This industry rating measures the power a battery has available to start a vehicle’s engine at -17.8 degrees celcius or zero degrees Fahrenheit.For a 12V SLI (Starting, lighting, ignition) battery, BCI defines CCA as the amount of current (number of amperes) a lead-acid battery at -17.8 degrees celcius or 0 degrees Fahrenheit can deliver for 30 seconds while maintaining at least 7.2 volts.