Arduino UNO Lithium Battery Charge Indicator - Extended Example

This example demonstrates how to estimate the charge level of a lithium-ion battery using an Arduino UNO. The code calculates the battery charge level based on the voltage reading and estimates the remaining discharge time based on a given battery capacity in Watt-hours (Wh) and a discharge load.

Detailed Steps

Arduino Code


/*
 * Arduino UNO Lithium Battery Charge Indicator
 * Measures battery voltage and estimates charge level and discharge time.
 * Capacity parameter in Watt-hours (Wh) and discharge load based on 10% of Wh rating.
 * © 2024 Copyright Peter I. Dunne, all rights reserved
 * Prepared for educational use
  * Released under the Mozilla Public License
 */

const int batteryPin = A0;      // Battery voltage connected to A0
const float adcMaxVoltage = 5.0; // Maximum ADC voltage (5V)
const float maxADCValue = 1023.0; // Maximum ADC value (10-bit resolution)

// Battery parameters
const float batteryCapacityWh = 2.0; // Battery capacity in Watt-hours (example: 2.0 Wh)
const float dischargeLoadFactor = 0.20; // Discharge load is 10% of battery capacity

void setup() {
    Serial.begin(115200);  // Start serial communication
}

void loop() {
    // Read battery voltage from ADC
    float batteryVoltage = analogRead(batteryPin) * (adcMaxVoltage / maxADCValue);

    // Convert voltage to charge level percentage (assuming linear relationship)
    // Example calibration factors may be needed for accurate readings
    float minVoltage = 3.0;  // Minimum voltage of battery (fully discharged)
    float maxVoltage = 4.2;  // Maximum voltage of battery (fully charged)
    float chargeLevel = ((batteryVoltage - minVoltage) / (maxVoltage - minVoltage)) * 100.0;
    if (chargeLevel<0){
      chargeLevel=0;
      }
    if (chargeLevel>100){
      chargeLevel=100;
      }
    // Calculate discharge load in Watts
    float dischargeLoadWatts = batteryCapacityWh * dischargeLoadFactor;

    // Estimate remaining discharge time in hours
    // Assuming a linear discharge rate
    float totalHours = (batteryCapacityWh * (chargeLevel / 100.0)) / dischargeLoadWatts;
    int hours = (int)totalHours;
    int minutes = (totalHours - hours) * 60;

    // Output readings
    Serial.print("Battery Voltage: ");
    Serial.print(batteryVoltage, 2);
    Serial.print(" V, Charge Level: ");
    Serial.print(chargeLevel, 2);
    Serial.print(" %, Discharge Load: ");
    Serial.print(dischargeLoadWatts, 2);
    Serial.print(" W, Estimated Remaining Time: ");

    // Print result in hh:mm format
    if (hours < 10) Serial.print("0");
    Serial.print(hours);
    Serial.print(":");
    if (minutes < 10) Serial.print("0");
    Serial.println(minutes);

    delay(1000);  // Delay between readings
}

How It Works