This module is based on principle of resistive voltage divider design, can make the red terminal connector input voltage to 5 times smaller.
Arduino analog input voltages up to 5 v, the voltage detection module input voltage not greater than 5Vx5=25V (if using 3.3V systems, input voltage not greater than 3.3Vx5=16.5V).
Arduino AVR chips have 10-bit AD, so this module simulates a resolution of 0.00489V (5V/1023), so the minimum voltage of input voltage detection module is 0.00489Vx5=0.02445V.
Output interface: "+ "connected 5/3.3V, "-" connected GND, "s" connected Arduino AD pins.
Specification：
DC 0~25V Voltage Detection Module Sensor
Voltage input range: DC0-25 V
Voltage detection range: DC0.02445 V-25 V
Voltage analog resolution: 0.00489 V
DC input interface: red terminal positive with VCC, negative with GND