Versatile compatibility: This 2S/3S/4S BMS Liion Battery Lithium Capacity Indicator Display is designed for 8.4V, 12.6V, and 16.8V systems, enabling use across a range of lithium battery applications. Userfriendly operation: To use the LCD Charge Power Level Tester, press the red button gently during charging or discharging. The LED indicators show current flow, with a line current draw of approximately 30 mA. Reverse connection protection: The PCB module includes a builtin reverse protection function, ensuring safe operation even if the line is connected incorrectly. Suitable for both beginners and experienced users. Clear power level indicators: Five small lights visually display power levels across L1 to L5, allowing you to monitor battery status at a glance. Practical use scenarios: Build and monitor 2S/3S/4S Liion packs for RC cars, drones, or portable tools. Perform onthego checks during charging or discharging to quickly assess remaining capacity. Prototype or troubleshoot BMS connections with confidence thanks to reverse protection and clear level indicators.