CCA (Cold Cranking Amps)
Current the battery can deliver at -18°C for 30 seconds while keeping above a minimum voltage. Determines cold-start capability.
CCA (Cold Cranking Amps) measures how many amperes the battery can deliver at -18°C for 30 seconds without the voltage falling below a minimum threshold (with the battery at 100%). It is the critical specification for cold climates: the higher the CCA, the better the winter starting. A typical petrol passenger car needs 300-500 CCA; a large diesel engine requires 600-900 CCA. Several standards apply slightly different criteria: EN (European, the most common in Europe), SAE (American), IEC and JIS. CCA values published under different standards are not 100% interchangeable; manufacturers usually quote CCA EN on their datasheets and, where relevant, also publish CCA SAE separately.
When replacing a battery, always fit one with CCA equal to or higher than the original — lowering the CCA can leave you unable to start the car at -10°C. Example: a Varta E11 has 800 CCA (EN) and starts any European diesel comfortably. In warm climates (above 0°C habitually) CCA is less critical than Ah.