Can I tap in the PAS wire and add a resistor or pot?

[TypeThree]

I'm building up a super cheap little 250 watt commuter setup with a Conhis front motor and controller.

It is a pretty rudimentary setup and the PAS crank sensor appears to act like a full throttle switch. I don't really like that it goes full throttle with crank movement, would prefer to set it lower and then use the twist grip throttle for any additional throttle.
My question:
Is there a cheap and simple way of tapping the PAS wire with a resistor and limiting the throttle to say 1/2 throttle or add in an adjustable pot? I want to set and forget it without having to run more wires and switches on the handlebars or changing controllers. The controller as I said is quite rudimentary so it has no port for a PAS speed or cruise control. The wire from the controller has the same 3 pin plug and same three coloured wires as the throttle. I believe they might be interchangeable since they were not labelled.

 

[amberwolf]

There are a few threads about how PAS can work; you'd need to test yours for whcih of those ways it actually does before you'd know which way to limit the output of the controller during operation.

(or just try the experiments)


The most likely way yours works is just a pulse output as the magnets on the ring pass the sensor, so a resistor or pot will probably only make it not work at all below some threshold, and otherwise just work like it does now.

To change the speed output of your existing controller in those cases, you'd need to program it, either via a USB or serial port with the correct software for that specific controller, or else use the appropriate LCD display made for use with that controller (if it is capable of using one).

I don't know how to tell what you'd need for either of those, or even if it's possible to do so with your controller, but you could open it up and search ES for the numbers marked or etched on the corner/edge of the PCB; there might already be a thread about it.

 

[flangefrog]

No. The PAS device works differently than a throttle - instead of an analog output it gives a certain number of pulses per revolution of the cranks. If the controller senses how fast you're pedalling and changes the motor speed you could install a PAS sensor with a different amount of magnets or remove some magnets from your existing one. This will give less pulses per revolution and to the controller it would look like you are pedalling slower.

 

[TypeThree]

It appears to just be on or off with movement without any modulation in between. It's not smart enough to see slow pedaling and adjust the throttle accordingly.
I've read elsewhere if I remove magnets I'll just increase the initial start-up delay.
I might have to bust out the multimeter and see what exactly happens in that signal wire when the crank turns.

 

[d8veh]

It appears to just be on or off with movement without any modulation in between. It's not smart enough to see slow pedaling and adjust the throttle accordingly.
I've read elsewhere if I remove magnets I'll just increase the initial start-up delay.
I might have to bust out the multimeter and see what exactly happens in that signal wire when the crank turns.

That's right. It's only a few controllers that respond to pedal speed. I wouldn't recommend one that works like that. It sounds like a logical control idea, but in practice, it's diabolical.

To solve your problem, a new controller will give you the ability to select different power levels from a LCD or LED panel. One like that will cost about $100 with LCD, speed sensor, PAS and shipping; or about $50 for a three-level LED one.

What motor do you have and how many amps is your present controller (written on the label)?

 

[TypeThree]

Thanks for the replies.
Its a relatively inexpensive conhis motor and controller. Originally 200w 24v system. I'm running 8 cell so 29.6 v. Doing the math I must be around 250w and approx 8-10a continuous. I built one the same prior to this bike on an old Chromoly GT and my friend just had to have it so I sold it. That one is running fine but I didn't install the PAS sensor.

Regarding alternate controllers, I have a nice Lyen 6 fet controller for my next build which would do the job I want but for this current bike I really do want to keep the controller it came with. I set myself a tight budget for this one because I'm just gaining experience and not sure if it's going to be a keeper. I have too many bikes so the dollars are always adding up even if individual expenses don't sound like a lot.

I think considering the answer to my question has so far been something like "not without significant changes" I'll probably disconnect the PAS or put a switch in the line to disable it. It just feels too awkward to accelerate with full assist whenever the cranks spin. Might have to head toward installing a torque sensor for the next build.

 

[gwhy!1]

Something you could try... I have not done this myself but it may work : is fit a rc filter on the output of the pas sensor ( very cheap , as its just a resistor and a small capacitor ) then feed it into the throttle input. this will create a 0-5v output depending on how fast the cranks are spinning, you will have to play with the rc values to get your desired throttle response and you may also have to setup a 0.8v offset at 0v so the controller thinks it has a throttle connected but its worth playing with.

the signal wire from the pas should just be pulsed 0-5v and the frequency of the pulses will depend on speed of rotation.

 

[Htfan]

Something else to try is a "voltage" PAS sensor that replaces the traditional pulse sensor. I purchased one from Lyen for my installation. Can't remember the price but it was somewhere around $20. It provides 0 to 5v based on pedal speed and looks and mounts just like any other PAS sensor.

The main difference is it acts like a second throttle. (It is actually spliced into throttle wires.) I also added a 5k pot inline for full control.

May not be "better" than replacing the entire controller, adding an LCD or CA3, but much easier on the wallet until I decide to spend the $$$ on those things.

