USB LiIon/LiPoly charger [v1.2]

A reliable USB-powered charger for single-cell 3.7V lithium-ion and lithium-polymer batteries. Based on the MCP73833 charging IC, it connects to any USB port or wall adapter via mini-B connector and provides safe, intelligent charging with visual status feedback.

Three indicator LEDs show power, charging status, and completion at a glance. Dual JST connectors let you keep the battery connected while powering your project—no need to disconnect for charging.

Key Features

• 3-Stage Charging – Preconditioning, constant-current fast charge, and constant-voltage trickle charge for optimal battery health
• 500mA Default Current – Adjustable from 100mA to 1000mA by soldering a through-hole resistor
• Dual JST Connectors – Separate ports for battery and load system allow pass-through operation
• Triple LED Indicators – Power, charging, and charge complete status at a glance
• Thermistor Support – 10K resistor installed; replace with NTC thermistor for temperature monitoring at high charge rates
• Breakout Pins – 0.1" (2.54mm) headers for battery, DC, and status LEDs

Specifications

• Input – 5V via USB mini-B
• Battery Compatibility – Single-cell 3.7V/4.2V Li-Ion or LiPo
• Charge Current – 500mA default (100-1000mA adjustable)

Package Contents

• 1× USB LiIon/LiPoly Charger v1.2 (assembled and tested)
• 1× 2-pin JST cable