How to make a solar iPod/iPhone charger -aka MightyMintyBoost

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I wanted a charger for my iPodTouch and the MintyBoost was definitely my first choice. I wanted to take it a bit further and make it not only rechargeable but also solar powered. The other issue is that the iPhone and iPodTouch have large batteries in them and will deplete the two AA batteries in the MintyBoost rather quickly so I wanted to increase the battery power as well. What I really wanted was a MightyMintyBoost!

Apple has sold over 30 million iPodTouch/iPhone units- imagine charging all of them via solar power.... If every iPhone/iPodTouch sold was fully charged every day (averaging the battery capacity) via solar power instead of fossil fuel power we would save approximately 50.644gWh of energy, roughly equivalent to 75,965,625 lbs. of CO2 in the atmosphere per year. Granted that's a best case scenario (assuming you can get enough sunlight per day and approximately 1.5 lbs. CO2 produced per kWh used.) Of course, that doesn't even figure in all the other iPods, cell phones, PDAs, microcontrollers (I use it to power my Arduino projects) and other USB devices that can be powered by this charger- one little solar cell charger may not seem like it can make a difference but add all those millions of devices together and that's a lot of energy!

There are some really nice features about this charger:

It's solar powered!
It's small.
Large battery capacity- 3.7v @2000mAh
On board charger charges via solar, USB or wall wart. Accepts input power from 3.7v to 7v.
Remove the solar cell after charging and you have a nice compact USB power supply.
Unplug the solar cell and use the Velcro to secure the MightyMintyBoost inside a backpack or messenger bag- now plug in a larger solar cell attached to your bag for even faster charging. Using a slightly larger solar cell (6v/250mAh) you can generate enough power to fully charge an iPhone in about 5.5 hours and an iPod Touch in 4 hours.

Building this is really easy and straightforward- it only took me around an hour so follow along and build one for yourself!

Safety note and general disclaimer: Be careful cutting the Altoids tin as it can have some really sharp edges- file them smooth if necessary. Assemble this at your own risk- while it is really easy to build, if you mess something up there is the potential to damage the electronic device you are trying to charge. Be careful in your assembly and soldering work and follow good safety practices. Only use a type of battery charger specifically designed for the type of battery you are using. Please read through the entire Instructable before asking questions- if there are are any questions just ask and I'll help out as best as I can!
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Honus (author)  ajissupercool1 year ago
Probably not- they recommend a 6V solar panel.
Thanks Honus!
Honus (author)  ajissupercool1 year ago
how do you know which polarity the black and blue wires of the JST connector is?
Honus (author)  ajissupercool1 year ago
Match it up to the female plug and use a meter to test which is ground.
Thanks! They're possibly one of the best made containers of any sort.
Thanks! They're possibly one of the best made containers of any sort.
Kelly021 year ago
Amazing!!! Great job!!
Gavin7371 year ago
Great guide, but one question. Do you think that this panel would be good enough to use with the new adafruit lipoly battery for this project?
Honus (author)  Gavin7371 year ago
It's well within the parameters of the charger so I'd say sure.
fffair1 year ago
How do you think this design, if put together with adafruit's Large 6V 3.4W Solar panel - 3.4 Watt, USB / DC / Solar Lithium Ion/Polymer charger - v2, Lithium Ion Polymer Battery - 3.7v 2600mAh, and its MintyBoost Kit - v3.0, stacks up with JOOS's Orange2?[]
It seems like the double battery capacity of the Orange could be a plus, but I'm not sure if the solar side of it is as good. I'd prefer to make the minty boost, but I'm not sure if its totally cost effective. Any thoughts?
Honus (author)  fffair1 year ago
It's a tough comparison. :) The Orange is a really nice finished product and looks to be really rugged. The cost is less for the Adafruit setup but it could be close once you add a nice enclosure for the Adafruit parts. I'm guessing the overall performance will be similar in terms of charge time relative to capacity.
Schmidty161 year ago

can u also find me one of these USB / DC / Solar Lithium Ion/Polymer charger - v1.0
Honus (author)  Schmidty161 year ago
That charger is no longer sold. If you read through the instructable you can see some of the alternatives I have listed.
Schmidty161 year ago
can u also help me find a battery like this on the RadioShack website
Same with the jumper Wires
Schmidty161 year ago
would this work for the solar:
Honus (author)  Schmidty161 year ago
Yep, that will work.
Schmidty161 year ago
ok thanks you were fast on that question
Schmidty161 year ago
if I were to use a pelican case what type of solar cell should I use and what are all the parts I need to make this .Can u give me a list of the stuff I need?
Honus (author)  Schmidty161 year ago
You can use whatever solar cell you want as long as it outputs enough voltage/current. There is a complete list of everything you need on the Tools and Materials page.
CODawesome1 year ago
äbädrän1 year ago
can this solar charge charge my samsung s3???
please reply to me
my s3 battery is 3.8v 2100 mAh
if i buy a 4v and 2100 mAh battery would the phone charge?
can this solar charger charge nokia phones
Honus (author)  äbädrän1 year ago
Have a look at the FAQ page- you'll find a link to a compatibility page.
very nicely explained i will try it out i found this site after starting to build this DIY version.

