A battery is charged at a potential of 15 V in 8 h when the current flowing is 10A. The battery on discharge supplies a current of 5A for 15 h. The mean terminal voltage during discharge is 14V. What is the watt-hour efficiency of the battery?

Step-by-step solution

The power of the battery, when charged is given by P 1 = V 1 I 1 The electrical energy dissipated is given by E t = P 1 t 1 E 1 = V 1 I 1 T 1 = 15 × 10 × 8 = 1200 W h Similarly, the electrical energy dissipated during the discharge of battery is given by E 2 = V 2 I 2 t 2 = 14 × 5 × 15 = 1050 W h Hence, watt-hour efficiency of the battery is given by η = E 2 E 1 × 100 = 0.875 × 100 = 87.5 %