Abstract: This paper presents the design and implementation of an intelligent discharge tester for lead-acid battery maintenance in substations. The core of the device adopts a synchronous Buck-Boost topology, with the energy recovery mode as its primary operating mode. In this mode, the circuit operates as a Boost converter, stepping up the battery voltage to a higher level. Subsequently, the electrical energy is efficiently (approximately 95%) fed back into the AC grid via a downstream T-type three-level inverter circuit, achieving a balance between energy conservation and operational safety. Finally, comparative experiments were conducted on battery banks within a 6kV DC system at a substation of Baoti Group. The experimental results demonstrate that, compared to traditional energy-consuming discharge testers, the designed energy-recovery discharge tester not only ensures a higher level of safety but also improves efficiency by approximately 28.67% and reduces energy consumption by 78.31%.