Throttle Behavior

automan25

100 mW
Joined
Feb 5, 2017
Messages
44
I read on a forum a month or so ago that when pedaling the throttle behaves in an on/off manner (i.e., full wattage or nothing). If one is not pedaling, then the throttle behaves as expected with some degree of modulation. I was finally able to test it out this morning on my bike (BBSHD with left thumb throttle) and sure enough, I get the same result. I even tried setting PAS to zero and pushed the throttle while pedaling, but still get the same on/off behavior. Obviously I'd like to have throttle modulation while pedaling. Has anyone overcome this issue?
 
Apparently this happens when the controller is made for a gear change sensor. I had this issue too, and gave up by snipping the grey PAS wire to completely disable the PAS. Now I have throttle only but it responds properly. Other option is to find the right controller or install the gear change sensor.
 
Interesting. I have the gear change sensor installed (though it doesn't work very well). I wonder if I remove the sensor if the throttle would behave normally. Perhaps there is a way to cut the wire to the sensor and bridge the connection so the controller behaves as though the sensor wasn't there.
 
I have been pursuing this issue since it first caught me on a BBS02B. It is apparently related to the date the controller was manufactured and not the existence of a gear sensor. I am currently awaiting a reply from Bafang concerning this issue.

Here are the serial numbers of the controllers I have tested and what I am basing my above statement on. The first digits of the serial number indicate the year, month, and day of manufacture:

1605180028 with gear sensor worked normally;
1609270057 with no gear sensor worked normally;
1705310074 with gear sensor had the throttle/pedaling issue; and
1709140337 with no gear sensor had the throttle/pedaling issue.

My current theory is that there are some settings on the V2.0.1.1 firmware that were not available on the V1 firmware, and the Bafang software that Penoff modified does not give you access to these settings. If/when new software is available this problem might be solvable.

Of course this is just my guess, but I would be interested to see the serial numbers that others have and whether or not they experience this throttle problem when pedaling.
 
automan25 said:
Interesting. I have the gear change sensor installed (though it doesn't work very well). I wonder if I remove the sensor if the throttle would behave normally. Perhaps there is a way to cut the wire to the sensor and bridge the connection so the controller behaves as though the sensor wasn't there.
In my above post, when I say the controller has the gear sensor I only mean that the cable for a gear "change" sensor is attached to the controller. I have never installed an actual sensor to the shifting cable. I currently don't think "removing" or somehow disabling the gear sensor would affect this issue.
 
Thanks for the information Rassy. I'll take a look (hopefully this evening) to see what my serial number is. Where should I look on my BBSHD for the number?
 
Where should I look on my BBSHD for the number?

I've never had a BBSHD, but on the BBS02B there are 3 rows of numbers/letters on the upper side of the controller part. Shine a light in front of the crank and just inside of the chain wheel and final reduction gears. The date/serial number is the third row.

For those with a BBS02 the original controllers only had two rows of numbers/letters.
 
Rassy said:
automan25 said:
Interesting. I have the gear change sensor installed (though it doesn't work very well). I wonder if I remove the sensor if the throttle would behave normally. Perhaps there is a way to cut the wire to the sensor and bridge the connection so the controller behaves as though the sensor wasn't there.
In my above post, when I say the controller has the gear sensor I only mean that the cable for a gear "change" sensor is attached to the controller. I have never installed an actual sensor to the shifting cable. I currently don't think "removing" or somehow disabling the gear sensor would affect this issue.

I'd like to know how this works too, having had the same problem.

Question: If the gear sensor is installed, does the throttle then behave properly? If so, then it should be possible to 'spoof' the signal without actually having the sensor. Maybe a couple of resistors or something might do it.
 
fechter wrote:
Question: If the gear sensor is installed, does the throttle then behave properly? If so, then it should be possible to 'spoof' the signal without actually having the sensor. Maybe a couple of resistors or something might do it.

If you look at my first post on this thread you will see that I tested a new controller that had no gear sensor/cable at all, i.e. no dedicated gear sensor, but that controller also had the Throttle/Pedal problem.

