the motor and 500C display. I got the rest of the items mainly from Luna including the program cable. This setup is pretty much dedicated only to true, off road mountain biking trail use. The first outing with an unmolested program exhibited the usually mentioned abruptness and extreme power "kick-in" at unwanted times on a tight trail. I didn't putz with the throttle on this first ride, as I was just trying to get used to riding an MTB with a motor. I work part time at a bike shop as a mechanic and have tried our Trek and Specialized emtb's...quite another animal with torque sensing of course.

Anyway, back home and did a couple of tweaking sessions on the program and really smoothed out the power delivery for off roading. I also really tamed the throttle input down where it became more usable. That's when it struck me that my throttle works seamlessly while pedaling with pedal assist. It was smooth through out the range with or without pedaling. I was expecting the annoying glitching as described by most here with the throttle and PAS. So, I think you're right about some of these units not having that issue anymore, at least perhaps on the BBSHD. I doubt anything I did in the reprogram eliminated the problem I had seen described. I just did the often standard approach of softening up the throttle and getting it to respond on its own under assist level 9. So, from this do you think that annoying element was removed in some units or am I missing something? I'm not complaining because the way it functions now is excellent. I mainly use just pedal assist when trail riding, but the smooth introduction of throttle has been nice when sort of stalling in a rock section or starting from a stop in a rock section when you're trying to clip in and start rolling. As a life long dirt motorcycle guy, I'm used to having some power kick in with a throttle, so this has not seemed an alien experience to me...and frankly the throttle is one element I think is useful in key situations that is missing in most factory emtb's.

The newer units appear to be shipped with the "fixed" firmware so it sounds like you got lucky and have the good firmware version.

One trick I learned was if you want to cut the power instantly while using the PAS, just pedal backward. Otherwise the motor keeps going for a split second which can be bad in a technical situation. I find the throttle useful when starting out on a steep hill or when you want to keep the cranks up for ground clearance.

fechter said:

The newer units appear to be shipped with the "fixed" firmware so it sounds like you got lucky and have the good firmware version.

One trick I learned was if you want to cut the power instantly while using the PAS, just pedal backward. Otherwise the motor keeps going for a split second which can be bad in a technical situation. I find the throttle useful when starting out on a steep hill or when you want to keep the cranks up for ground clearance.

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On that first outing I described with the OEM delivered program, I was using my hydro brake cut-off switches by tapping the brake lever(s) to kill the motor coming into turns and such where the motor was wanting to keep running, as you know. After slowly getting my head around the listed tuning elements in the program and the experiences recorded by others, I think I've smoothed out that tendency at "overrun", if I understand that description properly. Still, it's very much like riding a dirt motorcycle where you come into the corners or dodging around obstacles, and you always get on the brakes to stop or slow down the momentum of a 250-300 pound dirt bike in those cases. The brake cut-off switches are working well for me in a similar way.

Speaking of dirt motorcycles, I'm noticing on a couple of the off road motorcycle forums I'm a member of that some of those folks have Bafangs and really like them on their previously pedal-only MTB's. I get the impression that dirt motorcycle riders may take to the power characteristics and aggressiveness of the mid-drives a little easier than those who've only been MTB riders. Just an anecdotal observation, no science involved...LOL! I'm loving the way these motors can be tweaked to better fit riding preferences, and I want to thank folks like you and the many others who have submitted a lot of detail on tuning options, pros, and cons.

I'm a long time motorcycle rider and rode my BBSHD for over a year with the PAS disabled. Throttle only. It was very natural to me and even after fixing the PAS, I still go with throttle quite often for more precise control.

Interestingly, I was recently stopped by a park ranger who asked me if my bike had PAS. I told him it did. He said that throttles are not allowed on the park trails. I really don't understand where they come up with stupid rules like this. So to really be compliant, I'd have to disable the throttle when on park lands, but it would be OK on the street. What I do instead is I always pedal, whether I'm using the throttle or not and I don't ride like an ass.

fechter said:

I'm a long time motorcycle rider and rode my BBSHD for over a year with the PAS disabled. Throttle only. It was very natural to me and even after fixing the PAS, I still go with throttle quite often for more precise control.

Interestingly, I was recently stopped by a park ranger who asked me if my bike had PAS. I told him it did. He said that throttles are not allowed on the park trails. I really don't understand where they come up with stupid rules like this. So to really be compliant, I'd have to disable the throttle when on park lands, but it would be OK on the street. What I do instead is I always pedal, whether I'm using the throttle or not and I don't ride like an ass.

