4S 40A BMS 18650 Lithium Battery Protection Board – 14.8V/16.8V Battery Management System

4S 40A BMS 18650 Lithium Battery Protection Board – 16.8V Battery Management Module

The 4S 40A BMS (Battery Management System) Protection Board is designed to protect and manage 4-cell (4S) 18650 lithium-ion battery packs. It safeguards the battery against overcharging, over-discharging, overcurrent, and short circuits while ensuring balanced charging across all cells. Suitable for battery packs with a nominal voltage of 14.8V and a fully charged voltage of 16.8V, this BMS board is widely used in electric bicycles, solar energy storage, portable power stations, DIY battery packs, and backup power systems.

Specifications:

• Battery Configuration: 4S (4 Cells in Series)
• Compatible Battery Type: 18650 Lithium-ion / Li-ion Cells
• Nominal Battery Voltage: 14.8V
• Fully Charged Voltage: 16.8V
• Continuous Discharge Current: 40A
• Charging Method: CC/CV (Constant Current / Constant Voltage)
• Balancing Function: Yes
• Overcharge Protection: Supported
• Over-discharge Protection: Supported
• Overcurrent Protection: Supported
• Short Circuit Protection: Supported
• PCB Material: FR-4
• Mounting Type: PCB Module
• Dimensions: 46 x 60 x 3.4 mm

Typical Package Dimensions

• Length: 60–65 mm
• Width: 45–48 mm
• Thickness (PCB + Components): 3–5 mm
• Mounting Hole Diameter (if provided): 3.0–3.5 mm
• PCB Thickness: 1.6 mm
• Weight: 20–30 g

Key features and benefits:

• Supports 4S (4-cell) lithium-ion battery packs
• 40A continuous discharge capability
• Built-in cell balancing function
• Overcharge protection
• Over-discharge protection
• Overcurrent protection
• Short circuit protection
• Compact PCB design with high-current MOSFETs
• Suitable for 18650 and compatible lithium-ion cells

Terminal Connections

• B- : Battery Pack Negative
• B1 : Cell 1 Positive
• B2 : Cell 2 Positive
• B3 : Cell 3 Positive
• B+ : Battery Pack Positive
• P+ : Charge/Discharge Positive
• P- : Charge/Discharge Negative

Applications:

• DIY 18650 battery packs
• Electric bicycles and scooters
• Portable power stations
• Solar energy storage systems
• UPS battery packs
• Emergency lighting systems
• Robotics and RC projects
• Rechargeable power banks

Frequently Asked Questions (FAQ):

Q: Can I use this BMS with four 18650 cells connected in series?
A: Yes, this board is specifically designed for 4S (four-cell series) lithium-ion battery packs.

Q: Does this BMS provide cell balancing?
A: Yes, it includes a balancing function to help maintain equal voltage across all four cells during charging.

Q: Is this suitable for LiFePO4 batteries?
A: No. This BMS is designed for standard 3.7V lithium-ion cells (4.2V full charge). It should not be used with LiFePO4 batteries unless explicitly specified.

Q: Can I use this board for a 16.8V battery pack?
A: Yes. A fully charged 4S lithium-ion battery pack reaches 16.8V, making this BMS suitable for that application.

Q: Can it continuously supply 40A?
A: It is rated for up to 40A continuous discharge under appropriate cooling and operating conditions.

Q: Does this board protect against short circuits?
A: Yes, it includes built-in short circuit protection to help safeguard the battery pack and connected load.

Q: Can I use this BMS for an electric bicycle or scooter?
A: Yes, provided your battery pack configuration is 4S lithium-ion and the operating current is within the board's specifications.

Q: What should I check before purchasing this BMS?
A: Verify your battery chemistry, ensure your pack consists of four lithium-ion cells in series (4S), and confirm that your load current does not exceed the board's rated capacity.

Package Includes:

*Image shown is a representation only.

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