Solar Altoids iPhone/ iPod Charger

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Step 1: Solar Altoids iPhone/ iPod Charger

I love my iPhone 4 to death.  I really do.  Even if it sucks juice faster than a 1st grader at snack time and I often find myself on low power with a long train ride ahead of me.

I originally made my Altoids USB Charger to use with my iPhone, only to find that Apple being Apple doesn't let it's products play nice with generic USB chargers.  I then set out on a long journey to find a cheap charger that would work with an iPhone 4.  After sacrificing many a cheap Chinese charger to my garbage can I eventually found a great little circuit with the added bonus of having a retractable cable.

It's a cheap and easy project to put together and a great gift to give.

*** Update:  I've since retired this kit.  It's not held up over time very well.  I've done an updated version called
Solar USB Kit 2.0 and a more rugged version called Lithium Heavy Duty 2.0.  If you're looking for something pre made, especially for camping or emergencies, you should try out one of our Folding USB Solar Cells.  They're inexpensive and much much more powerful than what you'll find here.

Time: 30-60 minutes
Cost: Under $20
Difficulty: Easy

Step 2: What You Need

Charging Circuit
2x AA Battery Holder
2x Rechargeable Batteries
1N914 Blocking Diode
Solar Cell greater than 4V
Stranded Wire

Altoids Tin

Soldering Iron
Hot Glue Gun
Wire Strippers
Protective Goggles

If you're interested in this project I have kits available on my website,, that have everything you need to make the charger.  If you're not one for making things I  sell premade chargers as well. 

More than 12% of all profits go to dog and kitty toys.  You wouldn't make a kitty cry, would you?

Step 3: The Charging Circuit

For this project I've stolen a charging circuit from an Emergency iPod charger I got off ebay.  You can find these all over the place.  The key is to find one that will work with an iPhone.

Apple decided to have it's newer iDevices not follow USB standards.  When an iDevice is plugged in it checks the data tabs on the USB to see what it's plugged into.  Depending on what it finds it sucks more or less power, which makes sense but is annoying because NOTHING ELSE DOES THIS.  Thus no charger out there has any power flowing to the data tabs.

So the key is to find one that works for your newer iPod or iPhone.  If you have an older iPod or iPhone when you don't really need to worry all that much.

(For a USB Version of this, check out this instructable.)

If you want to make your own circuit you can always use a Mintyboost kit.

Step 4: Batteries

What I really find annoying is that on all the commercial solar chargers I see their internal battery is only 1000 mAh. That isn't a lot. A rechargeable AA battery has between 2000 - 3000 mAh of current in it. We can do better.

We need to use rechargeable batteries for this project. I prefer NiMh AAs over everything else because they're easy to find, cheap, and reliable. You probably even have a few at home. Since we're using two AAs in this project our charger will have 2000 - 3000 mAh of current. You could even have two sets of AAs in parallel and boost that capacity to 4000 - 6000 mAh.

An added bonus from rechargeable AAs is that you can take them out of the Solar Charger, charge them up or replace them, and be on your way. 

Find some cheap ones and use them.

Step 5: Choose Your Solar Cell

If we use two rechargeable AAs that put out a total of 2.4Vs we're going to need a solar panel that is at least 3 - 4Vs just to meet basic levels of charging. The higher the voltage of our solar cell (or cells) the less light we need to charge up our batteries.

Now we're also trying to fit this into an Altoids Tin, so we're limited in space. I have found some great 4V solar cells that perfectly fit into Altoids Tins. They're the same ones I use with my Solar AA Atoids Charger.

Sure, a bigger and better solar cell would give us added power, but it wouldn't fit into our tin. (Something that has annoyed me with nearly every Altoids Solar Guide out there.)

You could also use a combination of several smaller cells to get your four volts. For example, 2V cells are very cheap and small on ebay. You could easily connect two of those in a series to get your 4Vs.

Just remember that when charging NiMh batteries we don't want to throw more than 10% of their capacity at them at any one time. For instance if your battery has a capacity of 2000 ma we can only use a solar cell that puts out 200 ma or less of current. This isn't usually a problem unless you're using a massive solar cell or a big combination of cells. None the less, keep this in mind.

Now if you're not using an Altoids tin you can always go crazy with a big solar cell.  As you can see in the picture I have a lot of cells to choose from.  Variety is the solar cell of life.

Every cell pictured above is available on my website,  Great for all sorts of fun projects.

Step 6: Strip Your Wires

First strip your wires. 

Cut off 1/3rd of the wire from the battery holder and then strip some coating off the end.

