Battery Capacity: What Unit Is Correct? Evaluate the statement: “The capacity of a battery is measured in milliamperes.”

Introduction / Context:
Battery datasheets specify capacity so designers can estimate runtime and energy availability. The correct unit distinguishes instantaneous current from accumulated charge over time, which is crucial when comparing chemistries or discharge profiles.

Given Data / Assumptions:

• Battery capacity expresses total charge delivered under defined conditions.
• Common units: ampere-hour (Ah) or milliampere-hour (mAh).
• Instantaneous current is in amperes (A), not ampere-hours.

Concept / Approach:

Capacity measures charge, not instantaneous current. 1 Ah equals 3600 coulombs. Current (A) indicates rate of charge flow, whereas capacity (Ah or mAh) indicates how much charge the battery can deliver before reaching its cutoff voltage under a specified discharge rate and temperature.

Step-by-Step Solution:

Verification / Alternative check:

Check any commercial cell (e.g., 18650 Li-ion): capacity is specified as 2500 mAh, not 2500 mA. Discharge graphs show current on the vertical axis (A) and capacity as Ah or mAh achieved until cutoff.

Why Other Options Are Wrong:

“True,” “True only for small cells,” and rate-related claims confuse current with capacity. Whether primary or secondary, capacity is charge-based, not current-based.

Common Pitfalls:

Mixing up energy (Wh) and capacity (Ah): energy also depends on voltage; two batteries with the same Ah but different voltages store different Wh.

Final Answer:

False