Energy performance refers to reducing energy consumption without compromising service quality. While base station (BS) sleeping is a common practice to enhance energy performance, it is rarely implemented in practice due to its negative impact on service quality. This paper addresses this challenge by integrating the local battery of the BS into the BS sleeping design. By synchronizing battery operations with real-time energy prices and network traffic loads, our solution dynamically adjusts BS sleeping parameters to consistently maintain service performance while minimizing operational costs. Our experiments demonstrate significant energy savings with minimal impact on service delays, and the strategic charging policy further reduces energy costs by utilizing low-price electricity periods. This study highlights the considerable potential of battery-powered BSs to improve existing trade-offs in energy performance.