Its primary functions include real-time monitoring of battery physical parameters, state estimation, online diagnostics and alerts, charge/discharge and precharge control, cell balancing, and thermal management. Failure in any of these functions can cause severe battery damage. BMS (battery management system) is a critical component that connects the traction battery to the vehicle. This is especially important for lithium-ion technology, where the batteries must be protected against. In this article, we will discuss battery management systems, their purpose, architecture, design considerations for BMS, and future trends.