The amp-hour (Ah) rating is similar to the fuel tank capacity of a battery. A higher Ah rating will generally provide longer runtime when comparing compatible batteries under similar conditions. However, actual runtime and performance also depend on the tool, application, workload, battery technology, and operating conditions.
Higher-capacity batteries are often larger and heavier, but newer Milwaukee battery technologies such as REDLITHIUM™ HIGH OUTPUT™ and REDLITHIUM™ FORGE™ can deliver increased performance without relying on capacity alone.