Used to read battery charge, then dislpays charge using 3 LED lights on a breadboard connected to an Arduino Uno. 3 Lights On = Above 2/3 charge. 2 Lights = Above 1/3 charge. 1 Light = any charge at all.

Supplies

1* Arduino USB connector

1 * Battery Holder

1* D Cell Battery

2* Aligator Clips with jumper wires

3* 330 OHM Resistor

3* LED

6* Jumper Wires

Step 1: Code

```/*
Reads battery charge, displays charge using 3 LED lights

The circuit:
LED 1 connected to digital pin 13 to ground
LED 2 connected to digital pin 12 to ground
LED 3 connected to digital pin 8 to ground

3 330 OHM resistors connected to the LED lights

Positive charge of battery to analog pin A0
Negative charge of battery to ground on Arduino
*/

int charge; //variable for charge ammount in battery
float PinNumber; //variable for Arduino pin number

void setup() {
pinMode(13, OUTPUT); //Sets Pin 13 to Ouput
pinMode(12, OUTPUT); //Sets Pin 12 to Ouput
pinMode(8, OUTPUT);  //Sets Pin 8 to Ouput
}

void loop()
{
check(); /* reads input from battery on pin A0
and sets as charge value */
delay(1000); //wait 1 second (1000 milliseconds)

if (charge >= 0) {
/* runs statement if the battery has any charge
*/
PinNumber = 13;
on(); //turns on first LED light
}
else { //otherwise turns off
PinNumber = 13;
off(); //turns off first LED light
}

if (charge >= 102.3) {
/*  runs statement if battery charge
is equal or above 1/3  */
PinNumber = 12;
on(); //turns on second LED light
}
else { //otherwise turns off
PinNumber = 12;
off(); //turns off second LED light
}

if (charge >= 204.6) {
/*runs statement if battery charge
is equal or above 2/3*/
PinNumber = 8;
on();  //turns on third LED light
}
else { //otherwise turns off
PinNumber = 8;
off();  //turns off third LED light
}
}

void check() {
}

void on() {
digitalWrite(PinNumber, HIGH);
}

void off() {
digitalWrite(PinNumber, LOW);
}
```

Step 2: Circuit

LED 1 connected to digital pin 13 to ground

LED 2 connected to digital pin 12 to ground

LED 3 connected to digital pin 8 to ground

3 330 OHM resistors connected to the LED lights

Positive charge of battery to analog pin A0

Negative charge of battery to ground on Arduino