   } else {
     messageString = messageString + String(tempC, 2);
   }
+  messageString = messageString + " V:";
+  messageString = messageString + String(Vin, 2);
   messageString = messageString + "\n";
 
   // Prepare and send message


#define LED_PIN_TX 13   // the number of the LED pin on the transmitter board
#define ONE_WIRE_BUS 3 // Data wire is plugged into pin 3 on the Arduino

RH_ASK driver;
OneWire oneWire(ONE_WIRE_BUS); // Setup a oneWire instance to communicate with any OneWire devices

  Serial.println("Getting temperatures...");
  sensors.requestTemperatures();
  tempC = sensors.getTempC(firstThermometer);

  // Get and print battery voltage
  Serial.println("Getting voltage...");
  // 9v = 3.85, 6v = 2.55, 11.9v = 5.00 => k = 2.35, 
  float Vin = 2.35 * (analogRead(1) * (5.0/1023.0));
  
  // Make message, e.g. "I:1 T:22.50 \n"
  messageString = "I:";
  messageString = messageString + String(messageId, DEC);
  messageString = messageString + " T:";
