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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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The capacity of a battery is expressed in terms of
current rating
voltage rating
ampere-hour rating
none of the above
ampere-hour rating
Quick Summary: The capacity of a battery is defined as the total amount of electric charge it can deliver under specified conditions, typically measured in Ampere-hours (Ah). This rating represents the product of current in Amperes and time in hours for which the battery can supply that current until its voltage drops to a predefined cutoff limit.
The capacity of a battery is defined as the total amount of electric charge it can deliver under specified conditions, typically measured in Ampere-hours (Ah). This rating represents the product of current in Amperes and time in hours for which the battery can supply that current until its voltage drops to a predefined cutoff limit.
C=I×t — where C is capacity in Ah, I is discharge current in Amperes, and t is time in hours.
E=V×I×t — where E is the total energy in Watt-hours (Wh).
The capacity is derived from the chemical energy stored within the battery cells. The discharge process involves a chemical reaction that releases electrons at a rate proportional to the load current. As the active materials in the electrodes are consumed or the electrolyte concentration changes, the terminal voltage gradually declines; once it hits the 'end-of-discharge' voltage, the battery is considered exhausted.
Ampere-hour (Ah) rating is independent of voltage rating for capacity classification.
Actual capacity depends on the discharge rate (Peukert's Law) and temperature.
Higher discharge currents typically lead to lower effective Ah capacity due to internal resistance losses.
Battery capacity indicates how long a load can be powered before recharging is necessary.
Provides a standardized metric for comparing battery life.
Allows for easy calculation of required battery size for specific load durations.
Does not account for depth of discharge (DoD) limitations.
Capacity rating can be misleading if the specific discharge rate is not specified.
Sizing Uninterruptible Power Supplies (UPS).
Designing solar photovoltaic storage systems.
Automotive battery specifications.
The C-rating is often used alongside Ah to define the discharge rate (e.g., a 100Ah battery discharged at 0.1C means drawing 10A).
Option A is incorrect because current rating is an instantaneous parameter, not a total capacity measure.
Option B is incorrect because voltage rating signifies the potential difference and chemical composition, not the total energy storage capability.
C is correct — Battery capacity is defined by the product of discharge current and time, expressed as Ampere-hours (Ah).
In competitive exams, remember that Capacity (Ah) × Voltage (V) gives Energy (Wh); don't confuse charge capacity with energy storage capacity.