How Many Volts Should Your Car Battery Have. How to tell if a car battery is bad or dying. At 120 volts theres much less than a 50 chance that a known good battery will crank the engine over.
When the Car Is Running. Each battery has six cells each with 21 volts at full charge. When your car is running your battery should register between 137 and 147 volts.
These measurements indicate your alternator and your battery are fine.
How to tell if a car battery is bad or dying. Recharge the battery and test it again later to see if its holding a charge. 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. When the engine is in functioning mode this capacity should be increase to 137 to 147 volts.
