3S 25A BMS Lithium-Ion Battery Protection Board with Cell Balancing (11.1V / 12.6V)

The 3S 25A BMS (Battery Management System) bridges the gap between lightweight 10A boards and massive, bulky industrial controllers. Designed specifically for three-cell (3S) Lithium-Ion configurations—such as 18650 or 21700 arrays—it safely regulates a nominal 11.1V output (peaking at 12.6V). With a continuous discharge rating of 25 Amps, this board is engineered to handle the demanding electrical spikes of mid-sized DC motors, making it an exceptional choice for repairing cordless vacuums, upgrading RC vehicles, and building heavy-duty portable power stations.

Crucially, this specific model features integrated active cell balancing. In multi-cell packs, individual batteries inevitably charge at slightly different rates. Without balancing, one cell can overcharge while another remains depleted, drastically reducing the pack's lifespan. This board actively monitors each of the three tiers independently, bleeding off excess voltage from the fastest-charging cells through precision resistors. This ensures that every single cell hits exactly 4.2V simultaneously, guaranteeing maximum runtime and preserving the chemical health of your 18650s.

Key Features & Functional Advantages:

• 25A Continuous Discharge: Safely sustains up to 25 Amps of continuous current (roughly 300 Watts of power) and handles brief transient spikes up to 50A, providing massive headroom for demanding inductive loads.

• Active Cell Equalization: Built-in balancing circuitry equalizes the voltage across all three series cells during the final charging phase, capturing 100% of your pack's true storage capacity.

• Comprehensive Safety Suite: Acts as a vigilant gatekeeper, instantly severing the connection in the event of over-voltage (over-charging), under-voltage (deep discharging), extreme over-current, or a hard short-circuit.

• Low Heat Generation: Utilizes a bank of high-quality, ultra-low internal resistance MOSFETs to ensure minimal power loss and reduced thermal buildup during heavy operation.

• Compact & Flat Footprint: Designed to slide effortlessly alongside a standard 3-cell 18650 flat-pack or triangle-pack without requiring excessive modifications to your project enclosure.

Perfect For:

• Cordless Vacuum Rebuilds: The undisputed go-to replacement board for rebuilding or upgrading the dead 11.1V/14.4V internal battery packs in handheld vacuums and robotic floor sweepers.

• High-Wattage Portable Audio: Protects the internal lithium power supply inside custom-built, heavy-duty Bluetooth boomboxes and PA systems.

• Mid-Sized Robotics: Delivers rugged, unthrottled power to 12V-class robotic chassis utilizing multiple high-torque geared motors and heavy servos.

• DIY Power Banks & Lighting: An excellent controller for custom 12V power banks designed to drive high-wattage LED floodlights, camping arrays, and amateur radio equipment.

Technical Specifications:

• Configuration: 3S (3 Cells in Series)

• Supported Chemistry: Lithium-Ion (18650, 21700, etc.) with 3.7V nominal / 4.2V peak rating

• Nominal Pack Voltage: 11.1V

• Full Charge Voltage: 12.6V (Requires a dedicated 12.6V CC/CV lithium charger)

• Maximum Continuous Discharge Current: 25A

• Peak / Instantaneous Current: ~50A

• Overcharge Protection Threshold: 4.25V ±0.05V per cell

• Over-Discharge Cut-off Threshold: 2.5V ±0.05V per cell

• Balancing Current: ~42mA to 50mA per cell

• Approximate Dimensions: 56 mm x 45 mm x 3 mm

• Wiring Setup: Separate port or Same port (Verify specific manufacturer layout via included wiring diagram)

Ensure your order is placed by 2PM to guarantee next-day delivery! Our commitment to prompt service includes a 24-hour delivery system through our network of carriers, aimed at ensuring your package arrives right on schedule.

Please note, a delivery fee of €4.99 applies for orders under €50. For those in remote areas, be aware that our couriers may apply an extra surcharge. This additional fee helps cover the costs of transporting your items to harder-to-reach locations.