In battery specifications, which unit is standard for rating a battery’s capacity to deliver charge over time (commonly at a specified discharge rate)?

Introduction:
Battery datasheets present several ratings, including capacity, energy, and voltage. Distinguishing between ampere-hours (Ah) and watt-hours (Wh) is critical for selecting and comparing batteries in electronics and power systems.

Given Data / Assumptions:

• Conventional consumer and industrial battery ratings.
• Capacity is defined as total charge deliverable at a specified rate and temperature.
• Energy is a separate quantity derived from voltage and capacity.

Concept / Approach:
Battery capacity measures charge, not energy. The standard unit for capacity is ampere-hour: 1 Ah means the battery can ideally provide 1 A for 1 hour (or 0.5 A for 2 hours, etc.), subject to discharge-rate effects (Peukert's law) and temperature. Energy in watt-hours equals nominal voltage times capacity (Wh = V_nom * Ah).

Step-by-Step Clarification:
1) Identify the sought quantity: capacity (charge over time).2) Match to units: current * time = ampere-hour (Ah).3) Differentiate from energy: energy uses watt-hour (Wh) or kilowatt-hour (kWh).4) Conclude that the correct unit for capacity is Ah.

Verification / Alternative check:
Check common cells: e.g., a 2,500 mAh (2.5 Ah) Li-ion 18650 cell at ~3.6 V has energy ≈ 2.5 Ah * 3.6 V = 9 Wh; this confirms the distinct roles of Ah and Wh.

Why Other Options Are Wrong:
kWh and Wh: units of energy, not charge capacity.
Vh: voltage-time has no standard meaning for capacity.
A/s: ampere per second is a rate-of-change of current, not capacity.

Common Pitfalls:
Confusing capacity (Ah) with energy (Wh). Always consider both capacity and nominal voltage when estimating runtime in watt-hours.

Final Answer:
Ah