Final answer:
The major loss in batteries is resistive heating due to internal resistance, described by P = I^2R. Heat generation increases significantly with the charge rate because of the current squared relationship in the formula. Fast charging especially may result in substantial increases in the battery's temperature.
Step-by-step explanation:
The major loss in batteries is typically due to resistive heating caused by the internal resistance of the battery. The resistive heating term that represents heat generation in batteries can be described by the equation P = I2R, where P is the power (heat generated per unit time), I is the current, and R is the internal resistance of the battery. As the charge rate increases, the current (I) also increases. Since the current is squared in the resistive heating equation, even a modest increase in charge rate (current) will result in a significant increase in heat generation. This is why fast charging can lead to substantial heating of the battery, which impacts both performance and longevity.
For example, if a car battery with a 12-V electromotive force (emf) and an internal resistance of 0.050 ohms is being charged with a current of 60 A, the potential difference across its terminals will be modified and the rate of thermal energy (heat) dissipation will be P = I2R = 602 * 0.050 = 180 W. This heating can contribute to a rise in the battery's temperature, potentially reducing its lifespan and efficiency.