What does the capacity of a battery refer to?

The capacity of a battery refers to the amount of electric charge it can deliver, which is typically measured in amp-hours (Ah). This metric indicates the total quantity of electricity the battery can provide over a specified period, often expressed as a rate of current over time. For example, a battery with a capacity of 10 amp-hours can theoretically deliver 10 amps for one hour or 5 amps for two hours before it is exhausted. This measurement is crucial for understanding how long a device can run before needing a recharge, making it a vital consideration in applications ranging from small electronic devices to larger renewable energy systems.

In contrast, the physical size of a battery does not directly correlate with its capacity. Voltage indicates the potential difference provided by the battery but does not measure how much charge it can deliver. Finally, lifespan in years pertains to how long a battery can last before its performance deteriorates, rather than the amount of charge it can provide. Thus, the definition of battery capacity is strongly tied to its performance in delivering electric charge over time.