There is probably room for improvement here but this is what I have come up with for a 3.7 Volt LiPo battery meter. In the picture below I am charging my battery from a 5 volt source. All the charge controlling circuitry is built into the battery. I just wanted a way to monitor the charging progress, although, this could certainly be added to any project that uses a 3.7 volt LiPo battery for its power supply.
Hope this helps.

//3.7V LiPo Battery Meter
//3.7V LiPo Battery Meter
//Use two 1.2 K Ohm resisters as a voltage divider from the positive
//and negative terminal of the battery to read reference voltage from.
//we wouldnt want to send to much voltage to our Arduino.
//Make sure to tie the ground back to the Arduino. Otherwise, expect some odd readings.

int sensorPin = 0; //set up the sensor pin for reading the voltage
int sensorValue = 0; //variable to store the value coming from the sensor

void setup()
{
//This is the default value, but we can set it anyways
analogReference(DEFAULT); //5V Reference on UNO
Serial.begin(9600); //initialize serial communication
}

void loop()
{
sensorValue = analogRead(sensorPin); //set sensorValue as an analog read of the A0 pin
//print the value of the sensor multiplied by 0.00326 to get true voltage reading.
//this is a value of 0 – 1023 coming from the sensor pin and has to be converted.
Serial.println(“Battery Voltage Is”);
Serial.println(sensorValue * 0.00951);

delay(1000); //give a delay between readings.
}