BMS 3S 12V 40A Lithium Battery Protection Board – 18650
BMS 3S 12V 40A Lithium Battery Protection Board – 18650
diymore 3S 12V 40A BMS Lithium Battery Protection Board for 18650 Cells
Keep your 3-cell lithium battery pack running safely and efficiently with the diymore BMS 3S 12V 40A Battery Management System Protection Board. Designed for nominal 3.6V/3.7V 18650 lithium cells wired in a 3S (series) configuration, this compact module safeguards your pack from overcharge, over-discharge, overcurrent, and short-circuit events — all through a single shared port for charging and discharging. Made in Mainland China.
Key Features
- Same-Port Design: Charging and discharging share a single port, simplifying wiring and reducing connector count.
- High Continuous Discharge: Supports up to 40A continuous discharge current (maximum), suitable for demanding applications.
- Controlled Charge Current: Handles up to 20A continuous charge current (maximum) for fast, controlled top-ups.
- Wide Charging Voltage Range: Compatible with chargers outputting 12.6V – 13.6V, covering standard 3S lithium charger profiles.
- Compact & Easy to Install: Measures just 42 × 55 × 3.4 mm — fits neatly into battery enclosures, DIY power tools, e-bikes, and more.
- Low Power Dissipation: Energy-efficient design minimises standby drain and heat generation.
- Durable Build: Premium-grade components ensure a long operational lifespan and stable performance cycle after cycle.
Technical Specifications
| Configuration | 3S (3 cells in series) |
| Nominal Cell Voltage | 3.6V / 3.7V |
| Pack Voltage | 12V (nominal) |
| Charging Voltage | 12.6V – 13.6V |
| Max Continuous Discharge Current | 40A |
| Max Continuous Charge Current | 20A |
| Dimensions | 42 × 55 × 3.4 mm |
| Port Type | Same Port (charge & discharge) |
| Package Type | TQFP module |
| Condition | Brand New |
| Country of Origin | Made in Mainland China |
What's in the Box
- 1 × BMS 3S 12V 40A Lithium Battery Protection Board
Great Pairings for Your DIY Electronics Projects
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Looking for more DIY project components? Browse our store for related modules and components that complement your battery build.
Learn more: ENERGY STAR product efficiency guidance
Frequently Asked Questions
Q: What battery type is this BMS 3S 40A protection board compatible with?
A: This BMS protection board is designed for 3-cell series (3S) lithium-ion or lithium polymer batteries with a nominal cell voltage of 3.6V or 3.7V — such as the popular 18650 format. The pack operates at 12V nominal with a charging voltage range of 12.6V to 13.6V.
Q: What does "same port" mean on this lithium battery protection board?
A: "Same port" means the board uses a single connector for both charging and discharging operations. This simplifies your wiring, reduces the number of connectors needed, and makes the design more compact — ideal for tight battery enclosures and DIY builds.
Q: Can this BMS handle high-draw applications like power tools or e-bikes?
A: Yes. With a maximum continuous discharge current of 40A, this 3S BMS board is well-suited for moderate-to-high current applications. However, if your thermal environment is limited, it is advisable to reduce the load current to prevent excess heat build-up and maintain long-term board reliability.
Q: What are the physical dimensions of this protection board?
A: The board measures 42 mm × 55 mm × 3.4 mm, making it very compact and easy to integrate into custom battery packs, enclosures, and electronic projects.
Production & Packaging Notice
To maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.