PAS sensor connected to wheel

[Cyclomania]

Of the cheaper PAs sensors on the market from aliekspress and so on I can only find PAs sensors that are connected to the crank and pedal axle.

Are there any of the chinese/cheap versions that are connected instead to the wheel, more like a bafang PAS sensor? I guess this would provide a more accurate speed reading so I want to hook one up to my controller.

 

[Cyclomania]

So I got this idea now. If you look at the pas sensor form Bafang below. Where the cable is cut off.

Perhaps it would be possible to solder on a male connector looking like the one below. And then hook this up to my controller connector(image 3)? What do you think?

Then I would hook it up to the wheel with a regular bafang speed magnet and perhaps it could work ?

 

[Diggs]

Are you confusing a PAS (PEDAL Assist Sensor) that must be connected to the pedals/crank with a wheel speed sensor?

 

[E-HP]

Of the cheaper PAs sensors on the market from aliekspress and so on I can only find PAs sensors that are connected to the crank and pedal axle.

Are there any of the chinese/cheap versions that are connected instead to the wheel, more like a bafang PAS sensor? I guess this would provide a more accurate speed reading so I want to hook one up to my controller.

PAS = Pedal Assist Sensor, not speed sensor.

 

[Cyclomania]

PAS = Pedal Assist Sensor, not speed sensor.

Yeah, I was thinking that how the bbs02b must be able to calculate speed has to be through the PAS sensor.
And what I need is a correct speed reading on my bike, after changing controller.

How else would the bbs02 be able to calculate speed correctly?
It has to be because the bbs02b has a magnet fastened to one of the spokes. And the sensor "feels" that magnet passing through over and over again. Which is what kicks in the PAS-sensr to do its thing.

Since my speed reading is all wrong on the new bike, despite everything else working, I think I might be able to use the PAS-sensor from a bafang kit. Since that is attached to one of the spokes. Solder on a new connector in the process.

Do you think that could work? Thing is I don't know how many magnets that sensor has but I suppose only one(?), since that magnet kicks of the Pedal assist everytime the spoke-magnet goes by the sensor.

Or would it be another way to get the correct speed reading if this is a bad idea for some reason?

 

[E-HP]

You are still confused. The PAS sensor on a BBS02 is located inside the motor housing. The Speed sensor for a BBS02 is mounted on the bikes chainstay, with a magnet mounted on a spoke.

 

[TommyCat]

Are there any of the chinese/cheap versions that are connected instead to the wheel, more like a bafang PAS sensor?

To clarify a bit…
The Bafang mid-drive pas sensor and magnets are internal to the motor assembly.
The sensor and magnet assemblies for the wheel are for speed indication only.
Googling BBS02b pas sensor assembly will bring up information that helps in identifying these two systems.

Technically they both produce a digital signal much the same way. But with a much different number of pulses do to the number of magnets that pass each one. With each output signal going to different places…


Regards,
T.C.

 

[Cyclomania]

To clarify a bit…
The Bafang mid-drive pas sensor and magnets are internal to the motor assembly.
The sensor and magnet assemblies for the wheel are for speed indication only.
Googling BBS02b pas sensor assembly will bring up information that helps in identifying these two systems.

Technically they both produce a digital signal much the same way. But with a much different number of pulses do to the number of magnets that pass each one. With each output signal going to different places…


Regards,
T.C.

Aha ok

 

[Cyclomania]

You are still confused. The PAS sensor on a BBS02 is located inside the motor housing. The Speed sensor for a BBS02 is mounted on the bikes chainstay, with a magnet mounted on a spoke.

Aha I understand a little better.

Do you think there is a way for me to use this speed sensor so that I can get an accurate speed reading on my display? Maybe to solder on this speed sensor from Bafang onto the cables of my external pas sensor mounted on the crank arm somehow?

What I am really trying to do is to get an accurate speed reading. And I was thinking this could be a way to achieve it.
If there is a better way please let me know

 

[E-HP]

Knowing what controller you have might help, otherwise no.

 

[Cyclomania]

Knowing what controller you have might help, otherwise no.

This one below. SM controller. 30a. The display is sw900.

 

[E-HP]

Post a pic of the hall connector coming out of the controller that clearly shows the conductors. It appears in the pic your posted that there may be a white wire along with the 5 wires used for the hall sensors. A white wire is frequently used for either temperature sensing or for a speed sensor, depending on the controller (and motor).
So you only have those screenshots and no links to the actual components?

 

[Cyclomania]

Post a pic of the hall connector coming out of the controller that clearly shows the conductors. It appears in the pic your posted that there may be a white wire along with the 5 wires used for the hall sensors. A white wire is frequently used for either temperature sensing or for a speed sensor, depending on the controller (and motor).
So you only have those screenshots and no links to the actual components?

Aha. I think I left that wiring untouched and I wired the halls like this finally, according to what ChatGPT and a youtube-video suggested. Then I let the self learning lines figure out the wiring( I think that is what they do). And the wiring is like this picture.

The halls are going into a drilled hole at the top, covered in silicon, that looks like the other pic here.

 

[E-HP]

You may need help from someone familiar with the SW900. I used an external speed sensor with my KT controller for a while. I connected the signal wire to the white conductor, an provided power to the sensor by splicing into the 5v and ground fron the throttle connector. I had to set the magnet parameter to 0 (or maybe 1?) so the controller would use that input rather than the motor halls. Not sure if the SW900 functions similarly.

