General description The 5Pcs 5S 18V 21V 20A Lithium Battery Charging Protection Board Circuit BMS Module is designed for 5 series Li-ion batteries, primarily used in electric power tools. It features a specialized IC that monitors the real-time voltage, charge and discharge current, and temperature of each battery, ensuring optimal performance and safety. Technical specifications Charging voltage: 19/21V Single cell charging voltage: 3.8/4.25V Continuous discharge current: 8-20A Overcharge single cell detection voltage: 3.85-4.25V Overcharge protection time: 1s Overcharge single cell recovery voltage: 3.75-4.13V Overcharge protection release time: 1ms Over-discharge single cell detection voltage: 2-2.8V Over-discharge protection time: 1s Over-discharge single cell recovery voltage: 2.5-3.0V Over-discharge protection release time: 100 +/- 20ms Over-current detection voltage: 0.1-0.4V Over-current detection current: 30 +/- 5A Over-current detection time: 1s Short circuit protection: Yes