BMS 4S 40A (Battery Protection and Management Board for Li-ion Batteries)

Key features Type: BMS 4S (for 4 series-connected 3.7V batteries) Nominal voltage: 14.8V Maximum charging voltage: 16.8V Maximum load current: up to 40A Balancing: yes (cell voltage equalization) ⚙️ Protection functions The board ensures safe operation of the battery pack: overcharge protection over-discharge protection short-circuit protection overcurrent protection cell balancing 🔌 Connection B- — negative terminal of the entire battery (0V) B1 / B2 / B3 — intermediate points between the batteries B+ — positive terminal of the last battery (16.8V) P+ / P- — output to the load and charger 🔧 Applications cordless screwdrivers and drills pack assemblies made from 18650 cells high-power power banks power tools and DIY projects portable power systems ⚠️ Important For correct operation, be sure to use: batteries of the same type and capacity equally charged cells correct wiring scheme Incorrect connection may cause the board to fail.