They know the Watt-hour capacity of the battery (~70 Wh) and they now know how many watts each activity takes in steady state (W). What's the non-linearity? Doe

They know the Watt-hour capacity of the battery (~70 Wh) and they now know how many watts each activity takes in steady state (W). What's the non-linearity? Does the power usage of those activities change with time, or does the integral capacity of the battery change?