This module is based on the design principles of the resistor divider, to make the terminal interface input voltage narrow five times, Arduino analog input voltage up to 5V, then the input voltage of the voltage detection module can not be greater than 5V × 5 = 25V (3.3V if used system, the input voltage can not exceed 3.3Vx5 = 16.5V). Because Arduino AVR chips used in 10 A/D, so the resolution of this module is the analog 0.00489V (5V / 1023), so the voltage detection module detects a minimum input voltage of 0.00489V × 5 = 0.02445V.
