Professional battery chargers, battery testers and engine troubleshooting and tuning tools aimed at the power sport, marine, automotive, light aircraft and industrial equipment industries. Adafruit Industries, Unique & fun DIY electronics and kits USB/DC Lithium Polymer battery charger 5-12V [3.7/4.2v cells] : ID 280 - Charge your single-cell lithium ion/polymer battery any which way you like with this board. Have a USB connection? No problem, just plug into the miniUSB connector. Only have a wall adapter? Any standard 2.1mm DC adapter which puts out.