 

[Cyclomania]

You may need help from someone familiar with the SW900. I used an external speed sensor with my KT controller for a while. I connected the signal wire to the white conductor, an provided power to the sensor by splicing into the 5v and ground fron the throttle connector. I had to set the magnet parameter to 0 (or maybe 1?) so the controller would use that input rather than the motor halls. Not sure if the SW900 functions similarly.

Cannot hurt to try. What was the speed sensor you used? You have a link possibly?

 

[E-HP]

The one for you Bbs02 should work. It will need a 5v and ground, and the signal wire would go to the white wire on the hall sensor connector as the speed input (assuming it’s a speed input and not temperature). Magnet count would be 1.

 

[Cyclomania]

The one for you Bbs02 should work. It will need a 5v and ground, and the signal wire would go to the white wire on the hall sensor connector as the speed input (assuming it’s a speed input and not temperature). Magnet count would be 1.

You mean magnet count for the PAS setting then?
Since this is a speed sensor and not a PAS-sensor maybe I do not have to write the magnet number somewhere in the display?

I am going to have a regular 12 magnet PAS sensor at the crankarm as I described before. So I guess I will set this number to 12. But the speed sensor is another one, right? I do not think it has a setting in the sw900. But maybe it could work without that setting?

 

[Cyclomania]

The one for you Bbs02 should work. It will need a 5v and ground, and the signal wire would go to the white wire on the hall sensor connector as the speed input (assuming it’s a speed input and not temperature). Magnet count would be 1.

I might to be able to hook it up for example to the throttle's ground and red right? Do you splice the cables with a connector or do you solder them onto the wire, kind of straight out of it in 90 degrees?

 

[E-HP]

If the bike is otherwise working, why not just use a gps when you need to know your speed? It’s a lot safer than experimenting or trial and error. One accidental short, and you could be buying a new controller and display.

 

[TommyCat]

I wouldn’t want to mess up a good controller ether… but it seems you are both soooooo close! Just be careful.

assuming it’s a speed input and not temperature

Can this be verified by checking resistance to ground? I.E. a speed sensors reading would not change, but the temp thermistor would change resistance with temperature… opps, that’s for checking the white wire coming out of the motor if there is one.
For the white input wire going to the controller. Perhaps checking for a 5vdc or less signal voltage that can be safely shorted to ground would be a good indicator. I.E. What a speed sensor does electrically with the signal wire/voltage.

But the speed sensor is another one, right? I do not think it has a setting in the sw900.

This manual shows that it may be, if the manufacturer supported it.

https://f.hubspotusercontent10.net/hubfs/7933366/Hub Drive Display Manual.pdf

I might to be able to hook it up for example to the throttle's ground and red right?

Or perhaps use the 5vdc and ground provided to the pas sensor, it may be easier location wise.
Update: Since your headed to the hall sensor connector anyway, you may consider it’s 5vdc and ground. I think they all come from the same source.
Keep the current use below 20mA. I.E. Keep and eye on it when connecting to be careful not to draw too much current or to catch a short quickly.

Easy does it.

Regards
T.C.

 

[Cyclomania]

If the bike is otherwise working, why not just use a gps when you need to know your speed? It’s a lot safer than experimenting or trial and error. One accidental short, and you could be buying a new controller and display.

Well the thing is that sw900 has a speed limit. And I reach that limit since I am not driving in extreme speed right now. Since it says 80km/h when I am only biking in 30km/h So it would be nice to remove that and make it show the actual speed. Then the real speed limit would also become higher.

 

[Cyclomania]

Or perhaps use the 5vdc and ground provided to the pas sensor, it may be easier location wise.
Update: Since your headed to the hall sensor connector anyway, you may consider it’s 5vdc and ground. I think they all come from the same source.
Keep the current use below 20mA. I.E. Keep and eye on it when connecting to be careful not to draw too much current or to catch a short quickly.

Easy does it.

Regards
T.C.

Yeah it is a lot of silicone around the hall sensor right now so it is probably easier to go via the PAS as you say.
Would you splice the cables with a connector? Or solder them onto there?

When would the short be most likely to occur? I was thinking I am not going to have a battery connected when I solder/connect the wires. So the short could then occur when I hook everything up to the battery?

 

[Cyclomania]

If the bike is otherwise working, why not just use a gps when you need to know your speed? It’s a lot safer than experimenting or trial and error. One accidental short, and you could be buying a new controller and display.

When are the shorts most likely to occur? I am thinking about splicing the cables in three kind of like he does in this video:

That could work right? I mean when I solder onto the PAS sensor's ground and red from the speed sensor's ground and red.

 

[E-HP]

Looks ridiculous. He skipped the step of insulating the connection, which will turn into a big glob of electrical tape.

 

[beemac]

I use a method similar to this - except I wouldn't remove so much insulation and wrap so many times. I would also solder the joint after wire wrapping. Always remember to put the heatshrink over first - I dread to think the number of times I've done a load and forgotten to put heatshrink on the last one and had to unpick and redo!

Get the most 'shrinking' heatshrink you can - 3x better than 2x etc. as it means you can wrap a wider variety of wire thicknesses and still get a tight fit. If you buy red and black heatshrink get at least twice as much black since you use it a lot more or just don't bother buying red...

another good tip if you're splicing a number of wires bound together somehow - e.g. a multicore cable - don't cut all the individual wires in the same place. Stagger the cuts so if the insulation does wear off or get damaged they are less likely to short as all the joins aren't next to each other. This also means when you wrap the final joined multicore there isn't so much of a bulge.

Oh I hadn't realised you were asking specifically about joining three wires - tbh just do the same but twist two of the wires together first - then do as the video above. that will give you more of a Y connection - and that works better with heatshrink. Think about which direction you want each wire to go afterwards to help with cable routing.