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That's interesting on the park ranger incident. I wonder how many park rangers really know the nuances of these emtb's and their operational elements? Maybe they have some training on this issue, but can you imagine trying to know all the particulars of each system on every bike out there? I go to the Big Bend area of Texas every late fall to ride my street legal 300cc bike. In the NP I notice more and more ebikes of various styles there. So far I haven't seen any enforcement issues from rangers or problems with the riders themselves. Now, they are staying on the paved roads and even some of the gnarlier jeep roads, so I think all is pretty much legal as to how they're operating.

I received a new BBSHD from Luna and I’m happy to report the throttle problem is indeed fixed!

I find it truly amazing that 4 years on the issue still exists. I've just purchased the BBS02b variant in May 2021 and in all honesty, i am a total rookie when it comes to DIY repairs. Now that it's built I feel like I'm experiencing this same problem. It is extremely noticeable becasue I've just stepped away from a Fiido DS2 and a Raleigh Motus with a bosh mid-drive. I feel this certainly takes the fun away from cycling a bit because the main reason for my change to a torque-sensing motor was to take away pressure from my knees and when I get bored give the throttle.

To the point, now that I have established I have the same problem my 1st question is, does the software changes resolve the issue?
If not, I understand the hardware modification posted by Fetcher works regardless, my question is what is the risk with going down this route other than voiding the warranty?
With the p60 display is there a way to have throttle mode at level 0.

From reading all the comments I'm gutted that I didn't get the BBSHD as that seems to have solved the issue.

Just for the record I sent an email to Luna Sales yesterday and asked specifically about the status of the Throttle/Pas issue. Here is the response I received today:

"The throttle/pas issue has not gone away. It is still there but you can "mask" it or "cover it up" with

the proper programming. That is what we do with our controllers. We program them

so that it's not an issue like before. "

Unfortunately It is still an issue as far as I am concerned.

As an update, I am quite satisfied with my simple solution of running a pair of wires (in a small conduit) from the severed gray Pas signal wire to a rocker switch on the handlebar. Turns out I can make a smoother transition from Pas to Throttle and vice versa then either the original controllers or those with the electronic fix. My throttle is near my left thumb and the rocker switch is under my right thumb and when both are hit at the same time there is no lag at all.

I'd recently convinced a friend to purchase a 750W bbs02 and while fitting it noticed the throttle/PAS problem. My bbs02 is from 2015 and doesn't have the problem, so I didn't know what was going on at first. Eventually I came across this thread - thanks guys.
I soldered a lead to the grey PAS wire in the motor and routed it out between the rubber cable seal.
No need to dig for any wires.
I split the throttle cable by the plug on the main harness and soldered wires to the blue and black wires.

I wired up 2 BC547B ( it all I had lying around) as a darlington pair with a 20K resistor on the base.
Set the throttle programming to 11 and 41 start/end voltage.

It's now perfect, the throttle comes on gradually under PAS, no hestitaion, really smooth. The PAS comes straight back on when releasing the throttle.

Thanks again for the diy fix.

This is simply an update to this thread relating the example of my recent experience. Fortunately I haven't had the problem outlined here with any of the BBSHD bikes I have built. In September of this year I built a bike with a BBS02 I purchased from Luna. This motor/controller does have the PAS/throttle issue. The tech support person I contacted at Luna was not aware of any such problems. You can easily flip yourself over on your back with the throttle on this bike. None of my BBSHD bikes could or would do that.

I am currently looking for a source of Darlingtons. The joys of supply chain.

Cheers and thanks for this thread.

YOu can make yourself a darlington the same way they originally did, by wiring two regular transistors of sufficient gain (and the right other properties for your setup) as a darlington pair.


https://en.wikipedia.org/wiki/Darlington_transistor

In electronics, a multi-transistor configuration called the Darlington configuration (commonly called a Darlington pair) is a circuit consisting of two bipolar transistors with the emitter of one transistor connected to the base of the other, such that the current amplified by the first transistor is amplified further by the second one.[1] The collectors of both transistors are connected together. This configuration has a much higher current gain than each transistor taken separately. It acts like and is often packaged as a single transistor. It was invented in 1953 by Sidney Darlington.

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hrasco said:

I am currently looking for a source of Darlingtons. The joys of supply chain.
Cheers and thanks for this thread.

Click to expand...

Pretty much any NPN Darlington will work. Some may have different pinouts or package sizes.
There is a way to update the firmware on the controller to solve this problem
See this topic:
https://endless-sphere.com/forums/viewtopic.php?f=28&t=100064