LED
LCD
Product Description
This 3S 20A Lithium Battery Protection Module (BMS) is a high-performance electronic management circuit engineered to monitor, balance, and safeguard a 3-cell series ($11.1\text{V}$–$12.6\text{V}$) Lithium-Ion or Lithium-Polymer battery pack. Designed to manage a continuous discharge current of up to 20A, this module provides comprehensive protection against overcharging, over-discharging, overcurrent, and short-circuits. It acts as an indispensable supervisor, preventing cell degradation and dangerous thermal events during high-drain operations. For electronics developers, hardware technicians, and robotics engineers, this compact BMS provides a highly reliable and essential safety foundation for upgrading cordless power tools, building portable field instruments, and engineering custom battery packs.
Pinout / Layout Connections
The module features clearly labeled, heavy-duty solder pads on its printed circuit board:
Battery Connection Pads:
0V / B- Pad: Connects directly to the main negative terminal of the first battery cell.
3.7V / B1 Pad: Connects to the junction between the first and second cell.
7.4V / B2 Pad: Connects to the junction between the second and third cell.
11.1V / B+ Pad: Connects directly to the main positive terminal of the third battery cell.
Charge / Discharge Interfaces:
P+ Pad: The positive terminal for both charging input voltage and discharging load output.
P- Pad: The negative terminal for both charging input voltage and discharging load output.
Applications
Cordless Power Tools: Repairing and upgrading standard 12V drill battery packs to high-capacity Li-ion setups.
Robotics & Automation: Providing safe, regulated onboard power distribution arrays for mobile robotic chassis and quadcopters.
Portable Electronics: Building long-lasting power supplies for field-testing gear, custom audio amplifiers, and remote sensor nodes.
Backup Power Infrastructure: Assembling compact 12V uninterruptible power supplies (UPS) and small solar energy storage banks.
Technical Specifications
| Parameter | Value / Specification |
| Module Type | 3S Lithium Battery Protection Board (BMS) |
| Supported Chemistries | 3.7V Lithium-Ion (18650) / 3.7V Lithium-Polymer |
| Series Cell Configuration | 3S (3 Cells in Series) |
| Charging Voltage Range | DC 12.6 V to 13.0 V |
| Max Continuous Discharge Current | 20 A |
| Overcharge Voltage Detection Range | $4.25\text{ V} \pm 0.05\text{ V}$ (Per Cell) |
| Over-discharge Voltage Detection Range | $2.50\text{ V} \pm 0.05\text{ V}$ (Per Cell) |
| Short-Circuit Protection | Integrated with automatic recovery capability |
| Dimensions | ~59 mm x 20 mm x 3.4 mm |
