Ampere hour efficiency of a storage cell is 0.85. Average terminal voltage during discharging is 2.1 V and average terminal voltage during charging is 2.55 V. What is the Watt Hour efficiency ?
Ampere hour efficiency of a storage cell is 0.85. Average terminal voltage during discharging is 2.1 V and average terminal voltage during charging is 2.55 V. What is the Watt Hour efficiency ?
Right Answer is:
0.7
SOLUTION
- Ampere-hour efficiency = 0.85
- Average terminal voltage during discharging (V_discharge) = 2.1 V
- Average terminal voltage during charging (V_charge) = 2.55 V
Understanding Ampere-Hour Efficiency:
- Ampere-hour efficiency is the ratio of the ampere-hour capacity of a battery on discharge to its ampere-hour capacity on charge. It represents the efficiency of the battery in storing and delivering electrical energy.
Calculating Watt-Hour Efficiency:
- Watt-hour efficiency takes into account both the ampere-hour efficiency and the voltage changes during charging and discharging. It’s calculated as follows:
Watt-hour efficiency = Ampere-hour efficiency × (Vdischarge / Vcharge)
Substituting the given values:
- Watt-hour efficiency = 0.85 × (2.1 V / 2.55 V)
Calculating the result:
Watt-hour efficiency = 0.85 × 0.8235 ≈ 0.7