Charge and power your Pro Trinket with this LiIon/LiPoly Backpack Add-on board by Adafruit.
Adding a portable power supply to your Pro Trinket just got simple! Adafruit's new LiIon/LiPoly Backpack Add-On is soldered directly to the Pro Trinket and allows for easy integration and charging of 3.7v/4.2v Lithium Ion/Lithium Polymer batteries.
If you want to add a power switch to your system, the two 0.1" holes with a box around them are the battery output line. Cut the trace between the two holes, attach your switch leads, and voila, you can easily turn your Pro Trinket on or off.
Please keep in mind that ideally, this backpack is for use with the 3.3V version of the ProTrinket. This Backpack Add-on will regulate the 3.7V-4.2V battery voltage down to a usable 3.3V.
There are two LEDs - one red and one green. While charging, the red LED is lit. When the battery is fully charged and ready for use, the green LED turns on. Seriously, it could not get more easy.
Charging is performed in three stages: first a preconditioning charge, then a constant-current fast charge and finally a constant-voltage trickle charge to keep the battery topped-up. The charge current is 100mA by default, so it will work with any size battery and USB port. If you want you can easily change it over to 500mA mode by soldering closed the jumper on the bottom, for when you'll only be charging batteries with 500mAh size or larger.
For use with 3.7V/4.2V LiIon/LiPoly batteries only! Other batteries may have different voltage, chemistry, polarity or pinout.
Batteries and Pro Trinket not included.