CN3761 Solar Lithium Battery Charger Module

Charging a lithium cell directly from a solar panel is riskier than charging from a stable wall adapter, since panel output voltage swings with sunlight intensity rather than staying fixed - this module is built specifically for that variability, accepting a 5V to 15V input range so it keeps charging correctly whether the panel is in full sun or partial shade rather than needing a tightly regulated input. The CN3761 chip handles the actual charge management, terminating at the standard 4.2V single-cell lithium full-charge voltage.

A soft-start feature ramps charging current up gradually rather than slamming full current into the battery the instant power arrives, reducing stress on both the panel connection and the battery itself. Two status LEDs (charging / full) give an at-a-glance read on state without needing a multimeter, and the default 1.2A charge current can be increased past 3A by modifying the current-set resistor for projects with larger cells and more available panel current.

Common uses are solar-powered garden lights, remote sensors, or IoT nodes charging a single lithium cell from a small panel, off-grid battery-backup projects, and any build wanting a purpose-built solar charge controller rather than adapting a generic USB charger circuit to variable panel voltage.