How is the ampere hour capacity for a lead acid battery determined?

The ampere-hour (Ah) capacity of a lead-acid battery is determined through a controlled discharge test, where the battery is discharged at a consistent current until it reaches its cutoff voltage. This test measures the total amount of current (in amperes) that the battery can deliver over a specific time period (in hours) before the voltage drops below a defined threshold. Typically, the capacity is expressed as the product of the discharge current and the time taken to reach that voltage level, providing a clear indication of the battery's energy storage capability. Factors such as temperature, discharge rate, and battery age can influence the measured capacity.