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

The 3S 40A Balanced Version BMS (Battery Management System) is a specialized module designed to safeguard and manage 3-cell lithium battery packs, including 18650, 26650, and Li-Po types. Each cell carries a nominal voltage of 3.7V. This BMS module features a balance function that ensures equal voltage levels across all cells, thereby extending battery lifespan and promoting safer operation.With a capacity for a continuous discharge current of up to 40A, this BMS module is perfect for high-drain applications such as electric drills and power tools that require a starting current below 80A and power under 170W. The module's built-in auto-recovery function guarantees that the system resets automatically after overcharge, over-discharge, or overcurrent events.

⚠️ Important: For optimal performance and safe operation, only use this BMS module with matched cells of similar capacity and internal resistance. Standard low-drain 18650 cells for power tools are not suitable.

✅ Key Features:

• Model: 3S 40A Lithium Battery BMS (Balanced Version)
• Balanced Charging: Maintains even voltage across all cells during charging
• Auto-Recovery: Automatically recovers from overcharge/over-discharge
• High Load Capability: Supports 40A continuous discharge, ideal for electric drills
• Built-in Protection: Provides 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.