USB LiIon/LiPoly charger (v1.2)

This MCP73833-based Li-Ion/LiPo charger uses USB mini-B and a 3-stage charging process, with three status LEDs and pass-through power via an extra JST connector. Fast charge is 500mA by default, adjustable from 100–1000mA. Adafruit LiPoly only.

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This Lithium Ion / Lithium Polymer battery charger is based on the MCP73833 and connects via USB mini-B, making it easy to power from a computer or a standard USB wall adapter. Charging is handled automatically in three stages: a preconditioning charge, followed by a constant-current fast charge, and then a constant-voltage trickle charge to keep the battery topped up.

By default, the fast-charge current is set to 500mA, but it can be adjusted anywhere from 100mA to 1000mA by soldering a through-hole resistor onto the board.

It’s a great choice for DIY projects thanks to the built-in three indicator LEDs: one for power, one for charging status, and one to show when charging is complete. You can also leave the battery connected and pass power through the extra JST connector using the included cable.

For use with Adafruit LiPoly batteries only. Other batteries may use different voltage, chemistry, polarity, or pinout.

Features

• Comes assembled and tested, includes a JST cable!
• 5V input via mini-B USB connector
• For charging single Lithium Ion/Lithium Polymer 3.7/4.2v batteries (not for older 3.6/4.1v cells)
• 500mA charge current, adjustable from 100mA to 1000mA by soldering in a resistor
• Separate JST connectors for battery and load system, so batteries don't have to be removed for charging
• Chip supports a 10K NTC thermistor which we have stuffed as a plain 10K. For people who require temperature monitors (using high charge rates), remove the 10K and solder in the thermistor in its place
• 0.1" (2.54mm) breakouts for the battery, DC, and status LEDs
• Free 2-pin JST cable included!
• Batteries and USB cable not included.