4S 18650 Battery Protection Module (BMS)

A 4S 18650 Battery Protection Module (BMS) is an electronic circuit designed to manage and protect a lithium-ion battery pack consisting of four 3.7V cells connected in series (total nominal voltage ~14.8V). This module ensures safe charging and discharging by monitoring voltage, current, and temperature conditions. It prevents damage to the battery pack and extends its lifespan by maintaining balanced operation across all cells.

Technical Specifications:

• Battery Configuration: 4 Series (4S) 18650 Li-ion cells
  
• Nominal Voltage: 14.8V
  
• Charging Voltage: 16.8V – 18V
  
• Continuous Discharge Current: Typically 10A – 40A (model dependent)
  
• Peak Current: Up to ~60A–80A (short duration)
  
• Balance Current: ~50mA – 100mA
  
• Overcharge Protection Voltage: ~4.25V per cell
  
• Over-discharge Protection Voltage: ~2.3V – 3.0V per cell

Features:

• Provides complete protection for lithium battery packs
  
• Prevents overcharging and deep discharge of cells
  
• Built-in balancing function for uniform cell voltage
  
• Short-circuit and overcurrent protection for safety
  
• Compact design suitable for battery pack integration
  
• Low power consumption for efficient operation
  
• Automatic recovery function in many models

Applications:

• DIY battery pack projects
• Electric bicycles and scooters
  
• Power tools and drill machines
  
• Solar energy storage systems
  
• UPS and backup power systems
  
• Portable electronics and robotics
  
• LED lighting and inverter systems