Battery Level adjustment

[Emmpunkt]

Is it possible to adjust the battery level?
My Heltec V3 shows 71% when the battery is fully charged (4.176V)
Thanks M.

[liamcottle]

Battery percentage is calculated in the web client and mobile client, the firmware only provides the voltage.

At this stage, the calculation is linear, and I didn't put too much time into tuning it. We can probably add some sort of table based on different boards, but for now, this is the currently calculation code:

class BatteryUtil {

  static int getBatteryPercentage(int millivolts) {

    const minVoltage = 3400; // show battery as 0% at or below this value
    const maxVoltage = 4200; // show battery as 100% at or above this value

    // 0% if at or below min voltage
    if(millivolts <= minVoltage){
      return 0;
    }

    // 100% if at or above max voltage
    if(millivolts >= maxVoltage){
      return 100;
    }

    // linear calculation
    // todo implement curve based voltage to percentage calculations
    return (((millivolts - minVoltage) / (maxVoltage - minVoltage)) * 100).floor();

  }

}

[Emmpunkt]

Thanks for the answer,
but i don´t think that this is the reason.
I think the value from the Heltec is wrong and needs adjusting.
Even with USB connected and full battery it does not show more then 71%.
Can i check the voltage comming from the Heltec somewhere? CLI?

[recrof]

@Emmpunkt you can check it here: https://liamcottle.github.io/meshcore.js/ (connect and choose GetBatteryVoltage button)

[Emmpunkt]

OK,
Battery voltage measured : 3744mV (Kaiweets HT206D)
Voltage by the device : 3552mV (16%)

[deadphyre]

I just wanted to comment on here as I'm using meshcore on the same device and also see that it does not go above 71%. Not that this helps any but does confirm Emmpunkt's discovery.

[recrof]

Heltec_v3_companion_radio_ble-dev-merged.bin.zip please try this firmware - it has alternative voltage retrieval routine.

[Emmpunkt]

@recrof Battery is now at 0mV and 0% ;)

[Emmpunkt]

Can someone please change Line 96 in HeltecV3Board.h
from:
return (5.2 * (3.3 / 1024.0) * raw) * 1000;
to:
return (5.42 * (3.3 / 1024.0) * raw) * 1000;

I found the number in the Heltec Forum...
Thanks M.

[recrof]

Can someone please change Line 96 in HeltecV3Board.h from: return (5.2 * (3.3 / 1024.0) * raw) * 1000; to: return (5.42 * (3.3 / 1024.0) * raw) * 1000;

I found the number in the Heltec Forum... Thanks M.

you can open PR if you believe those are accurate for all V3s.

[Emmpunkt]

I´m not a programmer, i´m (industrial) electrician.
It would be better if the value is adjustable because it depends on 2 resistors with unknown quality.
In my case the 5.42 is way better then the 5.2, but there is still room for more accuracy...

[446564]

I´m not a programmer, i´m (industrial) electrician. It would be better if the value is adjustable because it depends on 2 resistors with unknown quality. In my case the 5.42 is way better then the 5.2, but there is still room for more accuracy...

Please try this firmware and report back so I can open a PR. After #413 the percentage accuracy will improve further.

Heltec_v3_companion_radio_ble.zip

[Emmpunkt]

At least it killed my config.... And i don´t have a Backup...
I have to charge my battery first to tell more.

[446564]

At least it killed my config.... And i don´t have a Backup... I have to charge my battery first to tell more.

Apologies for that 😢

[Emmpunkt]

Seems to work. App voltage versus measured voltage was 0.01V difference.