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Dual 18650 Battery Charger - 3.7V Li-ion USB Universal Charger

Specification	Details
Compatible Battery	18650 Li-ion (Rechargeable)
Input Voltage	5V DC (Standard USB)
Output Voltage	3.7V - 4.2V DC
Charging Slots	2 Independent Slots
Charging Current	~500mA to 1000mA (Total)
Indicator	LED Status (Red/Green or Red/Blue)

Price

🚚 Ships within 24 Hours
📦 Pan India Delivery

₹ 144.07

(Tax included)

Barcode: 6431060

Product Description

The 3.7V Dual 18650 Rechargeable Lithium Battery Charger is a compact and efficient charging station designed for the most common high-capacity cylindrical Li-ion cells. Featuring two independent charging bays, this module allows you to charge one or two 18650 batteries simultaneously. The charger is powered via a standard USB interface, making it highly versatile for use with mobile phone adapters, power banks, or computer USB ports. Each slot is engineered with a spring-loaded slider to ensure a tight electrical connection with various lengths of 18650 cells, including both flat-top and button-top variants.

Key Features

Dual-Slot Independent Charging: Each bay operates autonomously, allowing you to charge batteries of different remaining capacities without affecting each other.
Smart LED Indicators: Provides instant visual feedback; typically turns Red during active charging and switches to Green (or Blue) once the battery reaches its full 4.2V capacity.
USB-Powered Portability: The 5V input allows for easy charging on the go, compatible with almost any modern DC power source.
Safety Protection Circuitry: Includes basic over-charge protection to prevent the lithium cells from exceeding their safe voltage limit, which is critical for battery longevity.
Universal 18650 Fit: The robust spring mechanism accommodates the slight size differences between protected and unprotected 18650 cells.

Technical Details

Plug Type: USB (Cable included/integrated depending on variant).
Construction: Fire-retardant ABS plastic housing.
Termination Voltage: Precise 4.2V ± 1% cutoff.

Prototyping and Engineering Tips from Robogears

The "4.2V Full" Rule: While these batteries are labeled as "3.7V" (nominal voltage), a healthy, fully charged Li-ion battery should measure exactly 4.2V on a multimeter. If your charger stops at 4.1V, it is a safety feature to extend cycle life; if it goes above 4.25V, disconnect it immediately.
Polarity Check: CRITICAL: Most basic 18650 chargers do not have "Reverse Polarity Protection." Always ensure the positive (+) end of the battery (the end with the small indent or button) matches the (+) mark on the charger. Inserting them backward can cause the charger or the battery to overheat rapidly.
USB Power Source: For the fastest charging speeds, use a USB wall adapter rated for at least 2A (2000mA). If you plug the charger into a low-power laptop USB 2.0 port, the charging time will be significantly longer because the port cannot supply enough current for two cells.
Heat Monitoring: It is normal for the batteries to feel slightly warm during the bulk charging phase. However, if a battery becomes too hot to touch, the internal resistance of the cell may be too high (indicating an old or damaged battery), and it should be disposed of safely.
Avoid "Deep Discharge": To keep your 18650s healthy, try to recharge them before they drop below 3.0V. Standard chargers may sometimes fail to "wake up" a battery that has been drained down to 0V.

Package Includes

1 x 3.7V Dual 18650 Rechargeable Lithium Battery Charger

Disclaimer: Never leave lithium batteries charging unattended. Do not attempt to charge non-rechargeable batteries (like Alkaline or Zinc-Carbon) in this device. Ensure the charger is kept away from flammable materials and moisture. Use only with high-quality 18650 cells to ensure safety and performance.