In this paper, an enhanced-battery-balancing strategy for seven-level inverter is proposed. There are three separate battery strings as the input voltage, the cascaded multilevel inverter and the digital controller. The output seven-level approximate sinusoidal waveform is produced by controlling the conduction period of different levels. The advantages of the proposed multilevel inverter are reducing the switching loss and the harmonic content as well as suitable for high-power applications. By proposed battery-balancing discharging strategy, two higher-capacity batteries are discharged to the load and also charge the lowest-capacity battery to prolong the available time of whole battery strings, efficiently use the battery energy and achieve the battery-balancing discharge. A multilevel inverter is designed for the system with the aged batteries to verify its feasibility and excellence. Finally, simulation and experimental results show that the proposed battery-balancing strategy for multilevel inverters actually and efficiently achieves the battery-balancing discharging function.