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very nicely explained i will try it out i found this site after starting to build this DIY version.

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jonsleepy2 years ago
Awesome idea! And I noticed Adafruit's new optimized solar charger, too! However, I still feel attached to AA batteries - I have several devices that use them. I would rather avoid using the lithium polymer battery packs - to me, they feel like added weight and a "middleman", even though I realize they can store more charge per gram of weight. Is there a way to get power from the panel into a circuit and into the AA batteries in the original Mintyboost? Therefore I could swap AA batteries into and out of the Mintyboost, and recharge as needed, without the use of the Lithium battery?
Honus (author)  jonsleepy2 years ago
Yep, you could do that. Basically you would just substitute the LiPo cell and charging circuit. Just use two AA rechargeable batteries with a compatible charging circuit instead- you need to make sure you get the right type of charging circuit for whatever battery chemistry you AA batteries are.
jonsleepy Honus2 years ago
Thanks for the reply! So then there's 2 circuits.. one to convert the 1.2 (or 1.5) volts x 2 AA batteries into 5V for USB out.. and the second to convert whatever the solar panel can put out into whatever the batteries need to charge. Is that it? Say I want to charge 2-4 AA NiMH batteries. I'm not sure I know how to determine what I'd need, but I'll look around.

Actually, I found this:

but I'd want to have the option of using whatever solar panel I want, and adding more batteries. Just not quite sure how to make that modification or if this is the best way to go. Aah well, I'll get there!

Honus (author)  jonsleepy2 years ago
That's it- the MintyBoost circuit takes your battery voltage and converts it to a stable 5V output. The charging circuit takes the output from the solar panel and uses that to charge your battery that powers the MintyBoost.
lawidhalm2 years ago
I love this project, and thought I'm years late I had a few questions. You say it can take 3-7 volts input...what about current requirements? I ask because I'm using those garden solar cells about 4 volts each, but have a rather low current output. Does this just mean it will trickle charge all day?

Second, does this work on iphone 4s? I don't see why it wouldn't but definitely worth asking

Third, do you happen to know of a way (or an entirely different project) to modify a wall charger to then be solar powered? I feel like there should be a way to gut the ones you get at the store that plug in, use everything after they convert it from AC to DC because its designed explicitly for charging. Then all you'd have to do is connect your battery from that point on and it should work right? Just thought I'd ask - thanks!
Honus (author)  lawidhalm2 years ago
The charging circuit can only pull so much current- it will max out a 500mA. The less current your solar cells provide the longer it will take to charge.

The current MintyBoost circuit will work with an iPhone 4s.

I don't know anything about modifying a AC charger to solar power. It's probably much more trouble than it's worth. To see an IPhone wall charger teardown have a look here-
lluvaitech2 years ago
if i want to make this experiment, i think i should buy another batery.
markee23 years ago
Am building one but got some charging problem with iPhone.

Adding the circuit below can solve the problem.. maybe, anyone got some idea?  circuit copied from:

ChargingNotSupportediPhone.jpgiPhone charger schematic.jpg
Can I still charge other smartphones, like my android device (Which just uses 5V and GND)? I don't want to fry my phone because I put resistors to the data lines...
Honus (author)  kentsfield2 years ago
The version 3.0 Mintyboost works with most all Apple products (except iPad) and works with several Android phones. There is a compatibility list here-
Thanks Honus, but I don't use the Minty Boost. I made my own little charging circuit using a 9V battery and a 7805 linear voltage regulator. I have an iPod Touch and a Android smartphone and want to charge both of them, but as I said, I am unsure if I can still charge "normal" phones with the "iMode".
Honus (author)  kentsfield2 years ago
It doesn't matter- the output is the same after the regulator. All that matters is the interaction on the USB data lines so if it is listed on the compatibility page then it should probably work- just use the same resistor values as the v3 Mintyboost.
I think you get that when the input power is too low...I've got that on a car charger.
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