Instructables

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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Love this setup,

I plan on building a 12V system for other power hungry applications, but instead of a flimsy altoids can, i decided to beef it up a bit with a pelican project box. If anyone has any suggestions about how to cover ports a little better, that would be great.

Check it out!

Love the instructable! Great work.
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Love the case. I wonder if you could use sugru around the ports to make secure fittings. http://sugru.com

How much did you pay for yours.
Honus (author)  Landcruiser874 years ago
Looks awesome. Pelican cases are great- I have a large one that's over 15yrs old and it's still going strong. Maybe for port covers you could mold some silicone plugs. Try Sugru!
Thanks! They're possibly one of the best made containers of any sort. I've been using them for various things here and there over the past 7 or 8 years. I like the idea of using Sugru for port covers! I was having all sorts of failed trials with grommets, silicon and other failed devices, but sugru might just be the ticket. Thanks Honus!

Honus (author)  Landcruiser874 years ago
No problem- let me know how it works out!

Hey! I built this for my science fair project and I have a problem with it. Whenever I charge up the battery through USB or solar power, a few minutes later, it doesn't charge at all. It's like the battery doesn't work or something. My setup looks exactly like the one in this picture https://learn.adafruit.com/assets/1482 . Also, I don't know if this matters but what does it mean when I charge this with solar power, the power LED light flickers over and over rapidly. While when I use a USB through a wall outlet, it doesn't flicker at all. This project is due in about a week or a week and a half. I'd appreciate any help if possible.

Honus (author)  MeetHarry100.5 days ago
So it begins charging and then stops? It sounds like the flickering LED is showing that you're not getting a consistent output from your solar panel. When it does this is it in direct sunlight?

Sorry, I was thinking of something else but what I typed isn't really my problem. What's happening is if I charge the battery with solar power from the sun, the battery only seems to hold onto that energy for a few hours and then it all just disappears . I don't use it while its charging nor after I charged it. Also, when the light flickers, I am using it under direct sunlight.

Honus (author)  MeetHarry100.4 days ago

What solar panel are you using and have you checked its output? If
you're using the Adafruit solar charger circuit they recommend a solar
panel that puts out at least 6V. As far as the battery charge
dissipating that has me stumped- there has to be some load somewhere
that is draining the battery. Maybe there is a short somewhere? Check
the battery voltage before and after charging and let me know what it
is. The battery voltage shouldn't ever drop below 2.8V and at full
charge it should be around 4.2V.

Hmm, maybe the solar panel is the problem? I bought the same one put at the top of the website. It has 0.45W and it's rated for a 4.5 open voltage. Here is where I got mine from. https://www.sparkfun.com/products/7845

As for the battery, I just tested what I had now since it is dark out, the multimeter showed me 4.17V in the battery.

Honus (author)  MeetHarry100.3 days ago

That could definitely be part of the problem as that panel was what I used for the original charging circuit- Adafruit specifies a higher output panel for their charging circuit.

It appears that your battery has a full charge. I'd check the battery voltage again in a few hours to see if there is a drain on it.

Okay, so I'll try to buy a different panel. I plan on rechecking the battery voltage in the morning once I leave for school and tell you the results asap. Also, since i noticed that the battery has a charge, I went ahead and tried to charge my phone with it, but it didn't work. But for some odd reason when I plug in my USB power meter, ( I bought it from Amazon. Here's the link : http://www.amazon.com/DROK-Dual-USB-Voltmeter-Multimeter-Alignment/dp/B00J3JSEG6/ref=pd_cp_pc_1 ) it showed me 3.9V and 0 amps. Any idea's as to why I can't charge my phone but the USB power meter still shows that there's energy?

Honus (author)  MeetHarry100.3 days ago

What kind of phone do you have?

I have an iPhone 5s that was bought about a year and a half ago.

