2S 3A BMS Protection Board for 7.4V Li-ion and Li-Po Batteries

7.4V Battery Management Module with Overcharge, Over-Discharge and Short Circuit Protection

The 2S 3A BMS Protection Board is a compact electronic protection module designed for battery packs consisting of two lithium-ion or lithium-polymer cells connected in series (Li-ion / Li-Po). It is suitable for 7.4V nominal battery packs with a maximum fully charged voltage of 8.4V.

The module provides multiple protection functions to help prevent battery damage during operation. Its integrated electronics monitor cell voltage and disconnect the circuit under potentially unsafe conditions, including overcharging, excessive discharging, overcurrent and short circuits.

With a recommended continuous discharge current of up to 3A and a peak current of up to 5A, this protection board is suitable for compact battery packs, portable devices, DIY electronics and various applications powered by two lithium cells.

Its compact design and low standby power consumption make it a practical choice for battery systems where space efficiency and reliable protection are important.

Key Features:

• Designed for 2S Li-ion and Li-Po battery packs.

• 7.4V nominal battery voltage.

• 8.4V maximum fully charged battery voltage.

• Overcharge protection.

• Over-discharge protection.

• Overcurrent protection.

• Short-circuit protection.

• Continuous discharge current up to 3A.

• Peak current up to 5A.

• Very low standby power consumption.

• Compact design with MOSFET power transistors.

Suitable Applications:

• Battery packs using two 18650 or 21700 cells.

• Portable electronic devices.

• DIY rechargeable battery projects.

• Power supplies for small electrical equipment.

• LED lighting systems compatible with 2S battery packs.

• Portable and autonomous electronic systems.

• Assembly and repair of lithium-ion battery packs.

Technical Specifications:

• Type: BMS Battery Protection Board

• Configuration: 2S (2 cells connected in series)

• Compatible Batteries: Li-ion / Li-Po

• Nominal Voltage: 7.4V

• Maximum Battery Voltage: 8.4V

• Recommended Charging Voltage: 8.4V DC

• Maximum Continuous Discharge Current: 3A

• Maximum Peak Current: 5A

• Overcharge Protection: Approximately 4.25–4.35V per cell

• Over-discharge Protection: Approximately 2.3–3.0V per cell

• Protection Functions: Overcharge, over-discharge, overcurrent and short circuit

• Power Components: MOSFET transistors

• Standby Current: Less than 3µA (according to supplied specifications)

• Operating Temperature: -40°C to +50°C

• Storage Temperature: -40°C to +80°C

Board Connection Guide:

• B+ – Positive terminal of the complete battery pack.

• B- – Negative terminal of the complete battery pack.

• BM / MB – Midpoint connection between the two series-connected battery cells.

• P+ – Positive output for connecting the load and charger.

• P- – Negative output for connecting the load and charger.

Important Usage Information:

This is a BMS protection module, not a standalone battery charger. Use a dedicated CC/CV charger designed for 2S Li-ion/Li-Po battery packs, with a final charging voltage of 8.4V. Do not directly apply 9V to the battery pack or protection board without appropriate voltage regulation and current limiting.

During initial installation, the board may remain in a protection or standby state. Some versions require brief activation by applying a suitable charging voltage to the P+ and P- terminals.

Always use compatible battery cells and follow the correct wiring configuration. Check the B+, B-, BM, P+ and P- terminal positions on the actual board before installation. The presence of a BM connection alone does not confirm that the board supports active cell balancing.