2S Lithium Battery Charger Protection Module (BMS) – 8.4V 20A
This high-current 2S BMS module is designed for 2-cell lithium-ion or lithium-polymer battery packs (7.4V nominal, 8.4V fully charged). With a 20A discharge current capacity, it’s ideal for demanding applications such as RC vehicles, e-bikes, robotics, power tools, and high-drain DIY power banks.
🔧 Key Features
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Battery Configuration: 2S (2 cells in series)
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Nominal Voltage: 7.4V
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Max Charging Voltage: 8.4V (4.2V per cell)
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Discharge Current: Up to 20A
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Charging Current: Typically up to 10A
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Built-in Protections:
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Overcharge protection
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Over-discharge protection
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Overcurrent protection
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Short-circuit protection
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Optional cell balancing (depends on version)
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Heavy-duty MOSFETs for handling high current
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Compact PCB design suitable for DIY and commercial battery packs
📐 Technical Specifications
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Overcharge Protection: ~4.25V ± 0.05V per cell
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Over-discharge Protection: ~2.8V ± 0.1V per cell
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Overcurrent Protection: 20A (instantaneous limit up to ~50A depending on model)
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Short-circuit Protection: Yes (auto recovery or manual reset depending on model)
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Working Temperature: –40°C to +85°C
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Board Size: Approx. 50mm × 25mm × 3mm
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Wiring Type: Solder pad (B+, B–, B1, P+, P–)
🛠️ Connection Guide
🔌 Wiring Steps
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B– → Connect to the negative of Cell 1
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B1 → Connect to the point between Cell 1 and Cell 2
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B+ → Connect to the positive of Cell 2
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P+ → Connect to your charger/load positive terminal
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P– → Connect to your charger/load negative terminal
⚠️ Important Note: Always connect the battery terminals first before connecting the charger or load. Misconnection may damage the module.
✅ Applications
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High-drain 2S battery packs (7.4V)
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RC cars, drones, and robotics
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Electric scooters and DIY e-bikes
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Portable power tools and solar systems
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Power bank modules and backup batteries
💡 Advantages
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Supports high current (20A continuous) for powerful devices
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Built-in safety protections to extend battery life and user safety
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Compact design for easy integration
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Suitable for both charging and discharging protection






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