BMS 3S 40A Protection Board

The BMS 3S 40A Protection Board is an essential circuit for protecting 3-series lithium-ion or LiPo batteries. It monitors each cell to ensure balanced charging and discharging, extending battery life and preventing damage from electrical faults.

This Battery Management System (BMS) offers up to 40A continuous discharge current, making it perfect for high-power applications such as electric scooters, solar storage systems, and power tools.

Technical Specifications

• Model: BMS 3S 40A

• Battery Type: Li-ion / LiPo (3-cell in series)

• Input Voltage: 12.6V (fully charged)

• Overcharge Voltage: 4.25V ± 0.05V per cell

• Over-discharge Voltage: 2.7V ± 0.1V per cell

• Overcurrent Protection: 40A

• Continuous Discharge Current: 40A

• Charging Current: up to 20A

• Working Temperature: -30°C to +80°C

• Size: Approx. 56mm × 45mm × 4mm

Key Features

✅ Built-in overcharge and over-discharge protection
✅ Prevents short circuits and overcurrent damage
✅ Provides cell balancing for consistent performance
✅ Compact design with nickel strip pads for easy welding
✅ Ideal for 3S Li-ion or LiPo battery packs
✅ Compatible with solar power storage, RC projects, and portable tools

Working Principle

The BMS (Battery Management System) continuously monitors voltage and current for each battery cell in the 3S configuration.

• During charging, it stops charging when any cell exceeds 4.25V.

• During discharging, it cuts off power when any cell drops below 2.7V, protecting the cells from deep discharge damage.

• It balances the charge across all cells to maintain equal voltage levels, ensuring efficient and safe operation.

This intelligent protection makes it ideal for DIY battery packs used in Arduino-based energy projects or solar power modules.

Applications

• 🔋 DIY 3S Li-ion Battery Packs

• 🚴 E-bikes / E-scooters / Electric tools

• ☀️ Solar Energy Storage Systems

• 🏠 Portable Power Banks & Inverters

• ⚙️ Robotics and Embedded Power Systems

• 🔧 Arduino & IoT Energy Projects

Precautions

⚠️ Use only 3S (3-cell) lithium battery configurations.
⚠️ Ensure all cells are balanced before connecting to the board.
⚠️ Avoid reverse polarity connections.
⚠️ Keep away from moisture and conductive surfaces during operation.
⚠️ Use appropriate heat dissipation for high-load applications.

Internal Links

• Arduino Boards

• Power Supply Modules

• Battery Management Systems (BMS)

• DC-DC Converters

YouTube Tutorial

🎥 Watch: How to Connect and Use 3S 40A BMS Protection Board with Li-ion Battery Pack

Summary

The BMS 3S 40A LiPo Battery Protection Board is a must-have for anyone building a reliable lithium battery pack. With 40A discharge capability and multi-level protection, it safeguards your batteries from damage while maximizing performance and life. Whether you’re working on electric vehicles, DIY power systems, or Arduino energy monitoring, this module ensures safe and efficient operation.