3S 40A 12.6V Lithium Battery Protection Board with Balance Function – BMS Module

The 3S 40A Balanced Version BMS (Battery Management System) is designed to protect and manage 3-cell lithium battery packs with nominal voltages of 3.7V per cell (including 18650, 26650, and Li-Po types). This version supports balanced charging, helping maintain equal voltage levels across all cells, thus prolonging battery life and ensuring safer operation.

With a continuous discharge current of up to 40A, it is ideal for high-drain applications such as electric drills and power tools that require a starting current below 80A and power under 170W. The built-in auto-recovery function ensures the module resets automatically after overcharge, over-discharge, or overcurrent events.

⚠️ Important: Only use with matched cells of similar capacity and internal resistance to ensure optimal performance and safe operation. Do not use with standard low-drain 18650 cells for power tools.

✅ Key Features:

• Model: 3S 40A Lithium Battery BMS (Balanced Version)
• Balanced Charging: Ensures even voltage across all cells during charge
• Auto-Recovery: Recovers automatically from overcharge/over-discharge
• High Load Capability: Supports 40A continuous discharge, suitable for electric drills
• Built-in Protection: Overcharge, over-discharge, overcurrent, and short circuit protection

? Specifications:

• Battery Type: 3-cell lithium battery packs (18650 / 26650 / Li-Po)
• Charging Voltage Range: 12.6V – 13.6V
• Continuous Discharge Current: Max 40A
• Continuous Charging Current: Max 20A
• Recommended Load: ≤170W (starting current <80A)
• Dimensions: 41 × 60 × 3.4 mm (Balanced Version)
• Weight: 9.8g

⚙️ Precautions:

• Use only high-rate discharge batteries (15C-20C or higher).
• Avoid mixing old and new or low-quality batteries.
• Ensure proper connection of 0V, 4.2V, 8.4V, 12.6V terminals.
• Mild heating of the “430” resistor during charging is normal and indicates balancing.