Just my 2 cents...

 

[TypeThree]

Something else to try is a "voltage" PAS sensor that replaces the traditional pulse sensor. I purchased one from Lyen for my installation. Can't remember the price but it was somewhere around $20. It provides 0 to 5v based on pedal speed and looks and mounts just like any other PAS sensor.

The main difference is it acts like a second throttle. (It is actually spliced into throttle wires.) I also added a 5k pot inline for full control.

May not be "better" than replacing the entire controller, adding an LCD or CA3, but much easier on the wallet until I decide to spend the $$$ on those things.

Just my 2 cents...

Something you could try... I have not done this myself but it may work : is fit a rc filter on the output of the pas sensor ( very cheap , as its just a resistor and a small capacitor ) then feed it into the throttle input. this will create a 0-5v output depending on how fast the cranks are spinning, you will have to play with the rc values to get your desired throttle response and you may also have to setup a 0.8v offset at 0v so the controller thinks it has a throttle connected but its worth playing with.

the signal wire from the pas should just be pulsed 0-5v and the frequency of the pulses will depend on speed of rotation.

Thanks for both of those suggestions. The RC filter is a cool idea and the existence of a voltage type PAS sensor is news to me. I'm going to have to test my PAS sensors now since there is a fair chance it's already voltage based. I checked out this thread https://endless-sphere.com/forums/viewtopic.php?f=2&t=22686#p330421 and found that the voltage type sensor looks a lot like mine in size but not exact. I'm actually quite happy there's a couple of options to try out. I might just have to order one of those PAS sensors from Edward if mine turns out to be the pulse type.

 

[TypeThree]

So here's the type I have on the bike, it has the same red green black wires and plug as the throttle cable. I suspected all along that it runs parallel inside the controller which led me to ask the question at the beginning of this thread but not entirely sure until I open up the controller.




Checking my bundle of goodies I got from Edward last month for my next project I got a mini monster controller and also bought a PAS sensor which upon looking at it I think it's the voltage type explained earlier. Since I bought the Controller with the plugs for Cycle Analyst I expect Edward would have included the voltage type PAS to suit plugging into Cycle Analyst. Can anyone confirm by looking at the pic? It says V series so I assume that V is short for Voltage.

 

[docw009]

You can easily test that sensor with a meter to find out if it's an analog signal. If not, there are inexpensive voltage mode sensors on ebay, but it might take a few weeks to ship and I wonder how well they work.

http://www.ebay.com/itm/Electric-Bike-Power-Pedal-Assist-Sensor-PAS-Voltage-Mode-EBike-Assistant-KIT-/231655274372?hash=item35efbaf784:g:hiAAAOSw9N1V0AMQ

 

[amberwolf]

FWIW, that one looks exactly like the one on my Fusin kit, which is a pulse-type, but you'll need to check yours to be sure.

 

[d8veh]

Don't waste any more money on anything other than a controller that's properly designed for PAS function, like the Kunteng ones that are readily available from a number of sources, and probably available locally.

You don't need a torque sensor. A normal PAS sensor will satisfy you with the right controller. It's a shame you got a Lyen controller instead of a KT. A Lyen is a good controller, but not for PAS unless you want to buy other expensive accessories like a CAv3 and/or a torque sensor.

Converting your PAS signal into a throttle signal will not be satisfying on your bike. Trust me!.

 

[TypeThree]

Don't waste any more money on anything other than a controller that's properly designed for PAS function, like the Kunteng ones that are readily available from a number of sources, and probably available locally.

You don't need a torque sensor. A normal PAS sensor will satisfy you with the right controller. It's a shame you got a Lyen controller instead of a KT. A Lyen is a good controller, but not for PAS unless you want to buy other expensive accessories like a CAv3 and/or a torque sensor.

Converting your PAS signal into a throttle signal will not be satisfying on your bike. Trust me!.

Thanks for your input d8veh. I checked out those controllers you mentioned and I noticed they had two model lines. One was Sine wave and the other line said square wave with some kind of torque sensor simulation programming. Any guidance on those would be appreciated.
For the moment I'm running without PAS but I would like to pick up (if not too expensive) a better controller to run it at some point preferably something with an adjustable LVC for 8 cell and something to smooth out the vibration I'm getting during acceleration. it's clearly a motor phase type of vibration not a bearing or oscillating/bent shaft type of thing. I'm assuming that has something to do with it not being sine wave but I'm just a noob at ebike controllers so it could be something else. I'm guessing with hard tire pressure on commuter style bikes having a smoother power delivery is a lot more noticeable.

 

[d8veh]

The S06S is a sinewave controller that's smoother and quieter than the squarewave S06p. The S06S only works with hall sensor motors. The S06P can work with either sendored or sensorless.

"Torque simulation" means current control, where each PAS level is a current level. Other controllers use speed control, where each level relates to a taget speed. The S06S/P can be switched between the two modes