The 4S 1.2A Active Balancer Equalizer is a high-efficiency battery balancing module designed specifically for 12V battery packs using LFP (LiFePO4) and NCM (Li-ion) cells. This active balance board continuously monitors the voltage difference between adjacent cells and intelligently transfers energy from higher-voltage cells to lower-voltage cells, ensuring optimal voltage consistency across the entire battery pack.

Unlike passive balancers that dissipate excess energy as heat, this active balancer improves overall battery efficiency, extends battery lifespan, and enhances charge–discharge performance. It is ideal for applications such as solar energy storage systems, electric vehicles, backup power systems, DIY battery packs, inverters, UPS systems, and off-grid energy projects. The balancer must be used together with a BMS protection board to ensure complete battery safety.

Designed for batteries under 30Ah capacity, this 4S active equalizer provides fast balancing response with up to 1.2A maximum balance current, making it suitable for maintaining healthy battery packs in both professional and DIY environments.

Features:

• Active energy transfer balancing for improved battery efficiency

• Designed for 4S 12V battery packs using Li-ion (NCM) and LiFePO4 (LFP) cells

• Automatically detects voltage differences between adjacent cells

• High balance accuracy of approximately 30mV

• Starts balancing when voltage difference exceeds 0.1V

• Stops balancing when voltage difference drops below 0.03V

• Maximum balance current up to 1.2A for fast equalization

• Low static working current for minimal energy consumption

• Improves battery lifespan, safety, and performance

• Compact size suitable for battery enclosures and DIY builds

• LED balance indicator for real-time working status

• Requires external BMS for full protection functionality

Specifications:

• Battery Configuration: 4S (12V battery pack)

• Applicable Battery Types:

  • NCM (Li-ion)

  • LFP (LiFePO4)

  • Not compatible with LTO batteries

• Single Cell Voltage Range: 3.0V – 4.2V

• Recommended Battery Capacity: 5Ah-100Ah

• Voltage Balance Accuracy: 30mV (typical, adjacent cells)

• Balance Trigger Voltage Difference: ≥ 0.1V

• Balance Stop Voltage Difference: ≤ 0.03V

• Balance Current:

  • 0.5A at 0.1V difference

  • Up to 1.2A at ≥ 0.2V difference

• Under-voltage Dormant Mode: Activated below 0.03V difference

• Static Working Current: 0.01mA

• Indicator Status: LED balance indicator

• Accessories: 30cm 22AWG terminal wire

• Dimensions: 2.16 × 0.90 × 0.25 inches

Balance Indicator Status:

• Balance indicator ON: Active balancing in progress

• Balance indicator OFF: Balancer in sleep or standby mode

• Balance indicator flashing: Cell voltage drop detected or circuit fault indication

How to Use:

• Install the balancer in parallel with the battery pack cells

• Ensure a compatible BMS protection board is already installed

• Connect balance wires carefully according to the wiring sequence

• Insert the balance cable obliquely, starting from the B- pin

• Verify correct voltage levels before powering the system

• Monitor LED indicator to confirm balancing operation

• Use only within specified voltage and capacity limits

• Suitable for long-term installation in battery storage systems

• Ensure proper insulation and secure mounting inside battery enclosure

Wiring Instructions:

• B-: Total negative pole of the battery pack (negative of the first cell)

• B1: Positive pole of the first battery cell

• B2: Positive pole of the second battery cell

• B3: Positive pole of the third battery cell

• B4: Positive pole of the fourth battery cell

• B5 and above: Used only for higher series configurations (not applicable for 4S)

Package Includes:

• 1 × 4S Active Balance PCB

• 1 × 5-pin balance cable

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