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

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

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 LMO and Ternary (NMC) 18650 Li-ion cell configurations, this compact board provides active cell balancing, overcharge protection, over-discharge protection, and automatic short-circuit recovery — all in a single, space-saving PCB module. Made in Mainland China.

Key Features

• Wide Cell Configuration Support: Compatible with 4S, 5S, 6S, and 7S series 18650 lithium cell packs (charging voltages: 16.8V / 21V / 25.2V / 29.4V).
• Active Cell Balancing: 56mA balanced current keeps all cells at equal charge levels, extending overall pack lifespan.
• Overcharge Protection: Triggers at 4.25V ± 0.025V per cell, preventing dangerous overcharge conditions.
• Over-Discharge Protection: Activates at 2.7V ± 0.5V per cell to guard cells from deep discharge damage.
• 18A Continuous / 26A Instantaneous Current: Handles high-drain applications with a generous instantaneous upper-limit current of 26A.
• Short-Circuit Protection: Automatically detects short circuits and recovers after a safe delay — no manual reset required.
• Compact Form Factor: Measures just 60 × 40 × 6.0 mm, fitting neatly into custom battery enclosures and DIY power projects.
• Durable Construction: Built with a plastic and metal composite for reliable, long-term performance.

Technical Specifications

Ideal For

• DIY 18650 lithium battery pack builds
• E-bike, e-scooter, and power tool battery packs
• Custom power banks and portable energy storage
• RC vehicles and robotics battery management
• Solar energy storage and off-grid power projects

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Learn more: EPA guidance on lithium-ion battery handling

Frequently Asked Questions

Q: What lithium battery chemistries is this BMS Protection Board compatible with?

A: This BMS board is designed for LMO (Lithium Manganese Oxide) and Ternary (NMC — Nickel Manganese Cobalt) 18650 Li-ion cells. It supports 4S, 5S, 6S, and 7S series configurations with charging voltages of 16.8V, 21V, 25.2V, and 29.4V respectively.

Q: Does this BMS board come with batteries or a charger?

A: No — this package includes only the BMS Protection Board itself (1 set). Batteries and chargers are not included and must be purchased separately.

Q: How does the short-circuit protection work on this board?

A: The board automatically detects a short-circuit event and cuts power to protect your cells and connected devices. After a brief delay, it recovers automatically — no manual reset or intervention is needed, making it ideal for unattended or enclosed battery pack installations.

Q: What does "cell balancing" mean and why does it matter?

A: Cell balancing ensures that all cells in a series battery pack charge and discharge to the same voltage level. Without balancing, individual cells can become mismatched over time, reducing overall capacity and potentially shortening pack life. This board provides passive balancing at 56mA to keep your cells in sync during every charge cycle.

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.