I found that controller on an Aliexpress site, verified it had no dedicated gear sensor, and purchased it in the hope that it would work properly. But alas, it also had the problem that I thought up until then was directly related to the dedicated gear sensor.

Also, my contact at LUNA had eventually told me that the problem was more likely to be related to the date of manufacture than to whether or not the controller was manufactured with the dedicated gear sensor. LUNA exchanged my controller from 2017 that had the issue for a used controller from 2016 that didn't have the issue. I was actually surprised when the used controller arrived last week that it had a gear sensor cable, but I installed it and tested it and it works properly, i.e. it does not have the Throttle/Pedal problem.

So my conclusion is that the gear sensor itself is not the problem, and therefore the problem probably can't be corrected by any modification to the gear sensor (cable) that is installed on the controller.
 
Interestingly enough, I have a Mxus 3000w rear hub, and KT Kunteng Controller, with KT LCD6 display, and KT PAS sensor kit on this also works in exactly the same manner as you describe.
Throttle only, perfect modulation, PAS only perfect level of assist according to level set. As soon as you touch throttle when in PAS mode, you gain instant maximum power. Similarly if you are using the throttle and simultaneously begin to pedal, maximum power is produced.
I have got used to this now, and find it useful when I want a quick burst of full grunt, but it would be nice if it were possible to combine the two inputs in a progressive manner.
Can't see it is possible on my set up, as there are no parameters that relate to this particular issue, so as I love the PAS operation, I have just learnt to live with the quirks..
 
I have a BBSHD that was custom programmed by Luna Cycles where I got it from. In my case I have very nice modulation on the throttle and I can switch between pedaling PAS and manual throttle quite smoothly. So, my guess is that whatever causes the behavior the OP is seeing is in software and can be overcome with changing the settings.

EDIT: I think this backs-up what Rassy was describing in his first reply. My BBSHD is only about 5 months old.
 
zro-1 said:
I have a BBSHD that was custom programmed by Luna Cycles where I got it from. In my case I have very nice modulation on the throttle and I can switch between pedaling PAS and manual throttle quite smoothly. So, my guess is that whatever causes the behavior the OP is seeing is in software and can be overcome with changing the settings.

EDIT: I think this backs-up what Rassy was describing in his first reply. My BBSHD is only about 5 months old.

I tried everything I could think of in the settings but could not fix the problem. It seems to be something in the firmware.
 
fechter wrote:
I tried everything I could think of in the settings but could not fix the problem. It seems to be something in the firmware.
Exactly! I did the same thing, including a conversation with Luna Cycles that consisted of 25 emails over a period of more than a month where they gave me more suggestions on things to try before they found the used controller that worked right and we swapped controllers.

I did end up with a very smooth operating BBS02B, and mastered the switch from using PAS to throttle only and back to PAS with no jerkiness. I could have just stuck with that except for a couple of things. First, I have two trikes I switch between and the other one already had a "good" controller on it and for a 77 year old dog to always remember which trike he was on was a pain. Also, just the day before I made the swap I was on one of my regular rides that includes one short but very steep hill a couple of 100 feet long. I was cruising along slowly in third gear and PAS level 2, forgot to shift down, went to throttle only, and made it up the hill, but the motor was lugged down and if I could have applied a little pedal I could have kept the motor RPMs up.

I'm still hoping to hear back from Bafang. I tried to keep my question simple just to get a confirmation about possible new firmware settings. This is the question I asked:

I have several BBS02(B) systems. Two of them with controllers dated 2016 (1605180028 and 1609270057) allow complete range of the throttle while pedaling. Two of them with controllers dated 2017 (1705310074 and 1709310074) only allow full throttle while pedaling, but allow complete range of the throttle when not pedaling. This issue applies to all PAS levels.

Is there any way to make the newer controllers operate the same as the older controllers?

They all have firmware V2.0.1.1 and the accessible variables are all set the same using a controller programming cable and PC software.
 
It seems like a major screw-up on Bafang's part if the newer versions don't work right even with the gear sensor attached.

I'm perfectly happy with disabled PAS for my uses, but I can see how most folks would want it to work as intended.
 