Now cut a couple lengths of wire about 8 inches long.  Strip the coating off each end.


Step 7: Solder The Solar Cell

First wrap one of your 8inch wires around your diode.  Look at the diode.  One side has a black bar.  This is the negative end.  Wrap your wire around that end.

Then just solder the wire to the negative end of the diode.

The positive end of the diode should then be soldered to the solar panel's positive tab.

Use your second wire on the negative point on the solar cell.

Step 8: Twist Up

Take the red wire (positive) from the battery pack and twist it together with the positive wire from the solar cell.

Take the black wire (negative) from the battery pack and twist it together with the negative wire from the solar cell.

Don't solder.  Seriously don't.  Go get a cup of tea and relax.

Crazy fools.

Step 9: Solder The Circuit

This is the most difficult part of the project.

Look at the circuit.  You should be able to find a Positive (+) and a Negative (-) point on it.  Just look for the battery tabs.

Now you don't have to remove the battery tabs, you can leave them where they are.  Usually they are very easy to break off and it does save you some space.

Now just solder the positive cluster of wires to the positive point on the board, and the negative cluster of wires to the negative point on the board.

Now the big problem I see people having with projects like this is that they use too much solder.  Lets refresh how we solder so we don't cause any shorts.

Touch your soldering iron to the wires and wait five seconds.  Then touch the solder to the wires.  DO NOT directly touch the soldering iron with the solder.  The goal is to heat up the wires.  When they're hot enough the solder will flow nicely.

You don't need a lot of solder to get the wires to stick.  Just a dab. 

Step 10: Tape Things Up

Now that we're all done you can tape things up.

Use some electrical tape and tape up your solar cell.  Cut off any extra diode or wire.

If you're using a tin it wouldn't be a bad idea to tap up the area where you're going to put the circuit.  Just on the off chance that you might get a short because of the tin surface. 

The top right corner is a good spot. To put the circuit.

Step 11: Glue It Down

BUT WAIT!  Before we glue down why not test out the circuit to see if it's working?  You can even just throw in some regular AA batteries to see if everything is charging up well.

Throw some hot glue down on the far left side of the tin where your battery holder will be.  Then, put the battery holder down. 

TAKE BATTERIES OUT BEFORE YOU DO THIS.  Otherwise they'll probably get glued down as well.

Now throw some glue down where you want your circuit to be.  Place the circuit on top of it and hold it down.  You want it as far back as you can in the tin.

Once the glue is dry we're going to go back for Round 2.  We want to make sure the retractable cable is nice and secure.  I usually scrunch the cable into the back corner and then throw down a whole lot of glue over the top of it.  This was I don't have to worry about pulling the cable off.

Once that's dry you're totally done.

Step 12: Before Using

Before you start using the charger you should do a couple of things.

1st, charger up the batteries.  You can do this either through large amounts of sun or by using a wall charger.

I've found that if the batteries get low on power the iPhone will throw out an error message saying "Not compatible for charging with iPhone" and then refuse to charge.  Just charge up the batteries again and life will be good.

2nd, figure out how everything fits in there.  The retractable cable will lay flat on the bottom if you've got everything spaced out correctly.  The solar cell will also fit inside the tin. 

If you're having issues with the solar cell try turning it around clockwise.  This bunches up the wires and allows for it to fit in a bit better. 

It can sometimes be a tight fit, but believe me, everything fits.

3rd, if you're having issues with your iPhone or iPod and charging try using some regular batteries.  If they work then that means that your rechargeable batteries just need a recharge.  Also keep this in mind.  In a pinch you can always throw in regular batteries to charge up your phone.  Like if zombies are attacking at night.

    Step 13: Enjoy!

    And you're done.  Easy as pie you bought from the grocery store because you don't know how to make pie.

    The only downside to this project is that you can't get an iPhone to charge directly from the sun.  Our little solar cell just doesn't put out enough current to charge up the iPhone.  Sadness.

    If you're interested in the project I do have kits on my website available, as well as all the parts you might need for making a similar project.

    Its amazing what you can do with a couple of solar cells and batteries.  Plus things like this make great gifts.

    *** Update:  I've since retired this kit.  It's not held up over time very well.  I've done an updated version called Solar USB Kit 2.0 and a more rugged version called Lithium Heavy Duty 2.0.  If you're looking for something pre made, especially for camping or emergencies, you should try out one of our Folding USB Solar Cells.  They're inexpensive and much much more powerful than what you'll find here.

    License: Attribution-NonCommercial-ShareAlike.

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