4S 14.8V Li-Ion BMS Protection Board 18650 – 20A
4S 14.8V Li-Ion BMS Protection Board 18650 – 20A
4S 14.8V Lithium Battery Protection Board – Model HX-4S-D20
Keep your 18650 lithium battery packs safe and performing at their best with this compact 4-series (4S) Battery Management System (BMS) protection board. Designed for 14.8V Li-ion packs, it guards against overcharging, over-discharging, and short circuits — all in a slim 35 × 35 × 3.6mm form factor. Made in Mainland China.
Key Features
- Overcharge Protection: Triggers at 4.25–4.35V (±0.05V) per cell to prevent cell damage from excessive charging voltage
- Over-Discharge Protection: Activates at 2.3–3.0V (±0.05V) per cell, safeguarding battery capacity and longevity
- Short Circuit Protection: Automatically cuts power during a short circuit event; recharge to restore normal operation
- 20A Maximum Instantaneous Current: Handles up to 20A peak with a 10A continuous working current limit
- Ultra-Low Static Current: Less than 30µA standby draw, minimizing parasitic drain on your battery pack
- Wide Operating Temperature: Functions reliably from -40°C to +50°C; safe storage up to +80°C
- Long Service Life: Rated for over 50,000 hours of effective operation
- Low Internal Resistance: Less than 100mΩ for minimal energy loss and efficient current delivery
Technical Specifications
| Model | HX-4S-D20 |
| Configuration | 4 Series (4S) |
| Nominal Pack Voltage | 14.8V |
| Charging Voltage | 16.8V – 17V |
| Overcharge Voltage Range | 4.25 – 4.35V ±0.05V |
| Over-Discharge Voltage Range | 2.3 – 3.0V ±0.05V |
| Working Current (Continuous) | 10A |
| Maximum Instantaneous Current | 20A |
| Static Current | <30µA |
| Internal Resistance | <100mΩ |
| Board Dimensions | 35 × 35 × 3.6mm |
| Operating Temperature | -40°C to +50°C |
| Storage Temperature | -40°C to +80°C |
| Protection IC | S-8254AA + D403 ×4 |
| Effective Lifespan | >50,000 hours |
| Package Contents | 1 × Protection Board |
| Country of Origin | Made in Mainland China |
Ideal Applications
This BMS protection board is well suited for DIY battery pack builds, power tool battery assemblies, RC vehicles, solar energy storage systems, e-bikes, and any project requiring a reliable 4S 18650 lithium battery pack management solution.
Related Products You May Like
- 1/2" Drive 8-Piece Hex Short Socket Set – Vanadium Steel
- 10-Piece Gardening Tool Kit – Iron Head & Plastic Handle
- 10-Pc Hex Nut & Bolt Extractor Kit 9–19mm | HIP Tools
Learn more: EPA guidance on lithium-ion battery handling
Frequently Asked Questions
Q: What battery configuration does this BMS protection board support?
A: This is a 4-series (4S) BMS designed for 14.8V nominal lithium-ion (Li-ion) 18650 battery packs. It requires four cells connected in series and is compatible with a charging voltage of 16.8V–17V.
Q: How does the short circuit protection work on the HX-4S-D20?
A: When a short circuit is detected, the board automatically disconnects the load to prevent damage to the cells. To restore normal operation, simply reconnect the charger — the charging current resets the protection circuit.
Q: What are the board dimensions and how compact is it?
A: The board measures just 35 × 35 × 3.6mm, making it easy to integrate into compact battery enclosures, DIY power banks, or custom battery pack housings.
Q: What is the maximum current this board can handle?
A: The board supports a continuous working current of 10A and can withstand a maximum instantaneous current of 20A, making it suitable for moderate-power applications such as power tools and e-bikes.
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.