Extending the lifetime of lithium-ion batteries beyond their end-of-life in electric mobility applications is a sustainable pathway to reduce environmental impact and improve resource utilization. Batteries retired from electric ferry operations typically retain substantial residual capacity compared with those from ground electric vehicles, mainly due to their comparatively lower dynamic loading profiles. This makes them promising candidates for second-life battery energy storage system (BESS) applications. However, aging-induced degradation and uncertainties in operational behaviour resulting from their first life require carefully designed charging strategies to ensure safe, efficient, and long-term operation. This paper presents a preliminary investigation towards identifying suitable charging strategies for second-life batteries. Different charging strategies are evaluated for second-life BESSs utilizing retired electric ferry cells, with particular emphasis on extending battery lifetime and supporting sustainable operation. These include constant current–constant voltage (CC–CV), multistage constant current (MCC), constant power (CP), and boost charging (BC). Their impacts on battery lifetime are assessed in terms of capacity degradation, charging duration, impedance evolution, and cell surface temperature trends. The results demonstrate that cells cycled using the BC protocol exhibit the highest degradation, whereas the MCC protocol results in the lowest degradation, but at the expense of increased charging time. In comparison, the CC–CV and CP strategies provide a favourable compromise between charging duration and degradation. These findings highlight charging strategy selection as a critical factor for extending the service life and supporting the sustainable deployment of second-life batteries in stationary energy storage applications.