If you need to charge LiPo batteries, this simple charger will do just that, and do it fast! The SparkFun USB LiPo Charger is a basic charging circuit that allows you to charge 3.7V LiPo cells at a rate of 500mA or 100mA. It is designed to charge single-cell Li-Ion or Li-Polymer batteries. The board incorporates a charging circuit, status LED, selectable solder jumper for 500mA or 100mA charging current, external LED footprint, USB input, two pre-installed JST connectors for SYS OUT and BATT IN, and (back by popular demand) a barrel jack connector. There is also a ‘SYS OUT’ with a pre-installed JST connector which allows you to connect the charging circuit directly to your project so you don’t need to disconnect the charger each time you want to use it.