Lead-acid cell has a life of nearly charges and discharges

Question

Examoogle · Accepted Answer

1250

Explanation: A standard Lead-Acid cell typically provides a cycle life of approximately 1000 to 1250 charge-discharge cycles under optimal operating conditions. This life expectancy is largely dependent on the Depth of Discharge (DoD), temperature, and maintenance practices.

Working Principle: The Lead-Acid battery functions through a reversible electrochemical reaction involving Lead (Pb) and Lead Dioxide (PbO2) plates submerged in a Sulfuric Acid (H2SO4) electrolyte. Repeated cycling causes gradual physical degradation, such as the shedding of active materials from the plates (sulfation) and the eventual loss of porosity, which limits the battery's capacity and overall cycle life.

Key Formulas: $Pb + PbO_2 + 2H_2SO_4 \leftrightarrow 2PbSO_4 + 2H_2O$ — The chemical reaction occurring during discharge (left to right) and charge (right to left).; $Q = \int I dt$ — The total charge capacity which degrades over the cycles.

Key Points: Cycle life is defined as the number of cycles a battery can complete before its capacity drops to a threshold percentage (usually 80% of rated capacity).; High Depth of Discharge (DoD) significantly reduces the total number of cycles a battery can withstand.; Improper maintenance like overcharging or leaving the battery in a discharged state for long periods promotes sulfation, shortening the lifespan.; Optimal temperature for Lead-Acid cells is typically 25°C; higher temperatures accelerate electrolyte evaporation and grid corrosion.

Advantages: Low cost per watt-hour; High surge current capability

Disadvantages: Low energy density compared to Li-ion; Sensitive to deep discharge and long-term sulfation

Applications: Automotive starter batteries; Uninterruptible Power Supply (UPS) systems

Additional Info: The rated life varies based on the manufacturer's design, such as tubular plate or flat plate construction.. Options A, B, and C are considered lower bounds for high-quality industrial Lead-Acid cells, whereas 1250 represents a realistic upper-tier standard for well-maintained deep-cycle units.

Answer: D is correct — The standard operational life for a typical Lead-Acid cell is approximately 1250 charge-discharge cycles under controlled conditions.

Exam Tip: In competitive exams, always check if the question implies 'Deep Cycle' batteries, which may have longer lives, or 'SLI' (Starting, Lighting, and Ignition) batteries, which usually have lower cycle lives.

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