The Crowtail- Voltage Sensor module designed on the basis of the input voltage is not greater than 5 V x 5 = 25 V (if use 3.3 V system, the input voltage is not greater than 3.3 Vx5 = 16.5 V).Because the Aduino using AVR chip for 10 AD, so this module simulation resolution of 0.00489 V (5 V / 1023), so the voltage detecting module minimum input voltage of 0.00489 V * 5 = 0.02445 V.