Solar iPhone Charger

April 7, 2011
phone chargerParts List:1. MintyBoost USB Charger Kit v2.0
2. 6V 200mA solar cell
3. 3.7V – 7.0V LiPoly charger
4. 3.7V 2000mAh polymer lithium ion batteries 

I followed the directions from Make available here. Basically you make a Minty Boost 2.0 kit from Adafruit and add a solar panel (also from Adafruit), battery and battery charging module from Sparkfun.

Project Status

5/1/10 Parts ordered
5/7/10 Some parts arrive – start assembly.
5/11/10 It works! Finished assembly except for box.
5/15 Doesn’t work exactly. I can charge an old iPod, but not the iPhone 3Gs. May have to do with voltage levels on usb pins 2&3. More research is needed.
This seems like a good place to start researching.
6/16/10 Put project in a mint tin. Seems to work ok, but sometimes finicky about charging iPhone.
8/4/10 Works great! Previous problems probably due to not charging battery up enough. I have been using it for over a month now. The battery can be charged up to 4.16 v.
This setup works best if the solar panel is actually outside, not behind a window or screen.
8/8/10 Adafruit now sells all the necessary parts for this project and has a new version of Minty Boost out.

4/6/11 Still using it – works great.  Usually let charge for a day or two before using depending on weather.

Click through for more pictures.



  1. Hello there, for the mintyboost, what value resistors did you use for D+ D- to get the iphone 4 to work properly? I have purchased two kits and cannot get them to work with my iphone 4…


  2. I have 2 100k resistors on my Minty Boost. I have an iPhone 3Gs

  3. Hi Todd, is that 100k for R1 and R3?


  4. That sounds right, but I can’t check it right now. The Minty Boost vs 2 only has 2 resistors. It is a little finicky and I do need to let the battery charge a day or 2 in full sun. Good luck and let me know how it goes.

  5. Hi Todd, I finally got it working… I increased the cap to 880uF and it works fine now.


  6. Awesome George.

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