The M-101A is a compact, single-slot smart charger designed specifically for 3.7V lithium-ion batteries, most notably the standard 18650 form factor. It features a built-in AC power cord, eliminating the need for an external wall adapter or USB cable. The charger uses an internal control circuit to manage the charging cycle, safely restoring power to high-capacity cells used in flashlights, power banks, and electronic projects.

Specifications

• Model: M-101A
• Input Voltage: 100V – 240V AC, 47 – 63Hz (Universal global voltage)
• Output Voltage: 3.7V – 4.2V DC
• Charging Current: 1000mA (1A)
• Supported Battery Types: Lithium-ion (Li-ion) 3.7V nominal cells
• Supported Sizes: 18650 (Standard), along with other similar length 3.7V cylindrical cells (e.g., 16340, 14500 if physical contact fits)
• Plug Type: Attached AC power cable

Features

• All-In-One Design: The integrated AC mains cable plugs directly into standard wall sockets, making it a self-contained unit that is highly portable.
• Smart LED Indicator: Provides immediate visual feedback on the charging state:
  • Red Light: Active charging mode.
  • Green/Blue Light: Standby, no battery inserted, or charging cycle complete (fully charged).
• Spring-Loaded Slider Slot: The negative terminal features a heavy-duty spring tension slider that secures different battery lengths firmly against the contact points.
• Automatic Cut-off: Built-in overcharge protection stops delivering current once the cell reaches its upper safety threshold of approximately 4.2V, preventing thermal runaway and preserving battery health.

Safe Operating Principles

Lithium-ion cells require a strict CC/CV (Constant Current / Constant Volume) charging profile. The M-101A automates this process:

1. Constant Current Phase: Delivers a steady 1000mA stream to quickly elevate the voltage of a depleted cell.
2. Constant Voltage Phase: As the cell reaches its capacity limit near 4.2V, the charger maintains the voltage while gradually reducing the current until the battery is safely saturated, triggering the LED status switch.

Common Applications

• Vape & Flashlight Maintenance: Recharging high-drain 18650 cells used in heavy-duty LED torches, laser pointers, and portable equipment.
• Electronics Prototyping: Keeping battery stocks prepared for Arduino, Raspberry Pi, or robotics projects powered by lithium power shields.
• Emergency Kit Prep: A straightforward backup charger for survival gear and solar-battery emergency banks.

Usage & Safety Tips

• Observe Polarity: Always match the positive (+) and negative (-) signs on the battery with the markings molded inside the charger slot. Inserting a battery backwards can damage both the cell and the charging circuitry.
• Unattended Charging: Never leave lithium-ion batteries charging completely unattended overnight or on flammable surfaces like carpets or bedding.
• 3.7V Batteries Only: This device is explicitly engineered for 3.7V/4.2V Lithium-ion chemistry. Do not attempt to charge 1.2V NiMH/NiCd rechargeables (like standard AA/AAA) or non-rechargeable alkaline cells, as they can leak or explode.
• Temperature Warning: It is normal for the charger and battery to feel slightly warm during the 1000mA fast-charge cycle. However, if either becomes uncomfortably hot to the touch, unplug the unit immediately.