Wiring potentiometer to a PAS sensor

[cyclematt]

Hello

I’m after some advice.

My motor is a 36v 450w mid drive brushed motor without a PAS function, I’m currently using it with a thumb throttle.

I’m looking at removing the throttle and replacing with a PAS sensor.

My question is, is it possible to wire in a PAS sensor to a potentiometer and back to the controller to give me variable power control whilst peddling?

I know you can buy controllers with a PAS function but I would like to vary the output to the motor as well whilst peddling.

Thanks

 

[lnanek]

Grin Technologies' Cycle Analyst display does this. You wire the PAS sensor to the Cycle Analyst. The Cycle Analyst then has a throttle output to the controller. That throttle output gets modulated by your pedaling cadence to appear to be a regular throttle voltage range.

You can actually wire the throttle to the Cycle Analyst at the same time and use either or as you like as well. It also supports cruise control, so under certain circumstances, can send a throttle signal to the controller with you neither pedaling nor pushing the throttle.

 

[amberwolf]

My motor is a 36v 450w mid drive brushed motor without a PAS function, I’m currently using it with a thumb throttle.

I’m looking at removing the throttle and replacing with a PAS sensor.

My question is, is it possible to wire in a PAS sensor to a potentiometer and back to the controller to give me variable power control whilst peddling?

I know you can buy controllers with a PAS function but I would like to vary the output to the motor as well whilst peddling.

Without replacing the controller, the "best" way to do what you want is to use the Cycle Analyst v3.x; it takes all your inputs, controls, sensors, and processes them via your chosen settings to generate a throttle signal for your controller. It's highly customizable and does quite a few things...but it isn't cheap and it requires considerable setup and tuning for some systems to make the system do exactly what you want.

I'm using one to do what you want to do, controlling the system speed variably by how fast I pedal. You can use it to control system power instead if you like (just choose that option in throttle settings).

You can also create a device to take a cadence PAS sensor and make a throttle signal; it's been done here before:

PAS To Throttle converter using Arduino Nano

Here is my solution to convert PAS signal to Throttle input for cheap/high-power ebike controllers that doesnt have PAS input. Output power will follow pedaling speed, smoothed with a moving average logic. You might need to adjust system variables to match your motor/controller/PAS. Solder...

endless-sphere.com

Simple PAS to throttle converter using an Arduino Nano

The heading says it all. Solder according to the schematic and program the Arduino using attached program (adjust as needed, defaults work well for me). Should work instantly. You can put the Arduino Nano inside the controller case (insulate using shrinking plastic), in that case connect the...

endless-sphere.com

 

[cyclematt]

Thankyou for your feed back, I have now looked at the Cycle analyst, I can see it’s positives and negatives. I think it may be a little overkill for what I’m looking for to be honest.
In the mean time I have managed to source a speed control with a PAS sensor for not a lot of money.

Not fully understanding how it works, if I have a PAS sensor and a throttle attached at the same time (not on the some connections), can I vary the power to the PAS sensor via the throttle or would it just be full power continuous?

Thanks

 

[amberwolf]

Not fully understanding how it works, if I have a PAS sensor and a throttle attached at the same time (not on the some connections), can I vary the power to the PAS sensor via the throttle or would it just be full power continuous?

Depends on your controller's design. If it's manual doesn't tell you, you'll have to experiment to find out...but:

Almost all of them use the throttle as variable assist control (in one of a few ways), but use PAS only as an on/off (pedalling or not pedalling, regardless of cadence) control for the chosen assist level. So if your controller uses say, 3 assist levels, one set to 5mph, one to 10mph, and one to 15mph, then if you set assist level 2 and pedal, at all, it will simply try to go 10mph. If you slow your pedalling drastically, it still tries to go 10mph. If you stop pedalling, then after a few seconds, it stops trying to go at all.

The throttle would still give you variable control.

Some controllers vary between zero and the max for that assist level, some vary between zero and the max the bike is capable of under present conditions regardless of assist level.

Some controllers only allow throttle in certain assist modes, some in all of them.

Some controllers have no throttle input (and some have no PAS input).

Some controllers require you to be pedalling for the throttle to even be allowed to work. (some of these only do this below a certain speed, or above it). These are just legalization functions for certain areas around the world to comply with local regulations; there is no practical reason to require them.

If you need variable control the best kind of controller to get is a throttle-only type, and then use one of the things I previously posted to generate a throttle signal from your PAS unit's cadence output. (or a torque sensor if you prefer that, but it's a lot more complicated to setup and tune to get exactly your desired behavior, and has some potential gotchas you have to create or enable/setup safety features for unless you can be certain to avoid them).

Or something like the KT or Lishui controllers flashed with the Open Source Firmware developed in various threads here on ES, allowing you to use them with variable PAS control or throttle...keeping in mind that you'll still have to setup all the menus and settings for them to perform the way you want, pretty much like setting up a Cycle Analyst (probably a bit less complicated, though).