Need help configuring CA3

[philrock]

Greetings - I'm new to the forum and also new to e-vehicles. I'm converting a go-kart from gas to electric. I've bought a CA3-DPS. I would like the CA to show (among other things) vehicle MPH and motor RPM. The motor will drive the go-kart rear axle through a timing belt: 42 teeth on the motor pulley, 63 teeth on the axle pulley. I've mocked up the CA system using a drill press instead of the go-kart motor. I'm sensing the speed of the drill press spindle and feeding it into the Sp wire of the CA. The CA is showing correct vehicle MPH for the wheel size I've input, with the AXLE running at the speed it's reading, AND the CA is showing 0.0 RPM!! How do I get the CA to show the RPM it's reading on the Sp wire? How do I get the MPH corrected for the drive ratio?

I know all the math for calculating vehicle speed from motor speed, pulley teeth, and wheel size. What I need help with is how to configure the CA to show what I want as stated above. I have a feeling I need to change some PAS parameters, but I don't know which ones. Also, I have no idea what most of the parameters mean - I don't even know what PAS stands for - Pedal Assist?

I've downloaded and printed out the Endless Sphere Un-Official guide.

I've downloaded the CA software for Windows, but do not yet have the USB cable to connect the computer to the CA.

I'm stuck - any help you can provide would be greatly appreciated.

Phil Rockwell

 

[amberwolf]

I would like the CA to show (among other things) vehicle MPH and motor RPM.

You can use the speed sensor input for reading the MPH (wheel speed), but there isn't a dedicated RPM input.

The PAS input pin for a cadence sensor (rather htan the torque sensor pins) may be able to be used to read a pulse-train (squarewave) tachometer signal from the motor, but I don't know what the value limit is (how many RPM it can read; how fast a signal, since it's intended to detect pedal input). It can be set to various numbers of poles, which in a mangnetic switch sensor is how many magnets are on the rotating "wheel" of the RPM sensor. If you use a hall sensor on the motor then the number of poles is whatever the motor's number of poles is.

I dont' know if there is any way to display both MPH and RPM on the same screen, though.

How do I get the CA to show the RPM it's reading on the Sp wire?

It doesn't display the RPM of the SP wire. AFAIK that's only displayed in the MPH/KPH field.

THe only RPM displayed is of the PAS, showing human pedalling cadence.

I *think* either Justin_LE or Teklektik has shown how to use the PAS input to monitor motor RPM somewhere in teh CAv3 beta thread; it may be listed in Teklektik's index post there. Can't remember.


If you don't want any limiting or engagement to occur based on this input, don't connect the throttle output of the CA to your controller (just hook up your throttle directly). If you do need limiting to occur but not based on the PAS input, just disable the PAS control (it'll still read/display the RPM).

How do I get the MPH corrected for the drive ratio?

The easiest way (which it sounds like you're doing via the drill press simulation) is to use a sensor on the actual wheel, or on the wheel's drive axle directly, so you don't have to deal with that. If it's a single trigger (magnet, etc) on the wheel/axle, then use 1 for the number of poles. Otherwise use however many magnets (etc) you used on the wheel/axle. Then input the actual tire/wheel diameter in mm, and calculations are automatic.

Otherwise, you could use the number of poles setting to get a ratio, as it will divide the input pulses by the number you use there, then calculate it's speed based on whatever you put into the wheel size. But I don't know *exactly* what you'd need to setup in the CA for that.




You dont' need the app or USB cable to setup the CA, though it's easier to do in teh cmputer with all the values right in front of you, instead of buttoning thru the menus on teh device itself. Plus you can save as many different versions of the settings as you like.

 

[philrock]

amberwolf - thanks very much for your thorough reply. After re-reading your reply and the Unofficial User Guide many times, I finally discovered that there is a separate input for RPM - the pin 4 yellow wire on the 5-pin Torque/PAS connector. It looks like I'll use the
SP input for axle speed (and hence vehicle MPH) and the RPM input for motor speed.

Now I just have to figure out how to drive and configure the RPM input.

Thanks again for your help.

Phil Rockwell