You can use the MAX471 Voltage & Current Sensor module to test the current and voltage. The principle of voltage test based on principle of resistive voltage divider design, can make the load connected 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.
MAX471 Voltage & Current Sensor Connectivity
GND: All of the grounds are connected to the same electrical point
VOUT: Connects the high side of your load
VIN: Connects to the Positive Pole of your voltage source ( This can be anywhere from 3 to 25 Vdc )
AT: Provides 0 to 5V signal that is scaled to 1 V per amp.
VT: Provides a 0 to 5V signal that is scaled to 1 volt per for every 5 volts input
