The 4S 30A Protection Board with Automatic Recovery is a high-performance BMS (Battery Management System) designed to protect 4-cell (4S) lithium-ion and lithium-polymer battery packs from overcharge, over-discharge, and overcurrent conditions. With a 30A continuous discharge rating and automatic recovery function, this board is engineered for high-drain applications including power tools, e-bikes, energy storage systems, and portable power stations where reliable battery safety and convenience are essential.
At the heart of the board is a BMS 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 30A, protecting against short circuits and excessive loads.
The automatic recovery function is a key feature of this BMS. After a protection event (such as over-discharge or overcurrent), the board automatically restores output once the fault condition is removed — for example, when the load is disconnected or the battery is recharged. This eliminates the need for manual reset and ensures continuous, hassle-free operation.
The 4S configuration means the board manages four cells in series, balancing the voltage across all four 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 30A continuous rating makes this board suitable for high-power applications such as power tools, e-bikes, electric scooters, and energy storage systems. This is a significant step up from standard 4S boards that typically max out at 10A–20A, filling an important gap for high-current 4S applications.
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-, BM1, BM2, BM3 (mid-points), P+, and P- pads for battery and output connections.
Important Note: This BMS is designed for 4S (4-cell) 14.8V/16.8V lithium battery packs with a maximum continuous current of 30A. For higher-current applications, a BMS with a higher current rating should be used. Always verify the voltage and current ratings match your application before installation. Ensure all wiring and connections are rated for the maximum current your application will draw.
Whether you are building a high-power 4S battery pack for a power tool, assembling an e-bike battery, or adding safety protection to an energy storage system, the 4S 30A Protection Board with Automatic Recovery provides a reliable, high-power solution. It is suitable for individual makers, engineers, and businesses purchasing in bulk for product development or educational programs.
Features
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4S quad-cell protection — Manages four cells in series with cell balancing
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30A continuous discharge — High-power capability for demanding applications
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Automatic recovery function — Automatically restores output after fault removal
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Balance function — Ensures even charge and discharge across all four cells
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Comprehensive protection — Overcharge, over-discharge, and overcurrent protection
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Solder pad design — Supports both direct soldering and spot welding
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Compact PCB design — Sized for high-power battery packs
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Wide application range — Power tools, e-bikes, energy storage, portable power stations
Technical Specifications
| # | Parameter | Specification |
|---|---|---|
| 1 | Compatible Battery | 4S 14.8V lithium-ion / lithium-polymer |
| 2 | Full Charge Voltage | 16.8V |
| 3 | Continuous Discharge Current | 30A |
| 4 | Overcharge Protection Voltage | ~4.25V – 4.3V per cell |
| 5 | Over-discharge Protection Voltage | ~2.5V – 3.0V per cell |
| 6 | Automatic Recovery | Yes |
| 7 | Balance Function | Yes |
| 8 | Connection Type | Solder pads (spot welding supported) |
