Understanding CCA Testing Standards
SAE J537, EN 50342, and what the numbers actually mean
Published August 14, 2025
Cold Cranking Amps (CCA) is the most quoted specification on automotive batteries — and one of the most misunderstood.
SAE J537 (North American standard). The battery is cooled to -18°C (-0.4°F). It must deliver the rated current for 30 seconds while maintaining at least 7.2V (1.2V per cell for a 6-cell 12V battery).
EN 500 (European standard). Similar temperature (-18°C) but different pass criteria and often yields slightly different numerical ratings for the same physical battery.
Cranking Amps (CA) vs. CCA. CA is measured at 0°C (32°F) and produces higher numbers. Marketing departments sometimes quote CA to appear more competitive — always verify which standard applies.
Reserve Capacity (RC). Measures how many minutes the battery can deliver 25A before reaching 10.5V at 27°C. Useful for estimating runtime with engine off and accessories running.
Practical guidance. For a 2.0L petrol engine in a temperate climate, 400–500 CCA is typical. Diesel engines and large V8s may require 700–900 CCA. Oversizing by 15–20% provides margin for battery aging.
SOLO testing. Every production batch is sampled per SAE J537. Rated CCA values are printed on labels only after passing sample tests at 100% of rated value.
References & Academic Standards
- — SAE J537: Storage Batteries
- — EN 50342-1: Lead-Acid Starter Batteries
- — ISO 8858: Test Methods for Starter Batteries