How do basic LED display's interact with controller?

[Digerido]

Hi,
I've got this stock, basic 36v 250w e-bike that I am making into something more fun just because I enjoy tinkering. So I am thinking of adding a Cycleanalyst V3 and a second hub motor to go 2wd. I've got some things figured out but need some help on this (and other stuff eventually :wink: ).

The stock LED-display is used to turn the bike on/off, change assist level, turn lights on/off, and show SOC. The connector is 5 pin. I don't want to use this LED-display, but how do I turn the controller on without it? Could it be so simple that those 5 pins are:
5v
Ground
Output to controller for e-bike on/off
Output to controller for lights on/off
Output to controller for assist level
And the SOC is just, I don't know, magic? :lol: Or maybe the e-bike on/off and assist level are on the same pin which leaves one pin for SOC.

 

[E-HP]

Hi,
I've got this stock, basic 36v 250w e-bike that I am making into something more fun just because I enjoy tinkering. So I am thinking of adding a Cycleanalyst V3 and a second hub motor to go 2wd.
The stock LED-display is used to turn the bike on/off, change assist level, turn lights on/off, and show SOC. The connector is 5 pin. I don't want to use this LED-display, but how do I turn the controller on without it?

You should leave the stock "display" as-is. No need to remove it if it works. The CA will be an add on, but your overall power output limit will be from your existing assist setting from your display, and the CA will manipulate it from there.

Questions:
Do you currently have a throttle, PAS, both?

The cycle analyst 3 doesn't interact with your controller, except as the throttle input. For controllers that have a CA dedicated connector, it's simply doing the same function as the version of with the external shunt and throttle pass through from the link below, which is the right one for you, unless you're upgrading your controller with one that has a CA connector.

The CA needs inputs for battery level voltage, a current sensing input (from the shunt), and a speed input signal (from one of the hall wires from the motor, or from an external speed sensor), in order to function. The other inputs are for throttle, PAS sensor, and brake cutoffs. You can wire other auxiliary inputs/switches/potentiometers as well, depending on what functions you are using. The output is a throttle signal going to the controller.

https://ebikes.ca/shop/electric-bicycle-parts/cycle-analysts/ca-sa.html

The other route to go is to add a CA connector to your controller. If you are handy with a soldering iron, you could do that and use the normal CA 3 and not add an external shunt, although I'd recommend the version with an external speed sensor since you said your bike is 250W, which typically indicates a gear motor. A geared motor won't have a hall signal when coasting, so if the CA is using a hall signal to determine speed, the display will show 0 when coasting. An external speed sensor solves that issue, if it matters to you.

 

[docw009]

Two possibilities:

A< Anakog - Only a few basic functions.
1, Battery Power
2. Ground
3, Ignition - signal goes toe battery power when device is turned on
4. SIgnal
1V = PAS 1
2V = PAS 2
3V = PAS 3
4V = walk mode
5. Light signak

B, Digital - Device is capable off sending commends to controller and receiving data
1, Battery oiwer
2, Ground
3. Ignition - same as above
4. Serial Data in
5. Serial Data out

I have 810LED displays that are either 4 pin and analog with no lights, or 5 pin and digital.

 

[Digerido]

Questions:
Do you currently have a throttle, PAS, both?

I have both.
I'd like to remove the display to try and keep things neat. Looking at docw009's post, seems like I should be able to add a jumper cable so that the controller starts when I turn the battery on (there's a on/off key switch in the battery). And then I'll just wire the lights separate from the controller.

Yes, I was thinking CA V3 with external shunt and external speed sensor. Seems that's the way to go if using two controllers and two motors. I'll plug throttle, PAS and brakes into CA.

Is there a way to tell if my hub motor is geared or not? It's quite small, so I'm guessing geared??

My real concern is my battery. Will it be powerful enough for two 250W motors? I mean I know it's not Battery is 36V, ~400Wh and is labelled "Max discharge current 18A". Problem is both controllers are continuous 7A and peak 15A. 15+15=30 and that's a lot more than 18. And motors are probably continuous 250W but with a higher peak. The sensible solution is to get a beefier battery or maybe running two batterys even. But I figure I'm gonna try this first with the battery I have and having the CA limit the current. Some trial and error is almost always good (and maybe expensive) fun :lol:

Please, share your thoughts. This is all for fun.

 

[E-HP]

My real concern is my battery. Will it be powerful enough for two 250W motors? I mean I know it's not Battery is 36V, ~400Wh and is labelled "Max discharge current 18A". Problem is both controllers are continuous 7A and peak 15A. 15+15=30 and that's a lot more than 18. And motors are probably continuous 250W but with a higher peak. The sensible solution is to get a beefier battery or maybe running two batterys even. But I figure I'm gonna try this first with the battery I have and having the CA limit the current.

The CA can limit the power or limit the current, so you can use that to avoid destroying your battery until you buy one that's more capable.

 

[Digerido]

I finally managed to figure this out and though I'd share.

I was able to start the controller with a jumper cable. I found the correct pins to connect by opening the LED display on the handlebars ( This destroyed the glue-like water seal). There I could see where the cables from the controller connected. Using a simple volt meter and the function that beeps when there is conductivity I found out which one was earth. Measuring voltage I found which one was positive from the battery (about 40 volts when the bike is switched off). These two were also labelled "VCC" and "GND" so that helped 8) Then I had three more pins that were not labelled in any way that helped me. So I turned the bike on using the LED display as I usually do and measured the pins. One of them was now also 40 volts (the one labelled "K"). The other two where between 0 and 5 volts depending on PAS setting and if the lights were on. I guessed that sending 40 volts on that pin that got 40 volts after the bike was turned on was the way to start it.
Finding out which pins in the cable connector was positive from battery and the start signal was easy with the volt meter and beeper function, measuring in the connector and in the LED display. Then I simply inserted a little jumper cable and then the bike was turned on.
This way the bike will automatically start when I turn the key on the battery. However I'm unable to adjust PAS level, it is always max. This is not a problem for me because I plan to do PAS via an Arduino later on. I can't control the lights either but I simply connected them to the switch on the battery so they are always on with the bike.

Whats the point you may ask. Well I'm building a 2wd bike but I don't want to have two LED displays on the handlebars. This was just one step one that 2wd journey

 

[docw009]

It was probably not clear in my earlier post, but PAS control is analog with that unit. On the 810LED, 1V is PAS 1, 2V is PAS 2, 3V is PAS3, and 4 V is walk mode. I suppose default is PAS3 when you have the display bypassed. You can experiment with a resistor bridge, maybe get your Arduino to apply different voltages later,.

You figured out the start procedure. I think most displays, even the LCD models, raise the equialent of the K lead to battery level to start the controller. On my controllers, that lead goes directly to a DC-DC converter that puts out the 15V to run the motor control. And there is a second converted to drop 15V down to 5V.

 

[ANI]

you have absolutely decoded it correctly, I just followed your steps and it gave me results.
I shorted Vcc and K after tracing them, the bicycle started working. Great job by you