I have been thinking about the problem and have done a few experiments:
If I start off pedaling, and then add a bit of throttle, nothing happens until I get the throttle to a point where the throttle input is higher than what the PAS level is. Then the throttle kicks in , but it seems undecided as to whether to stick with the throttle input or the PAS input.
If I start off with throttle input only, all is smooth until I pedal faster than the throttle speed requested, and then it jumps around.

The problem seems to be that the controller doesn't know how to give either the PAS or throttle priority.
I don't know how it was handled on earlier versions of the controller?

I must say that if I had to design the control system, I'm not sure how I would do it?
If you start off with pedaling, the controller would set the amps accordingly. Then if you add a bit of throttle, does it just add a bit extra amps to the level set by the PAS, or does it take over when the throttle input is higher than the PAS level?

I actually would love to abandon the conventional throttle system and have a throttle that works as a PAS adjustment. So you just keep pedaling and hitting the throttle just moves the PAS up and up. Backing off the throttle just brings it back to the level you were at before you started the throttle movement.
This would make it much more intuitive.
Any boffin who can design a circuit?
 
The Bafang PAS system is pretty crude. The pedal sensor seems to be just on/off. It doesn't know how hard you are pedaling and as far as I could tell, doesn't care how fast the pedals are going.

What might work is to set up a throttle to change the PAS level setting. This would be the same as hitting the +/- buttons but easier to do while riding. You could then program it for 9 levels and get the levels dialed in so it gets progressively stronger and returns to the starting level when you release the throttle.
 
fechter said:
What might work is to set up a throttle to change the PAS level setting. This would be the same as hitting the +/- buttons but easier to do while riding. You could then program it for 9 levels and get the levels dialed in so it gets progressively stronger and returns to the starting level when you release the throttle.

That is exactly what I am proposing, but I have no idea how to implement this!
 
Seems like a job for an Arduino or something like that. The + and - buttons on the control are just switches, so it should be easy to interface a microcontroller to the switch wires. There's 5v there already so could be powered by that. The hardware part is fairly easy.

The software code is another story. I suck at writing code, but the first step is to define exactly how you want it to behave.

I guess another, simpler approach would be to make something that resembles a throttle but is just a switch you can tie into the existing level buttons to make changing levels easier while riding. Imagine a thumb throttle that is centered in the middle and moves both ways to increase or decrease steps. It would be easy enough to add a pulse circuit that would keep incrementing the steps if you hold it in one direction.
 
I've been toying with the idea of mounting an arduino into each pedal with a pressure switch and bluetooth module. These would then send their pressure data via bluetooth to another arduino mounted on the handlebars. This Arduino would average the pedal inputs and then map that to a PAS level (or throttle input level) to determine the amount of assist to provide based on pedal input. The programming would be fairly simple, but ironing out the details would take a while. I just really haven't had the time to jump into this project (4 little kids at home).
 
If there was a way to sense pedal pressure somewhat accurately using the existing pedals, it would make a true torque sensing PAS possible, which would be way better than the stock setup. Challenges would be making sensors in the right spot and powering the Bluetooth transmitters.
 
I have Bluetooth pressure sensors on my car tyres. Continuously send pressure and temperature to a monitor. Perhaps you can use this?
 
Interesting thought. I'll have to look into the tire pressure monitors as a source for pressure data. I was thinking more about this some more yesterday. Is there a way to disable PAS in our systems, but still have the throttle work? I'm pretty sure there is. Anyway, that would be a way to get around the issue with the throttle not working progressively while pedaling. Also I see the need for a smartphone app to enter settings from the user. For example, to set the level of assist as well as to run a calibration routine where the user pedals as hard as they can for a few seconds to establish the level of pressure at which the system will provide maximum assist.
 
I had the same problem on a BBSHD. A new controller fixed the problem. Seems like Bafang should reflash the controller with firmware that works properly. Programming won’t fix the problem.
 
I just got a new controller and it didnt fix the problem. It seems there is little way to know what to expect out of Bafangs firmware. Hence what I’m proposing is figuring out how to get around the PAS component of the firmware.
 
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