Description
2S 8A Lithium Battery Management System (BMS)
The 2S 8A BMS is a miniature protection circuit board designed specifically for 2-series (2S) Lithium-ion or Lithium-polymer battery packs. With a nominal voltage of 7.4V (8.4V fully charged), it is the ideal safety solution for small, compact electronics that require moderate power and reliable cell monitoring.
Technical Specifications
| Feature | Specification |
| Compatible Cells | 2-Series (7.4V nominal / 8.4V full) |
| Continuous Discharge | 8A |
| Instantaneous Current | Typically 12A–15A (Burst) |
| Charging Voltage | 8.4V (CC/CV) |
| Overcharge Threshold | 4.25V ± 0.05V |
| Over-discharge Threshold | 2.50V ± 0.1V |
| Balanced Charging | Integrated |
| Dimensions | Ultra-compact (typically ~35mm x 10mm) |
Key Functions & Protections
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Integrated Cell Balancing: Ensures that both cells in the 2S configuration charge to the exact same voltage. This prevents one cell from becoming over-stressed, significantly prolonging the lifespan of your battery pack.
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Safety Cut-offs: The board provides automatic protection against over-voltage (during charging) and under-voltage (during use). If a short circuit occurs, the BMS instantly severs the connection to prevent fire or damage to the cells.
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Compact Form Factor: Specifically designed for space-sensitive applications, making it perfect for integration into thin handheld devices or small project enclosures.
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Common Port Logic: Uses the same terminal points for both charging the pack and drawing power for the load, minimizing the number of wires required for your circuit.
Important Installation & Safety Guidelines
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Wiring Sequence (Critical): Always connect your wires in the exact order: 0V (B-), 3.7V (B1), and 7.4V (B+). Plugging in the balance connector while the pack is connected to a load can lead to an internal short, which will permanently destroy the BMS controller.
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Charger Requirements: This BMS requires a dedicated 8.4V (2S) Lithium charger using the CC/CV charging profile. Do not use an unregulated 9V or 12V power supply, as the BMS depends on a strict voltage limit to correctly terminate the charging cycle and balance the cells.
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Current Limitations: While rated for 8A continuous discharge, avoid running the board at this limit for extended periods if the BMS is in a sealed enclosure. The MOSFETs require at least a small amount of airflow to remain within their optimal operating temperature.
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Wire Gauge: Given the 8A rating, 22AWG or 24AWG wire is generally sufficient for your load connections.

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