How Do You Test A Car Battery Using A Multimeter?
Using a multimeter, it is both quick and easy to test a car’s battery and charging system. The following steps will show how to identify a failing battery or alternator. Locate the car battery and identify the positive (+, red) and negative (-, black) terminals. The positive terminal may be hidden beneath a protective plastic cover. Set the multimeter to read DC Voltage (DCV) then turn the unit on. Test the surface voltage of the battery. With the car turned off, touch the red lead (positive) of the multimeter to the positive terminal of the battery and the black lead (negative) to the negative terminal. The battery voltage should read between 12.5 and 12.8 volts. If the alternator is providing the proper voltage to the battery (see next step) a reading below 12.5 volts may indicate a failing battery. Test the output voltage from the alternator. Connect the multimeter leads as in the previous step. Start the engine and let the car idle. The multimeter should read between 13.6 and 14.3
