I’ve just posted this on the Adafruit forum, but it deserves to be here as well:
I purchased the Gemma (v2) recently and have gotten it to work (though not without some difficulty with drivers). I have a Li-Poly battery hooked up, but it doesn’t seem to be charging. I’ve reviewed the schematic (see http://www.arduino.cc/en/uploads/Main/arduino-gemma-schematic.pdf), and the only path for charging the battery seems to be through the series circuit including USB port, forward-biased D2, and reverse-biased D3. Therefore the charging current is primarily limited by the reverse leakage current of D3 (Schottky diode), which at the typical operating voltages present is likely only in the micro-ampere range. Such a low current would take many 1000’s of hours to recharge even a very small Li-Poly battery.
The description of the Gemma on Arduino’s site http://www.arduino.cc/en/Main/ArduinoGemma states that the device will charge the battery when the power switch is in the OFF (CHG) position, but perhaps this is for a previous version of the Gemma? There is also mention of an LED to indicate charging status, but this is not evident in the product photos or in the schematic. What are the suggested work-arounds?