Reporting Battery Level

  • How to add to sketch this feature? I use Domoticz controller and serial gateway. Nodes is Arduino mini pro 3,3V with batteries. Today i use door open/close sensor, elecricity meter, moisture sensor.

  • I don't have my sketch available, but I used this code below for measuring 2xAA. I have changed #define MIN_V 1900 (milliVolt) since I have disabled BOD, so Arduino runs to 1,8V, bur NRF24L01+ is working down t0 1,9V
    NOTE: This is only showing battery measuring, it's not a full sketch...

      void loop() 
      #define MIN_V 2700
      #define MAX_V 3200
      int batteryPcnt = min(map(readVcc(), MIN_V, MAX_V, 0, 100), 100); // Convert voltage to percentage
      gw.sendBatteryLevel(batteryPcnt); // Send battery percentage to gateway
      long readVcc() {
        // Read 1.1V reference against AVcc
        // set the reference to Vcc and the measurement to the internal 1.1V reference
        #if defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
          ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
        #elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
          ADMUX = _BV(MUX5) | _BV(MUX0);
        #elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
          ADMUX = _BV(MUX3) | _BV(MUX2);
          ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
        delay(2); // Wait for Vref to settle
        ADCSRA |= _BV(ADSC); // Start conversion
        while (bit_is_set(ADCSRA,ADSC)); // measuring
        uint8_t low  = ADCL; // must read ADCL first - it then locks ADCH  
        uint8_t high = ADCH; // unlocks both
        long result = (high<<8) | low;
        result = 1125300L / result; // Calculate Vcc (in mV); 1125300 = 1.1*1023*1000
        return result; // Vcc in millivolts

  • Okay. I understand but how to add this piece from software to each sketch? Each what arduino powerted from batteryes.

  • Hero Member

    @Fat-Fly Easiest way is to use the Vcc library by @Yveaux

  • This is better. I need cut off Arduino voltage regulator and power led ?

  • Hero Member

    @Fat-Fly To save power you can... but not needed for the Vcc library to work if you power your pro-mini from the vcc pin 😉

  • Ok. I try to write sketch.

  •  * The MySensors Arduino library handles the wireless radio link and protocol
     * between your home built sensors/actuators and HA controller of choice.
     * The sensors forms a self healing radio network with optional repeaters. Each
     * repeater and gateway builds a routing tables in EEPROM which keeps track of the
     * network topology allowing messages to be routed to nodes.
     * Created by Henrik Ekblad <>
     * Copyright (C) 2013-2015 Sensnology AB
     * Full contributor list:
     * Documentation:
     * Support Forum:
     * This program is free software; you can redistribute it and/or
     * modify it under the terms of the GNU General Public License
     * version 2 as published by the Free Software Foundation.
     * Simple binary switch example 
     * Connect button or door/window reed switch between 
     * digitial I/O pin 3 (BUTTON_PIN below) and GND.
    #include <MySensor.h>
    #include <SPI.h>
    #include <Bounce2.h>
    #include <Vcc.h>
    #define CHILD_ID 3
    #define BUTTON_PIN  3  // Arduino Digital I/O pin for button/reed switch
    MySensor gw;
    Bounce debouncer = Bounce(); 
    int oldValue=-1;
    // Change to V_LIGHT if you use S_LIGHT in presentation below
    MyMessage msg(CHILD_ID,V_TRIPPED);
    //battery voltage
    const float VccExpected   = 3.0;
    const float VccCorrection = 2.860/2.92;  // Measured Vcc by multimeter divided by reported Vcc
    Vcc vcc(VccCorrection);
    static int oldBatteryPcnt = 0;
    void setup()  
     // Setup the button
      // Activate internal pull-up
      // After setting up the button, setup debouncer
      // Register binary input sensor to gw (they will be created as child devices)
      // You can use S_DOOR, S_MOTION or S_LIGHT here depending on your usage. 
      // If S_LIGHT is used, remember to update variable type you send in. See "msg" above.
      gw.present(CHILD_ID, S_DOOR);  
    //  Check if digital input has changed and send in new value
    void loop() 
      // Get the update value
      int value =;
      if (value != oldValue) {
         // Send in the new value
         gw.send(msg.set(value==HIGH ? 1 : 0));
         oldValue = value;
        int batteryPcnt = (int)vcc.Read_Perc(VccExpected);
        if (oldBatteryPcnt != batteryPcnt)
            oldBatteryPcnt = batteryPcnt;

  • Verification successful says codebender. I do not know working this or not. I can't try. Only in home after working day.

  • This is modified electricity meter sketch with battery level .

  • @Fat-Fly Nice, interested to try this also.
    Any idea how long the batteries will last? Electricity meters tend to blink quite often, so not that much sleep..

  • At the moment i try this with 2xAA recargeable batteryes but no luck. Gnd and vcc pin. Not working , not reported. if i find batterys.... I search. All remotes is AAA 😞 2.68volts from recargeable AA's. where is the fish ?

  • From recargeable 2x AA and 2,68V not working.

  • I bought 2AA batteries. Working.Domoticz devices page report battery level 3. How to see battery level graph ?

  • Hero Member

    @Fat-Fly to report battery voltage you have to create a S_MULTIMETER sensor and send the voltage with V_VOLTAGE.

    Sendbatterylevel only changes the battery level in Domoticz in % and can not be shown separate.

    Tot use your arduino with low voltages you need to change the fuse settings (BOD) with an ISP programmer.

  • How to i do this ?

  • Hero Member

    @Fat-Fly I will post some code later when I get to a pc. 👀

  • @AWI said:

    @Fat-Fly I will post some code later when I get to a pc. 👀

    This is great. I do not find from google search. My mother tongue is Estonian 🙂

  • Hero Member

    @Fat-Fly "Estonia: Between East, West and the World" 😉

    These are the lines of code which should do the trick... you need to put them in the right spot yourself

    #define VOLTAGE_CHILD_ID 		5
    MyMessage voltageMsg(VOLTAGE_CHILD_ID, V_VOLTAGE);	// Node voltage
    gw.present(VOLTAGE_CHILD_ID, S_MULTIMETER, "Battery " );
    float voltage = vcc.Read_Volts() ;
    gw.send(voltageMsg.set(voltage,2));				//send battery in Volt 

  • Estonia between world and russia. 🙂

  • @Fat-Fly I am not sure how you intend to arrange your electricity pulse meter reading, but in my case I had to wire Pro Mini 5V to mains or otherwise recharge a battery every 5-7 days. I think you can do the total kWh and putting Pro Mini to sleep, but you cannot have total consumption kWh and current consumption kW with sleeping.

  • Yesterday this not working. KW reader is too away from gateway.My house is lenght is 22m. Electricity meter is one end of house and gateway is center house. can i use repeater on something other. I use for this nrf with antenna.

  • Mod

    @Fat-Fly check the "range issues" troubleshooting flowchart at

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