Battery_Capacity_Checker

/* 
* Battery Capacity Checker
* 
* Uses 1 Ohm power resister as shunt - Load can be any suitable resister or lamp
* 
* YouTube Video: https://www.youtube.com/embed/qtws6VSIoYk
* 
* Based on adamwelch.co.uk/2016/01/lithium-ion-18650-battery-capacity-checker/ 
* 
* LCD bits removed. Logging to serial only.
* 
* Crudiely modified to deal with 4 batteries
*/
#define highPin1 A0
#define lowPin1  A1
#define gatePin1 11

#define highPin2 A2
#define lowPin2  A3
#define gatePin2 7

#define highPin3 A6
#define lowPin3  A7
#define gatePin3 3

#define highPin4 A8
#define lowPin4  A9
#define gatePin4 2
 
boolean finished1 = false;
boolean finished2 = false;
boolean finished3 = false;
boolean finished4 = false;
 
float mAh1 = 0.0;
float mAh2 = 0.0;
float mAh3 = 0.0;
float mAh4 = 0.0;

float battVolt1 = 0.0;
float battVolt2 = 0.0;
float battVolt3 = 0.0;
float battVolt4 = 0.0;

float shuntVolt1 = 0.0;
float shuntVolt2 = 0.0;
float shuntVolt3 = 0.0;
float shuntVolt4 = 0.0;

float shuntRes = 0.22;  // In Ohms - Shunt resistor resistance
float voltRef = 4.90; // Reference voltage (probe your 5V pin) 
float current = 0.0;
float battLow = 3.0;
 
int printStart = 0;
int interval = 5000;  //Interval (ms) between measurements

unsigned long previousMillis = 0;
unsigned long millisPassed = 0;
 
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);

  Serial1.begin(115200);
  Serial1.println("Battery Capacity Checker v1.1");
  Serial1.println("battVolt   current     mAh");
 
  digitalWrite(gatePin1, LOW);
  digitalWrite(gatePin2, LOW);
  digitalWrite(gatePin3, LOW);
  digitalWrite(gatePin4, LOW);
 }
 
void loop() {
 
  battVolt1 = analogRead(highPin1) * voltRef / 1024.0;
  battVolt2 = analogRead(highPin2) * voltRef / 1024.0;
  battVolt3 = analogRead(highPin3) * voltRef / 1024.0;
  battVolt4 = analogRead(highPin4) * voltRef / 1024.0;

  shuntVolt1 = analogRead(lowPin1) * voltRef / 1024.0;
  shuntVolt2 = analogRead(lowPin2) * voltRef / 1024.0;
  shuntVolt3 = analogRead(lowPin3) * voltRef / 1024.0;
  shuntVolt4 = analogRead(lowPin4) * voltRef / 1024.0;

//BATTERY 1
  if(battVolt1 >= battLow && finished1 == false)
  {
      digitalWrite(gatePin1, HIGH);
      millisPassed = millis() - previousMillis;
      current = (battVolt1 - shuntVolt1) / shuntRes;
      mAh1 = mAh1 + (current * 1000.0) * (millisPassed / 3600000.0);
      previousMillis = millis();
       
      Serial1.print("B1");
      Serial1.print("\t");
      Serial1.print(battVolt1);
      Serial1.print("\t");
      Serial1.print(current);
      Serial1.print("\t");
      Serial1.println(mAh1);
       
      delay(interval);
  }
  if(battVolt1 < battLow)
  {
      digitalWrite(gatePin1, LOW);
      finished1 = true;
       
      delay(interval);
  }

// BATTERY 2
  if(battVolt2 >= battLow && finished2 == false)
  {
      digitalWrite(gatePin2, HIGH);
      millisPassed = millis() - previousMillis;
      current = (battVolt2 - shuntVolt2) / shuntRes;
      mAh2 = mAh2 + (current * 1000.0) * (millisPassed / 3600000.0);
      previousMillis = millis();
        
      Serial1.print("B2");
      Serial1.print("\t");
      Serial1.print(battVolt2);
      Serial1.print("\t");
      Serial1.print(current);
      Serial1.print("\t");
      Serial1.println(mAh2);
       
      delay(interval);
  }
  if(battVolt2 < battLow)
  {
      digitalWrite(gatePin2, LOW);
      finished2 = true;
             
      delay(interval);
  }

// BATTERY 3
  if(battVolt3 >= battLow && finished3 == false)
  {
      digitalWrite(gatePin3, HIGH);
      millisPassed = millis() - previousMillis;
      current = (battVolt3 - shuntVolt3) / shuntRes;
      mAh3 = mAh3 + (current * 1000.0) * (millisPassed / 3600000.0);
      previousMillis = millis();
        
      Serial1.print("B3");
      Serial1.print("\t");
      Serial1.print(battVolt3);
      Serial1.print("\t");
      Serial1.print(current);
      Serial1.print("\t");
      Serial1.println(mAh3);
       
      delay(interval);
  }
  if(battVolt3 < battLow)
  {
      digitalWrite(gatePin3, LOW);
      finished3 = true;

      delay(interval);
  }

// BATTERY 4
  if(battVolt4 >= battLow && finished4 == false)
  {
      digitalWrite(gatePin4, HIGH);
      millisPassed = millis() - previousMillis;
      current = (battVolt4 - shuntVolt4) / shuntRes;
      mAh4 = mAh4 + (current * 1000.0) * (millisPassed / 3600000.0);
      previousMillis = millis();
        
      Serial1.print("B4");
      Serial1.print("\t");
      Serial1.print(battVolt4);
      Serial1.print("\t");
      Serial1.print(current);
      Serial1.print("\t");
      Serial1.println(mAh4);
       
      delay(interval);
  }
  if(battVolt4 < battLow)
  {
      digitalWrite(gatePin4, LOW);
      finished4 = true;
       
      delay(interval);
  }

// All batteries have finished discharging.

  if(finished1 == true && finished2 == true && finished3 == true && finished4 == true)
  {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
  }
}