The 4S 8A 16.8V Li-Ion Battery Protection Board (BMS) is a compact battery management solution designed for 4-cell lithium-ion battery packs built with 18650 cells. It provides essential protection during charging and discharging by monitoring battery voltage and current conditions. The board helps prevent overcharging, over-discharging, overcurrent, and short-circuit damage, improving battery safety and extending battery life. With low quiescent current and compact dimensions, it is suitable for portable electronics, LED lighting systems, DIY battery packs, robotics projects, and energy storage applications.