Which battery rating is tested at 0°F (-18°C)?

The cold-cranking amperes (CCA) is the battery rating that is specifically tested at 0°F (-18°C). CCA measures the battery's ability to start an engine in cold conditions by indicating how much current the battery can deliver for 30 seconds at that low temperature while maintaining a minimum voltage of 7.2 volts for a 12-volt battery. This measurement is crucial because engines require more power to start in cold temperatures due to increased viscosity of engine oil and other cold-start challenges.

The importance of CCA lies in its ability to help consumers evaluate battery performance under winter conditions. Strong CCA ratings signify that the battery will perform effectively in cold weather, making it a critical factor when selecting a battery for vehicles that are used in regions with harsh winter conditions. While cranking amperes (CA) also measures the battery's ability to start an engine, it is assessed at 32°F (0°C) and thus does not reflect the battery's capability in colder environments as accurately as CCA. Reserve capacity relates to how long a battery can deliver a certain load in the event of failure of the charging system, while a battery voltage test simply measures the voltage present in the battery, not its performance under cold conditions.