Name: 4S 20A 18650 Lithium Battery Protection Board (16.8V/14.8V)
Brand: Sun Cheong Computer Company Limited
SKU: 21PS001259
Price: 104.0 TWD
Availability: InStock

Short Product Description

Protect Your Power, Prolong Your Battery Life.
Stop worrying about overcharging or dangerous short circuits. Our premium 4S 20A BMS module is the essential brain for your custom 18650 battery packs. Whether you’re reviving a cordless tool, building a portable LED backup, or engineering a DIY power bank, this board provides the industrial-grade safeguards needed to ensure reliable and safe operation every time you power up.

Key Features

Precision Overcharge Protection: Automatically stops charging when any cell reaches 4.35V, preventing battery swelling and fire risks.
Deep Discharge Prevention: Cuts power when voltage drops to 2.3V, saving your cells from irreversible capacity loss.
20A Peak Performance: Handles high-torque startup currents for motors and power tools without tripping.
Ultra-Low Quiescent Drain: Consumes less than 30uA, ensuring your battery stays charged even during long periods of storage.
Short Circuit Recovery: Built-in protection that can be easily reset by applying a charging voltage to the module.
Compact Square Design: The 36mm form factor allows for seamless integration into portable devices and battery holders.

Full Product Description

Comprehensive Battery Management for 14.8V/16.8V Packs

Designed for 4-series (4S) lithium-ion configurations, this module manages the delicate balance of four 3.7V cells. It operates at a nominal 14.8V and reaches a full 16.8V charge capacity. Integrated with the high-precision BM3451 protection IC and MDU1515 low-resistance MOSFETs, it ensures maximum energy efficiency with minimal heat generation.

Why Your Project Needs This 4S BMS

Standard lithium cells are volatile if mismanaged. This board acts as a permanent guardian, monitoring individual cell voltages with $\pm 25\text{mV}$ accuracy. It doesn't just cut power; it manages the health of your energy storage to prevent premature cell death and hazardous thermal events.

Technical Specifications

Model: HX-4S-D20 / HXYP-4S-B20A
Compatible Battery: 3.7V Li-ion / 18650 / LiCoO2
Number of Cells: 4 (Connected in Series)
Charging Voltage: 16.8V - 17V
Max Working Current: 10A (Continuous)
Peak Instantaneous Current: 20A
Overcharge Voltage Range: 4.25V - 4.35V ± 0.05V
Over-discharge Voltage Range: 2.3V - 3.0V ± 0.05V
Static Current: Less than 30uA
Effective Life: >50,000 Hours
Internal Resistance: Less than 100mΩ
Dimensions: 36mm x 36mm x 3.6mm

Delivery Options

Local delivery within Hong Kong and in-store pickup.
Free shipping for orders of HK$400 or above; HK$35 shipping fee for orders below HK$400.
Shipped by SF Express, usually dispatched the same day for orders confirmed before 6:00 PM (Mon–Sat).
Estimated delivery time: 1–3 business days after dispatch (Hong Kong).
In-store pickup details (location and time) will be confirmed by email or phone message.
Delivery times are estimates and may be affected by weather or unforeseen circumstances.

FAQ Section

Q: Why is there no output voltage after I connected the batteries?
A: This is a standard safety feature. After wiring, you must connect a 16.8V charger to the P+ and P- terminals for 3-5 seconds to "activate" the board.

Q: Can I mix old and new 18650 batteries with this board?
A: We strongly advise against it. Always use 4 cells with identical capacity and internal resistance. A single "bad" cell will compromise the entire pack's performance.

Q: Does this work with LiFePO4 batteries?
A: No. This board is calibrated for 3.7V lithium-ion cells. LiFePO4 requires different voltage thresholds for safety.

Target Users / Applications

This module is perfect for low-power inverters, massager battery packs, LED lamp backup power supplies, solar street light battery systems, and security monitoring backup power. Note: Not suitable for high-power motors like the 775 series or high-wattage electric bicycles.