2S 7.4V 3A Li-Ion Cell BMS Charging Protection Module

Overview

The 2S 7.4V 3A Li-Ion Cell BMS Charging Protection Module is a compact Battery Management System designed to protect and optimize 2-cell (2S) lithium-ion battery packs. It provides essential safety protections while balancing cells to extend battery life and ensure reliable performance in small electronics, DIY battery packs, robotics, and IoT devices.

Module Overview and Image

Visual reference of the 2S 7.4V BMS module for identification and layout.

Key Features

• Designed specifically for 2S 7.4V lithium-ion battery packs
• Maximum continuous discharge current: 3A
• Overcharge protection to prevent cell voltage exceeding safe limits
• Over-discharge protection to prevent deep discharge and cell damage
• Overcurrent and short-circuit protection for safe operation under fault conditions
• Active cell balancing to improve charge efficiency and battery longevity
• Compact, lightweight PCB for easy integration into custom packs and projects

Protections Included

• Overcharge detection and cutoff
• Over-discharge detection and cutoff
• Overcurrent monitoring and timed cutoff
• Short-circuit detection and immediate protection

Technical Specifications

• Cell configuration: 2S (2 cells in series), nominal 7.4V
• Maximum continuous discharge current: 3A
• Protection functions: overcharge, over-discharge, overcurrent, short-circuit
• Cell balancing: passive balancing to keep cell voltages matched during charge
• PCB: compact, lightweight design for space-constrained applications
• Typical applications: DIY battery packs, robotics, IoT devices, portable electronics

Applications

• Custom Li-ion battery packs for hobby and professional projects
• Robotics and automation projects requiring reliable 7.4V power
• IoT and portable electronics with compact power requirements
• DIY power banks, small gadgets, and rechargeable 7.4V devices

Wiring, Installation and Safety

Follow safe wiring and installation practices when integrating the BMS into your battery pack. Check the silkscreen labels on the PCB before connecting cells or load/charger.

Common terminal designations (verify your board):

• B+ : Battery pack positive terminal
• B- : Battery pack negative terminal
• B1 : Middle tap between cell 1 and cell 2 (cell connection)
• P+ : Pack output/charge positive (sometimes same as B+)
• P- : Pack output/charge negative (sometimes same as B-)

Installation Tips

• Confirm cell voltages and orientation before connecting to the BMS
• Use correct gauge wiring for the expected current (3A continuous rating)
• Secure the board and avoid mechanical stress on solder joints and terminals
• Verify polarity and connections against the PCB silk-screen prior to powering
• Perform initial testing with a current-limited supply or bench test setup

Safety and Best Practices

• Do not exceed the rated continuous discharge current to avoid overheating
• Allow adequate ventilation and avoid enclosing the board in a fully sealed space
• Use matched cells of the same capacity, age, and chemistry for best results
• Observe local regulations for battery handling, charging and disposal
• Images are for illustration purposes only; check the actual product before installation

Why Choose This 2S 7.4V BMS

This module offers reliable multi-level protection and cell balancing in a compact package tailored for low-power 2S Li-ion packs. It is an excellent choice for makers, engineers and hobbyists building custom packs for robotics, IoT and portable devices where safety and longevity matter.