How much electricity does a car battery hold?

There is no standard capacity for automotive batteries. Automobile manufacturers provide batteries that match the specific requirements of different makes and models of cars. Automotive batteries are generally rated for CCA or cold cranking amps. The CCA is the number of amps that a 12.6 volt car battery should be able to deliver at 0°F (−18°C) for thirty seconds without dropping lower than 7.2 volts. A battery with a high CCA rating will be more reliable for starting a car in very cold weather.