4S 40A 18650 Li-Ion Battery Protection Board with Balance (14.8V)

This 4S 40A Battery Management System (BMS) board is designed for assembling custom 14.8V lithium-ion battery packs. Featuring an integrated cell balancing circuit, it is an essential component for builders creating DIY 18650 or 21700 power arrays for field charging stations, ground station monitors, or high-capacity endurance fixed-wings.

Key features

• Integrated cell balancing ensures even charge distribution and prolongs pack lifespan.
• Supports up to 40A continuous discharge current for high-demand applications.
• Hardware-level protection against overcharge, over-discharge, overcurrent, and short circuits.
• Compatible with standard 3.7V nominal lithium-ion or LiPo cells (including 18650, 26650, and 21700 sizes).

Specifications

• Configuration: 4S (4 cells in series)
• Nominal Voltage: 14.8V
• Full Charge Voltage: 16.8V
• Continuous Discharge Current: 40A (max)
• Supported Chemistry: Lithium-Ion / LiPo (Not compatible with LiFePO4)

When assembling your pack, ensure all cells are voltage-matched before connecting them to the BMS. Standard lithium-ion cells require proper spot welding to avoid heat damage to the internal chemistry. A regulated 16.8V DC power source is required for safe charging.