At what voltage should I replace my car battery?
At what voltage should I replace my car battery? The battery must maintain a minimum post voltage of 9.6 Volts at 70 degrees F during the test to pass. If the voltage drops below 9.6 volts, the battery is “bad” and needs to be replaced. What should the voltage be on a bat alternator? Measure the voltage across the battery and the big bat alternator terminal to alternator case. There are two things that you are looking for. The charging voltage should be between 13.9v to 14.4v. Also the voltage at the battery and the voltage at the alternator should...