What Voltage Should A Car Battery Be. When the engine is running this measurement should be 137 to 147 volts. When in the run 137 volts up to 14.
The resting voltage should ideally be no lower than 126V. Bear in mind that when a battery goes down to 122V its actually only 50 charged and below 12V its classed as discharged. When the probes touch the terminals while the car is off and the battery is resting the multimeter display should show a reading of 122 to 126 volts full charge.
There is a very big difference when a car battery drops even a small amount of voltage.
Fully charged voltage. For example 122 volts indicates that the battery is 50 percent discharged. An AGM type cell will be lower about 128 Vdc. The same is true when measuring battery voltage to determine if a battery has gone bad.
