100mA charge current, adjustable to 500mA by soldering a jumper closedīatteries and Pro Trinket or ItsyBitsy not included.For charging single Lithium Ion/Lithium Polymer 3.7/4.2v batteries (not for older 3.6/4.1v cells).Uses the 5V input via Micro-B USB connector on the Pro Trinket or ItsyBitsy.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.įor use with Adafruit LiPoly/LiIon batteries only! Other batteries may have different voltage, chemistry, polarity or pinout. The charge current is 100mA by default, so it will work with any size battery and USB port. Carefully cut the trace between them with a hobby knife and replace with two wires from a switch like this slide switch, or this pushbutton one, for example.Ĭharging 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 two 0.1' holes with a box around them are the battery output line. If you want to add an On/Off switch, we also made that really easy. When the battery is fully charged and ready for use, the green LED turns on. There are two LEDs - one red and one green. Solder the backpack on with the extra long header so that it can still plug into a breadboard, or clip the long header leads short afterwards for a slim package. (Technically its overclocking but we've never seen that affect the microcontroller itself, AVRs are happy to overclock without complaint). However, many times, you can run a 5V microcontroller + accessories off of the ~4V from the LiPoly battery with no problem.

Ideally, this backpack is for use with the 3.3V Pro Trinkets & ItsyBitsy, so that the battery voltage (3.7V-4.2V) will get regulated down to 3.3V on the board.

Unplug the USB port and the microcontroller will switch over to the rechargeable battery. When the Pro Trinket or ItsyBitsy USB port is powered, the battery is recharged automatically. This LiPoly backpack makes it really easy to do! Instead of wiring 2 or 3 boards together to make a charging system, this little PCB sits on top of the PCB and allows a LiPoly/LiIon battery to plug in. If you have an ItsyBitsy or Pro Trinket you probably know it's the perfect little size for a portable project.

Adafruit trinket 5v pinout