Calibrating the Cyclotricity Stealth LCD battery level.

[PH001]

So, after having the Stealth for 18 months or so I concur with most people in that the battery level on the LCD is complete gash and is certainly at odds with the LED indication on the battery pack itself. I'd like to make it more accurate.

I was looking at the motor parameters which you can get into via the LCD controller and noticed that P5 is the setting for power monitoring mode.... link

I think by default from Cyclotricity it is set to 'smart' mode:
P5=15 (48V, 1000W bikes) and P5=12 (36V, 500W bikes).

This is in contrast to P5=0 which is just real time voltage monitoring mode. This begs the following questions:

1) Has anybody tried P5=0 to run it in real time voltage monitoring mode?

2) With P5<>0, the battery is monitored in 'smart' mode. But what exactly is this and how is it measured?

3) The main issue with the LCD display seems to be that it shows the battery as empty long before the LED indication has even dropped 1 bar! So, on the basis that P5=15 is for 48V scaling and P5=12 is for 36V scaling, it stands to reason that if we drop the P5 value by say 1 point that the LCD will give an increased indication of battery level and perhaps something more consistent with the LED battery indication.

4) Can anybody confirm what is actually responsible for the battery cutoff when discharged. Is it the LCD controller or the BMS in the battery?

5) What voltages for a 48V battery would you consider fully charged, 50% charged and discharged?

 

[Deleted member 4366]

It's a simple damping factor. the higher the number, the more the response is damped. You can set it to whatever you want, but I've always found the default values OK. The default for 48v is 12 IIRC.

 

[PH001]

Thanks d8veh. I wonder why they would set a different damping factor for a 36V system compared to a 48V? If it's not for scaling then I guess it just auto detects the nominal battery voltage then?

Would you be able to shed any light on questions 4 & 5?

 

[Deleted member 4366]

It's like a moving average calculation. The bigger the number, the longer the time period it takes to calculate the average over, so it slows down the response. When set to zero, the time period is zero, so its response is instant.

 

[PH001]

Is it the LCD controller that cuts the power when it thinks the battery is depleted or does the BMS in the battery do that?

 

[anotherkiwi]

The LVC is in the controller which turns off when the voltage reaches a certain level.

the default value is 3v per cell string so 30v for a 36v battery and 40v for a 48v battery.

 

[PH001]

The LVC is in the controller which turns off when the voltage reaches a certain level.

Thanks! I guess the one in the BMS is just there as a backup measure for parasitic draw then.

Hmmm, I think I will have a play around with this P5 value and see what the effects are. I'm wondering if it is set to pure voltage mode that it could trip the motor prematurely when seeing big current demands that result in volt drops.

I'd also like to see how slewed it is when set to maximum value (40). The downside being there could be a very big delay in getting a 'full' reading after recharging.

 

[anotherkiwi]

This is one of the differences I have with d8veh: I prefer the real time voltage display so my controllers are all set to P=0.

As soon as the controller detects a real voltage lower than than the LVC it turns off. If it is the result of voltage sag it will work again as soon as battery voltage rises to above LVC.

The default value isn't the maximum value, you can set that from -1.5v to +1.5v in 0.5v steps in the C parameter 12.

The LVC in the BMS serves as a backup to the LVC in the controller, I wouldn't rely on it personally.

 

[Deleted member 4366]

There's a voltage divider on the controller's PCB that its processor uses to see the battery voltage. The LCD has something similar and it reads the divider as an input to its CPU. I'm pretty sure that it sends some info to the controller about battery voltage and it can tell the controller to switch off in some circumstances, like when you've set the wrong voltage or it thinks you have a 48v battery when you actually have a 36v one. None of that should be affected by P5.

Don't forget that you can run the controller without the LCD.