Can A Car Battery Be Tested While In The Car. How To Test a Car Battery With a Multimeter. Your cars alternator charges the battery while the vehicle is running.
Place the red lead on the positive battery terminal indicated by a red cover or a symbol. Place the black lead on the negative terminal. Your cars alternator charges the battery while the vehicle is running.
When the engine is running this measurement should be 137 to 147 volts.
That is the battery is not holding the charge it gets from the alternator. Disconnecting car battery cables In this step you should use a wrench to remove positive and negative cables. Because of the way lead-acid batteries discharge its important that you test the battery after its been sitting for a period of time to get whats called the resting voltage. Leave the car overnight preferably longer and test before you start the car in the morning to get an accurate gauge of the batterys health.
