Nitecore UM4 Charger

The Nitecore UM4 is an intelligent, four-slot USB battery charger that supports Quick Charge (QC) 2.0 and can charge a wide array of rechargeable battery types. Each slot is independently controlled, allowing you to charge different batteries simultaneously.
Specifications
Input: DC 5V/2A or 9V/2A, 18W (Max).
Output Voltage: 4.35V ±1% / 4.2V ±1% / 3.7V ±1% / 1.48V ±1%.

Output Current:
QC Mode: 1,500mA x 1, 1,500mA x 2, or 750mA x 4.
Standard Mode: 1,500mA x 1, 1,000mA x 2, or 500mA x 4.
Compatible Batteries: The UM4 supports various IMR, Li-ion, LiFePO4, Ni-MH, and Ni-Cd battery sizes, including common types like 18650, 21700, AA, and AAA.
Dimensions: 159mm x 107mm x 41mm.
Weight: 232.8g.

Key features
Intelligent charging: The charger automatically detects battery type and capacity to apply the optimal charging strategy.
Real-time LCD display: An informative display shows details like voltage, current, and charging progress.
Manual control: Users have the option to manually adjust charging current and cut-off voltage for certain batteries.
Independent slots: Each of the four slots operates independently.
Quick Charge 2.0: Supports faster charging speeds with compatible power sources.
Safety features: Includes various protections such as reverse polarity and short circuit prevention, along with features for activating over-discharged batteries and restoring IMR batteries.
Durable construction: Built with fire-retardant materials and designed for efficient heat dissipation.

• Use only rechargeable batteries: Never attempt to charge non-rechargeable cells, such as alkaline, CR123A, or CR2 batteries.
• Inspect batteries before charging: Do not charge any battery that shows damage, such as swelling, dents, or tears in the outer wrapper.
• Check the power source: Use only the official Nitecore cable and a compatible USB adapter (QC 2.0 is recommended for maximum speeds). Unofficial or damaged cables can cause overheating and other issues.
• Charge in a safe location: Always charge batteries on a non-flammable, fireproof surface. Do not leave the charger unattended and unplug it when not in use.
• Keep away from heat and moisture: Operate the charger in a well-ventilated area away from direct sunlight, open flames, and high humidity.
• Avoid misuse: Do not short-circuit the batteries or the charger. Never disassemble or modify the device. 

Safety features of the UM4
Overtime charging protection: The charger automatically stops charging any slot that exceeds 20 hours to prevent overheating from faulty batteries.
Reverse polarity and short-circuit protection: If you insert a battery incorrectly or if there’s a short circuit, the LCD screen will display “EE EE,” and the charger will not operate.
Over-discharged battery restoration: The UM4 can attempt to restore depleted IMR and Li-ion batteries. For over-discharged IMR batteries, the reverse polarity protection is temporarily disabled during restoration, so you must ensure correct polarity.
Temperature regulation: A built-in system protects the charger from overheating during the charging process.
Automatic internal resistance detection: The charger displays a battery’s health as “Good” or “Poor,” indicating when a cell may need to be replaced.

Operating instructions
After connecting the charger to a power source and inserting batteries with correct polarity, the UM4 automatically detects and begins charging standard 3.7V Li-ion and Ni-MH/Ni-Cd batteries. For LiFePO4 and 3.8V Li-ion batteries, manual adjustment of voltage is needed using the C and V buttons. You can also adjust the charging current in 100mA increments. The LCD screen shows real-time information. Charging stops automatically when complete.