diff --git a/cores/arduino/Arduino.h b/cores/arduino/Arduino.h
index 91eeb16bc..f4eb2ff2f 100644
--- a/cores/arduino/Arduino.h
+++ b/cores/arduino/Arduino.h
@@ -137,6 +137,8 @@ int digitalRead(uint8_t pin);
 int analogRead(uint8_t pin);
 void analogReference(uint8_t mode);
 void analogWrite(uint8_t pin, int val);
+float batteryVoltageRead(void);
+
 
 unsigned long millis(void);
 unsigned long micros(void);
diff --git a/cores/arduino/wiring_analog.c b/cores/arduino/wiring_analog.c
index 0de64f785..0611d2c8c 100644
--- a/cores/arduino/wiring_analog.c
+++ b/cores/arduino/wiring_analog.c
@@ -27,6 +27,51 @@
 
 uint8_t analog_reference = DEFAULT;
 
+
+float batteryVoltageRead(void)
+{
+#if defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
+#define ADMUX_VCCWRT1V1 (_BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1))
+#elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
+#define ADMUX_VCCWRT1V1 (_BV(MUX5) | _BV(MUX0))
+#elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
+#define ADMUX_VCCWRT1V1 (_BV(MUX3) | _BV(MUX2))
+#else
+#define ADMUX_VCCWRT1V1 (_BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1))
+#endif
+
+// Read 1.1V reference against AVcc
+ // set the reference to Vcc and the measurement to the internal 1.1V reference
+ #if defined(ADMUX)
+ if (ADMUX != ADMUX_VCCWRT1V1)
+ {
+   ADMUX = ADMUX_VCCWRT1V1;
+
+   // Bandgap reference start-up time: max 70us
+   // Wait for Vref to settle.
+   delayMicroseconds(350); 
+ }
+ #endif
+
+ #if defined(ADCSRA) && defined(ADCL)
+ // Start conversion and wait for it to finish.
+ ADCSRA |= _BV(ADSC);
+ while (bit_is_set(ADCSRA,ADSC)) {};
+   
+ // Result is now stored in ADC.
+ 
+ // Calculate Vcc (in V)
+ float vcc = 1.1*1024.0 / ADC;
+ 
+ return vcc;
+
+#else
+ return 0;
+#endif
+}
+
+
+
 void analogReference(uint8_t mode)
 {
 	// can't actually set the register here because the default setting