Make your projects to go green this summer with our specialized USB/Solar Lithium Ion Polymer Battery charger! This charger is a very unique design, perfect for outdoor projects, or DIY iPod chargers. We've spent over a year testing and tinkering with this charger to come up with a plug and play solution to charging batteries with the sun and we're really pleased with what we ended up with.

Please note: we now have a newer, easier, and cheaper design for solar charging - check out the bq24074-based Adafruit Universal USB / DC / Solar Lithium Ion/Polymer charger! It has more input protection and wider voltage range, no need for a large capacitor, USB C, and more. We'll continue stocking this older design for folks who need it. For new Solar charging projects, please use the bq24074.

Easy to use! Pick up any of our many 3.7V/4.2V LiIon batteries, and a 6V solar panel. Plug the battery into the BATT port using a 2-pin JST cable and the solar panel into the DC jack using a 2.1mm adapter cable Put the solar panel outside (and keep the battery out of the sun, it needs to be kept cool!) to start charging. You can power another project like a Mintyboost at the same time by connecting to the LOAD output port
Our carefully designed charger is designed specifically for solar charging, and will automatically draw the most current possible from the panel in any light condition! Even thought it isn't a 'true' MPPT (max power point tracker), it has near-identical performance without the additional cost of a buck-converter. Our detailed tutorial on how to use this charger includes a design document explaining how it all works.
For use with Adafruit Lipoly/LiIon batteries only! Other batteries may have different voltage, chemistry, polarity or pinout.

This product is only designed for use with solar panels sold at the Adafruit store. We cannot guarantee this will work with solar panels purchased elsewhere. Please purchase this kit and panels from Adafruit to ensure optimized functionality! Using larger panels, either higher voltage or current output, could also damage the charger. A 2.1mm adapter cable is also required to adapt a solar panel to the DC power jack.

Comes with an assembled charger board, a 2-pin JST cable that will fit into either the BATT or LOAD ports, and a large stabilization capacitor that must be installed in your finished project. Does not come with a Lipoly battery or solar panel but we do have tons available in the shop that work quite well. We have updated the design to be a little more compact, have nicer mounting holes, and a 2.1mm DC jack

3.7V/4.2V Lithium Ion or Lithium Polymer battery charger
Charge with 5-6V DC, USB or 6V solar panel!
Too dark out? Use a USB Type C cable or a 5V DC adapter
Automatic charging current tracking for high efficiency use of any wattage solar panel
Use any 6V solar panel
Three color indicator LEDs - Power good, Charging and Done
Low Battery Indicator (fixed at 3.1V) with LED output
Set for 500mA max charge rate, can be adjusted from 50mA up to 1A by soldering in a resistor
Will always draw the most current possible from a solar cell - up to the max charge rate!
Smart load sharing automatically uses the input power when available, to keep battery from constantly charging/discharging
Temperature monitoring of battery by soldering in a 10K NTC thermistor (not included) - suggested for outdoor projects where the battery may get hot (50°C) or cold (0°C).

Technical Details:

Revision History:

As of April 18, 2023 – we've updated this PCB with Adafruit Pinguin to make a lovely and legible silkscreen. We've also updated this to USB Type C instead of Mini B

Board Dimensions: 41mm x 33mm x 2mm (1.6" x 1.3" x 0.08")
Thickness with 2.1mm SMT Barrel Jack: 12.6mm / 0.5"

Documentation: