SLCT 4S-6235 4S 14.8V 20A NMC Lithium-Ion Battery Protection BMS

1. Product Overview

The Lik-4S-6235 is a compact 4S 20A battery-management and protection board designed for NMC lithium-ion battery packs containing four cells or parallel cell groups connected in series.

A 4S NMC lithium-ion pack has a nominal voltage of approximately 14.4V–14.8V and reaches 16.8V when fully charged.

The BMS monitors the four series-connected cell groups and helps protect the battery against unsafe charging, excessive discharge, overcurrent and short-circuit conditions.

This model uses a common-port arrangement, with the charger and load sharing the C−/P− negative connection. A metal cover protects the electronic components and helps distribute heat.

2. Technical Specifications

Protection thresholds, balancing current, continuous charge-current rating and recovery-delay values should be confirmed from the seller or manufacturer before use in a critical application.

3. Visible Connections

Always verify the supplied wiring sequence before installation. Do not identify balance wires only by their colours or physical positions.

4. Protection Functions

The Lik-4S-6235 BMS is intended to provide essential protection for compatible 4S NMC lithium-ion battery packs, including:

• Individual cell-group voltage monitoring
• Overcharge protection
• Over-discharge protection
• Discharge-overcurrent protection
• Short-circuit protection
• Charge and discharge control through onboard MOSFETs
• Temperature monitoring through the external sensor
• Recovery after supported protection events

Cell balancing is not confirmed from the visible markings and should be verified before advertising the board as a balancing BMS.

5. Suitable Applications

This BMS may be suitable for compatible 4S NMC lithium-ion battery packs used in:

• Rechargeable LED lights
• Portable electronic equipment
• Robotics projects
• DIY battery packs
• Small power-backup systems
• Battery-powered instruments
• Toys and hobby equipment
• Portable speakers
• Electronic repair projects
• Compatible 14.8V lithium-ion battery packs

The equipment’s continuous operating current and startup current must remain within the verified capability of the BMS, battery cells, wiring and connectors.

6. Battery and Charger Compatibility

Use this BMS only when:

• The battery contains exactly four series-connected lithium-ion cell groups.
• Each cell group has a nominal voltage of 3.6V or 3.7V.
• Each cell group has a maximum charging voltage of 4.2V.
• The pack’s nominal voltage is approximately 14.4V–14.8V.
• The charger is designed specifically for a 4S lithium-ion battery.
• The charger’s maximum output voltage does not exceed 16.8V.
• All four cell groups are at closely matched voltages before installation.
• The battery cells can safely provide the required current.
• The equipment’s operating and peak current remain within the verified system limits.

Do not use this BMS with 4S LiFePO₄ cells. LiFePO₄ batteries require different charging and protection-voltage thresholds.

7. Installation Guidance

• Measure the voltage of all four cell groups before installation.
• Confirm that the cell-group voltages are closely matched.
• Connect B− to the battery pack’s main negative terminal.
• Connect the balance wires sequentially to the correct cell-group junctions.
• Connect the final positive sensing wire to battery positive as specified.
• Connect the charger and load negative to C−/P−.
• Connect the charger and load positive directly to battery positive unless the supplied wiring diagram states otherwise.
• Position the temperature sensor securely against a representative cell or thermal hotspot.
• Verify the voltage between every consecutive balance wire before inserting the connector.
• Use correctly sized cables and connectors for the expected current.
• Install a suitable fuse close to the battery’s positive terminal.
• Insulate every exposed terminal and conductive surface.
• Mount the BMS where it cannot contact nickel strips, busbars or a metal enclosure.

Incorrect balance-wire order can permanently damage the BMS.

8. Important Current-Rating Note

The advertised 20A BMS rating does not increase the current capability of the battery cells.

The safe operating current of the completed battery pack is determined by its lowest-rated component, including:

• Battery cells
• BMS
• Nickel strips or busbars
• Power cables
• Connectors
• Fuse
• Charger
• Connected load

Motors and other inductive loads may draw startup current considerably higher than their normal operating current. Confirm both continuous and peak-current requirements before using this BMS.

9. Safety Information

• Use only with a compatible 4S NMC lithium-ion battery pack.
• Use only a charger with a verified 16.8V maximum output.
• Never reverse the battery polarity.
• Never short B−, B+, C−/P− or the battery terminals.
• Do not connect the balance wires in the wrong order.
• Verify every sensing voltage before plugging in the balance connector.
• Do not exceed the verified current rating.
• Use a correctly rated fuse, wiring and connectors.
• Keep the PCB away from water, conductive dust and loose metal objects.
• Do not use a damaged, burnt, corroded or unusually hot board.
• Stop using the battery if any cell becomes swollen, overheated or abnormally unbalanced.
• Installation should be performed by someone familiar with lithium-ion battery wiring and safety.