Intelligent Management for Second-Life Lithium-Ion Batteries with Backup Cells

Governments and the market have stimulated replacing fossil fuel vehicles with electric mobility. As a direct effect, the demand for Lithium-ion batteries (LIB) has risen significantly. This technology has several advantages compared with other storage systems, especially the high energy density, capacity, long lifetime, and cycles. On the other hand, LIB is still expensive and is suitable for vehicles when its remaining LIB lifetime is above 80%. After that, the batteries do not satisfy the demands. Since recycling is complex and takes a long time, LIB is used as second-life batteries (SLB) for stationary systems and low-speed vehicles. Although the SLB has low performance, they need smart mechanisms to fit the application, operate under safe conditions, and perform the maximum possible cycle time. Therefore, this work presents an intelligent Battery Management System (BMS) to prolong the discharge time (DT) of a mini-packing of four cells, one of which is used as a reserve. Two configurations were present to guarantee the longest discharge cycle time and avoid cell failures. The first version could improve the DT by 22%, while the second increased to 72%. Therefore, the proposed mechanism is suitable for prolonging the DT of LIB for SLB applications such as stationary solutions or low-speed vehicles.