What is meant by the capacity rating of a lead-acid battery?

• A. Number of hours a battery can supply a given current flow
• B. Maximum voltage of the battery
• C. Total energy stored in watt-hours
• D. The amount of charge in coulombs

Answer: (A)

Capacity rating tells you how long a lead-acid battery can supply a specified current, usually expressed in ampere-hours. In practical terms, it answers how many hours the battery can deliver a given current before it reaches its end-of-discharge voltage. This is the time-based measure of how much current the battery can sustain, governed by the relation Ah = current (A) × time (h). So a battery rated at 50 Ah can, in simple terms, supply 5 A for about 10 hours, assuming standard conditions and discharge criteria.

This differs from maximum voltage, which is simply the electrical potential, and from total energy stored, which is measured in watt-hours (Ah times the nominal voltage) and represents energy rather than the time the battery can sustain a load. It also differs from coulombs, which is a unit of charge. The capacity rating focuses on how long the battery can deliver a given current, not the instantaneous voltage, total energy, or total charge.