The 2S 7.4V Lithium Battery Protection Board is a compact, essential safety module designed to protect 2-cell (2S) lithium-ion and lithium-polymer battery packs from overcharge, over-discharge, and overcurrent conditions. It is specifically engineered for battery packs with a nominal voltage of 7.4V and a full charge voltage of 8.4V, making it an indispensable component for DIY battery packs, power banks, portable electronics, and RC vehicles.
At the heart of the board is a BMS (Battery Management System) protection circuit that continuously monitors the voltage of each cell and the total pack current, disconnecting the load or charger if any parameter exceeds safe limits. This protects both the battery pack and your connected devices from damage, extending battery lifespan and ensuring safe operation.
The board provides three critical protection functions:
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Overcharge protection — Disconnects the charger when any cell voltage reaches approximately 4.25V to 4.3V, preventing damage from excessive charging.
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Over-discharge protection — Disconnects the load when any cell voltage drops to approximately 2.5V to 3.0V, preventing deep discharge that can permanently damage the battery.
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Overcurrent protection — Disconnects the output when current exceeds safe limits, protecting against short circuits and excessive loads.
The 2S configuration means the board manages two cells in series, balancing the voltage across both cells to ensure they charge and discharge evenly. This cell balancing function is critical for maintaining pack health and maximizing lifespan. Without proper balancing, one cell can become overcharged or over-discharged, leading to premature failure or safety hazards.
The board features a solder pad design that supports both direct soldering and spot welding. The exposed pads allow you to solder wires directly to the board, while also being compatible with spot-welded nickel strips for professional battery pack assembly. The board includes B+, B-, BM (mid-point), P+, and P- pads for battery and output connections.
The 2S Protection Board is widely used in DIY power banks, 18650 battery packs, portable speakers, RC vehicles, drone battery packs, solar garden lights, portable electronics, and any application where 2S lithium battery safety is critical.
Important Note: This protection board is designed for 2S (2-cell) 7.4V lithium battery packs. For other configurations, a different protection board or BMS should be used. Always verify the voltage and current ratings match your application before installation.
Whether you are building a custom 2S battery pack, assembling an 18650 pack for a portable device, or adding safety protection to an RC vehicle, the 2S 7.4V Lithium Battery Protection Board provides a reliable, cost-effective solution. It is suitable for individual makers, students, and businesses purchasing in bulk for product development or educational programs.
Features
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2S dual-cell protection — Manages two cells in series with cell balancing
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Comprehensive protection — Overcharge, over-discharge, and overcurrent protection
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Cell balancing function — Ensures even charge and discharge across both cells
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Solder pad design — Supports both direct soldering and spot welding
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Wide compatibility — Works with 18650, polymer, and prismatic lithium cells
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Compact PCB design — Sized for space-constrained battery packs
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Simple connection — B+/B-/BM for battery, P+/P- for protected output
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Wide application range — Power banks, RC vehicles, portable devices, DIY projects
Technical Specifications
| # | Parameter | Specification |
|---|---|---|
| 1 | Compatible Battery | 2S 7.4V lithium-ion / lithium-polymer |
| 2 | Full Charge Voltage | 8.4V |
| 3 | Overcharge Protection Voltage | ~4.25V – 4.3V per cell |
| 4 | Over-discharge Protection Voltage | ~2.5V – 3.0V per cell |
| 5 | Continuous Discharge Current | Variant dependent (typically 2A–5A) |
| 6 | Cell Balancing | Yes |
| 7 | Connection Type | Solder pads (spot welding supported) |
| 8 | Module Dimensions | Compact PCB for 18650/polymer cells |
