18650 BMS Protection Board 4S-7S 16.8V-29.4V 18A Li-ion Balance

18650 Li-ion BMS Protection Board – 4S/5S/6S/7S | 16.8V–29.4V | 18A Balanced Charging

Keep your lithium battery packs running safely and efficiently with this versatile Battery Management System (BMS) Protection Board. Designed for 4S, 5S, 6S, and 7S configurations, this board is compatible with LMO and ternary lithium (NMC) 18650 cell packs. It delivers reliable overcharge, over-discharge, and short-circuit protection — all in a compact, durable form factor perfect for DIY power tools, e-bikes, RC vehicles, and custom battery builds.

Made in Mainland China.

Key Features

• Wide Voltage Compatibility: Supports 4S (16.8V), 5S (21V), 6S (25.2V), and 7S (29.4V) lithium battery configurations in one board
• 18A Continuous Working Current with 26A instantaneous surge protection
• Active Cell Balancing: 56mA balancing current ensures each cell charges evenly for longer pack lifespan
• Overcharge Protection: Triggers at 4.25V ± 0.025V per cell to prevent over-voltage damage
• Over-Discharge Protection: Cuts off at 2.7V ± 0.5V per cell to protect cells from deep discharge
• Short-Circuit Protection: Automatically detects and cuts short circuits, then recovers after a safe delay
• Compact & Durable: Measures just 60 × 40 × 6mm — easy to integrate into tight battery enclosures
• Plastic + Metal Construction for structural rigidity and thermal stability

Technical Specifications

What Can This BMS Be Used For?

This multi-cell BMS board is ideal for hobbyists, engineers, and makers building or repairing lithium battery packs for:

• Electric bikes and scooters
• Power tool battery packs
• RC vehicles and drones
• Solar energy storage systems
• Portable power stations and DIY battery projects

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Learn more: EPA guidance on lithium-ion battery handling

Frequently Asked Questions

Q: Is this BMS protection board compatible with all 18650 lithium cell chemistries?

A: This BMS protection board is specifically designed for LMO (Lithium Manganese Oxide) and ternary lithium (NMC) 18650 cells. It is not recommended for LiFePO4 cells, which have different voltage thresholds. Always verify your cell chemistry before installation.

Q: Can I use this board for both 4S and 7S battery packs?

A: Yes! This BMS supports 4S (16.8V), 5S (21V), 6S (25.2V), and 7S (29.4V) configurations, making it one of the most flexible protection boards available for 18650 lithium packs. Ensure your charger voltage matches the configuration you are using.

Q: What happens if there is a short circuit?

A: The board automatically detects a short-circuit event and cuts power to protect the cells and connected devices. After a built-in safety delay, the protection resets automatically — no manual intervention required.

Q: Does the board come with batteries or a charger?

A: No. This listing includes only the BMS protection board (1 set). Batteries and chargers are sold separately. Please ensure your charger voltage matches your chosen cell configuration (4S/5S/6S/7S).

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.