3S 11.1V 12.6V 18650 Lithium and LiPo Battery Equalizer Balancer Board

3S 11.1V 12.6V 18650 Lithium and LiPo Battery Equalizer Balancer Board is a compact 3-series (3S 11.1V nominal / 12.6V full charge) cell voltage equalizer module engineered to keep all three cells in a 3S 18650 lithium-ion or lithium-polymer battery pack balanced during charging and operation. By equalizing individual cell voltages across `B-`, `B1`, `B2`, and `B3` (`B+`), it prevents cell divergence, maximizes usable pack capacity, and extends the cycle life of 12V lithium battery packs.

Key Features:

• Dedicated 3S (11.1V / 12.6V) Cell Equalization: Balances all 3 series cell groups in 11.1V/12.6V 18650 and LiPo packs so no single cell overcharges early or limits pack capacity.
• Compatible with All Non-Balanced 3S BMS Boards: Connects in parallel with the cell sense taps (`B-`, `B1`, `B2`, `B+`) of any 3S 4A, 10A, 20A, or 25A BMS protection board.
• 66mA Precision 4.20V Shunt / Equalizer Channels: Activates precisely at 4.20V per cell during charging (or transfers charge on inductive variants) to hold topped-up cells steady while lower cells finish charging.
• Ultra-Low Idle Consumption: Draws virtually zero current during normal battery discharge below 4.15V/cell.
• Featherweight Slim Footprint: Easily slips under PVC heat-shrink wrap alongside three 18650 cells.

Technical Specifications:

• Supported Pack Configuration: 3S (3 Series 3.7V Li-ion / 18650 / LiPo Cells — 11.1V Nominal / 12.6V Max)
• Single-Cell Balance Voltage: 4.20V DC per cell
• Balance Current: 66 mA per cell (Passive Shunt) / Up to 1.2A (Inductive Variant)
• Voltage Balance Accuracy: Within ± 0.03V (30 mV)
• Quiescent Standby Current: < 10 µA (Below 4.15V/cell)
• Operating Temperature Range: -20°C to +70°C

Mechanical Specifications:

• PCB Material: FR-4 Double-Sided Fiberglass PCB
• Terminals: 4 × Solder Pads (`B-`, `B1`, `B2`, `B3`/`B+`)

Dimensions:

• Length: ~26 mm to 42 mm
• Width: ~15 mm to 18 mm
• Thickness: ~2.5 mm
• Weight: ~3 g

Pinout and Wiring:

• B- (0V): Connect to Cell 1 Negative (Pack Negative).
• B1 (3.7V): Connect to the junction between Cell 1+ and Cell 2-.
• B2 (7.4V): Connect to the junction between Cell 2+ and Cell 3-.
• B3 / B+ (11.1V/12.6V): Connect to Cell 3 Positive (Pack Positive).
• Usage Note: Always pair with a 3S BMS protection board (`HX-3S-FL10A`, `3S 20A`, etc.) for over-discharge and short-circuit protection.

Datasheet Reference:

• Circuit Architecture: 3-Channel Precision 4.20V Cell Voltage Equalizer Network

Commonly Used in:

• 3S 11.1V / 12.6V 18650 Solar, UPS, and Router Battery Packs
• 12V Cordless Screwdriver & Drill 3-Cell Packs
• 3S LiPo RC Car, Boat, and Drone Battery Maintenance
• Robotics & Portable Instrumentation Packs

Applications:

• Adds cell-balancing capability to economical 3S BMS boards (`HX-3S-FL10A` 10A or `3S 20A`) that do not include onboard balance resistors.
• Prevents one cell in a 3S pack from drifting higher than the others over repeated charge/discharge cycles.
• Ensures full 12.6V charge termination across all three cells.

Equivalent Models:

• 4S 14.8V Li-ion Balancer Board: 4-cell (14.8V/16.8V) 66mA passive balancer board (`PID 2145`).
• 3S 12V 25A 18650 Lithium Battery Protection Board: All-in-one 3S 25A BMS board with built-in passive balancing (`PID 2701`).

Package Includes:

• 1 × 3S 11.1V 12.6V 18650 Lithium and LiPo Battery Equalizer Balancer Board