Honus (author)  MeetHarry100.2 days ago

OK so you have good battery voltage but the Mintyboost circuit output is at 3.9V and the 5s is a supported device according to the Mintyboost specs. I would double check all of your soldered joints on the Mintyboost circuit and make sure all of the parts are installed correctly. If your battery voltage is good you should be seeing a regulated 5V output out of the Mintyboost USB output- it won't charge your phone if the output is less than 5V. I think that's the problem and it would definitely explain why the phone isn't charging.

Wonderful project. Thanks for the clear instructable

SparkySolar1 month ago

Love this Intractable

AidanT2 months ago

Hi- love the idea. How would you modify it to make it into an ipad 4 charger?

Honus (author)  AidanT1 month ago
You would just need to figure the pinout for the thunderbolt connector. It would take it an awfully long time to charge an iPad though since the batteries in those are much larger.
AidanT Honus1 month ago
Would I be able to add a higher wattage solar panel to get more energy quicker, and what would I have to do to do this? Also, would I need to add more batteries to the pack to increase capacity?
Honus (author)  AidanT1 month ago

You can certainly do that. Have a look at the FAQ section- there is a charger listed there than can handle up to 1 Amp. You absolutely can add a larger capacity battery and you don't need to change the circuit at all.

mpmuebles2 months ago

good project. well done!

interesting, and the solar parts looks small and nice.

Mr_Rep3 months ago

i have a 7.2v Ni-Mh rechargable battery would this be effective with a 6v 1Watt solar cell?

Honus (author)  Mr_Rep3 months ago
No it wouldn't work. The charging circuit is designed to work only with single cell LiPo batteries.
Mr_Rep Honus3 months ago
Hhmm...'ok thanks.
mmcgo made it!6 months ago

I made one out of an old Shrek DVD case because I have a bad sense of humor. I also made an adjustable stand with Velcro that allows me to adjust the angle of the solar panel. Works very well, but do be conscious of the casing you pick out. Because this case is black, it can heat up rather quickly, which reduces performance and risks damaging the circuitry and battery inside. I always make sure to hide the case from the sun, which can be a bit inconvenient since the panel is on a short leash.

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sniffrumble6 months ago

Looks awesome. Pelican cases are great- I have a large one that's over 15yrs old and it's still going strong. Maybe for port covers you could mold some silicone plugs. Try Sugru!

No- LiPo cells are very particular regarding charging rates so you must use a proper charging circuit.

No- LiPo cells are very particular regarding charging rates so you must use a proper charging circuit.

R-A6 months ago

Is it possible to charge the Lipo battery directly off the solar panel, instead of using a charging circiut - which adds cost to the project?

Honus (author)  R-A6 months ago
No- LiPo cells are very particular regarding charging rates so you must use a proper charging circuit.
sheepbars8 months ago

Thanks! They're possibly one of the best made containers of any sort. I've been using them for various things here and there over the past 7 or 8 years. I like the idea of using Sugru for port covers! I was having all sorts of failed trials with grommets, silicon and other failed devices, but sugru might just be the ticket. Thanks Honus!

MonteBT8 months ago

Can someone please help me. So I am using the USB/DC/Solar Lithium Ion/ Polymer Charger by Adafruit(http://www.adafruit.com/products/390?gclid=CP6djK3izL0CFYqIfgodLIoAyg) and the problem that I am having is that the yellow charging light on the PCB is lit even if the solar panel is not exposed to sunlight. I can't seem to identify what part of the circuit is wrong? Does this mean that some of my connections are not right? Or maybe I need to get a new Polymer charger? Any help is appreciated. Thanks in advance.

Honus (author)  MonteBT8 months ago
MonteBT Honus8 months ago
Thank you.

I plan on building a 12V system for other power hungry applications, but instead of a flimsy altoids can, i decided to beef it up a bit with a pelican project box. If anyone has any suggestions about how to cover ports a little better, that would be great.

Sawgywaffles9 months ago

Is there a circuit diagram

Honus (author)  Sawgywaffles9 months ago
Have a look at the FAQ section.
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