Battery Polarity Detection of New GVDA GD110A New Voltage Tester Pen AC DC 300V LCD Display Mini Voltmeter Break Point Detection Continuity Test Circuit Check
When the tester is on, press and hold the button while touching the test probe to the positive terminal, the other hand press and hold the negative terminal. if the polarity is correct, the screen display "--P" and the buzzer sounds. if it is reversely connected, the test pen doesn't respond.
