The Adafruit Pro Trinket LiIon/LiPoly Backpack is a tiny add-on board that sits on top of your Pro Trinket or ItsyBitsy, adding rechargeable LiPo battery support with automatic charging and power switching. When USB is connected, the battery charges automatically. Unplug USB and it seamlessly switches to battery power.

The backpack is ideal for the 3.3V Pro Trinket and ItsyBitsy boards, where the 3.7–4.2V battery voltage is regulated down to 3.3V. It can also work with 5V boards in many cases, though this runs the microcontroller slightly outside its rated voltage. Charging uses a three-stage process: preconditioning, constant-current fast charge, then constant-voltage trickle charge.

Key Features

• Automatic LiPo Charging – Three-stage charging via the Pro Trinket/ItsyBitsy Micro-USB port
• Auto Power Switching – Seamless switchover between USB and battery power
• 100 mA Default Charge Rate – Safe for any battery size; adjustable to 500 mA via solder jumper for batteries 500 mAh and larger
• Status LEDs – Red while charging, green when fully charged
• Optional On/Off Switch – Cut a trace and solder in a switch for battery power control
• Compact Piggyback Design – Sits directly on top of the Pro Trinket or ItsyBitsy
• Extra-Long Header – Allows breadboard use even with the backpack installed; trim for a slim package

Compatibility

• Adafruit Pro Trinket 3V (recommended)
• Adafruit Pro Trinket 5V
• Adafruit ItsyBitsy boards
• Adafruit LiPo/Li-Ion 3.7V/4.2V batteries only

Ideal For

• Portable and wearable electronics projects
• Battery-powered sensor stations
• Untethered demonstrations and exhibits
• Any project that needs rechargeable battery support in a compact form factor

Package Contents

• 1× Adafruit Pro Trinket LiIon/LiPoly Backpack (assembled and tested)