Solar USB Charger 2.0

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Everyone has USB gadgets.  It's pretty much a fact of life.  Another fact of life is that these USB gadgets also continually run out of power when you most need them.  No need to fear, solar power is here!  Ditch those crazy wall adaptors, throw out the laptop, and start making your own solar charger!

One of the most popular projects for new Makers is creating their very own Solar USB Charger.  While there are many right ways to do this, there are also many highly inefficient ways.  In 2011 I posted deigns on how to put a simple USB charger in an Altoids tin.  While this proved to be a very useful and fun project that design hasn't held up well over time.  With each new generation of cell phone or MP3 Player batteries get bigger and my original design proves to be less useful.

This guide will show you step by step instructions on how to make your own Solar USB Charger as well as files on how to make a nice looking laser cut wooden box.  This charger will charge most small USB devices such as cell phones, mp3 players, iPods, and iPhones.  These direction are designed to use parts from my Solar USB Charger 2.0 Kit though you can also find many of these parts elsewhere online.  You can also choose to ignore the laser cut wooden case aspect and use a different enclosure, though I'd recommend not using Altoids tin anymore.

This project was designed for beginner Makers and students.  It requires a base knowledge of soldering.  While you can charge small gadgets, this project is not appropriate for camping or to be relied on for extreme emergencies.

Difficulty: Easy
Cost: Low
Time: 30 - 60 minutes
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Charly_ZA1 month ago

Hi, if I used a 12v lead acid battery would it be necessary to use a charge controller? How many AHR would be sufficient?


JoshuaZimmerman (author)  Charly_ZA1 month ago

You'd want to build a much much bigger setup if you were using a 12V Lead Acid. You'd want a big old 12V charge controller and a big 12V solar cell (18V actually).

nbaldan2 months ago

Would i do any changes if i do it for charging an Iphone 5?

WW11372 months ago

How long should it take to charge? I left it in the window for about a week and it charged my phone (galaxy s3) for maybe 5 minutes before cutting out . While it isn't super sunny out, I expected a little more. Is that normal?

Archimidious4 months ago
that's understandable, but in my case I need something lightweight and easy to pack around so its perfect, but to each his own.
JoshuaZimmerman (author)  Archimidious3 months ago

They're just limited in size and metal. A small plastic container would work far better and be far easier to waterproof.

dzulfaqar3 months ago
if i change the battery with battery size D 1.5v and 6000mAH. solar charge still works?
JoshuaZimmerman (author)  dzulfaqar3 months ago
You need to have rechargeable D batteries, regular ones won't recharge. If you have rechargeable ones it would work just the same, only it would take a much longer time to charge up as their capacity is greater than AAs.
Archimidious4 months ago
As I am in the army and need to keep in contact with people this is absolutely necessary for me I switched out the small solar panel for a 5w one and I fit everything into an altoids tin and it fits very nicely, as long as you layer the bottom of the tin with electrical tape you won't have any problems with shorts.
JoshuaZimmerman (author)  Archimidious4 months ago
True, I do love Altoids tins. They're just… not my medium of choice any more.
Archimidious4 months ago
I made this and I absolutely love it the efficiency rate I have calculated at ~90% +/- about 3% for error on my part
JoshuaZimmerman (author)  Archimidious4 months ago
Wow, nicely done!
highestshelf4 months ago
I only have a unused high school knowledge of circuitry, but would it be possible to make a solar charger that could be worn as a bracelet, similar to the wide copper ones popular in the 70's? I see charging bracelets, but they seem to be just battery packs that need to be separately charged.
JoshuaZimmerman (author)  highestshelf4 months ago
Sadly no. The problem is the amount of space the solar cell needs. Yes, you can find some "chargers" with super small solar cells. The issue is that they'd take weeks and weeks of full sun exposure to do any good. Putting one on your wrist would leave it in the dark most of the time.

Now making a backpack or jacket using super expensive flex solar cells, we can do that.
dupes8884 months ago
yeah why havent you
JoshuaZimmerman (author)  dupes8884 months ago
Why haven't you...... what?
astral_mage5 months ago
why havent u though of selling flexible solar panels by now on yr website. way easier to work with. an almost unbreakable as well.
JoshuaZimmerman (author)  astral_mage5 months ago
More expensive, lower output, lower demand from hobbyists. I've tested out several types, but they're not worth it for what I'm doing or the projects I'm making.

I could, but you'd be paying three times as much for the same output solar cell (that is also almost twice the physical size as well).
ferjanyen5 months ago
Hi and a very good project. sell it without box, it will do us a favour as we will have just you to obtain all the bits. Let us decide what type of box we like to use. Make it easy, just put the bits un buble wrap envelope and sed it, no fuss. I'l be the first one to buy one kit from you. thanks. Ferd.
JoshuaZimmerman (author)  ferjanyen5 months ago
All the parts (and more) are available on my site, you can grab whatever you'd like to make this project. Mix and match.

I made the wooden box because I've spent way too much time trouble shooting shorted out projects due to Altoids tins. Insane amounts of hours and replacement parts.
czhanacek5 months ago
Ah okay awesome. Also, is it possible to just use an LED as the diode? Of course, it'll use a bit more power, but that's all I've got lying around right now.
JoshuaZimmerman (author)  czhanacek5 months ago
That wouldn't be a good idea. There would be too great of a voltage drop. A simple 1N914 diode can be found nearly anywhere and are insanely cheap. Go that route.
The trouble with 1N914 (or 1N4148 or 1N4001) is it uses up almost a volt when you pass charging current through it. I'd splurge on a shottky type diode here. You lose less than half a volt. Shottkys leak more than Si P-N diodes like '914 but we don't care about that here. 1N5819 seems to be the "jelly bean" part. Anchor has them for 15 cents in hundreds, Mouser 40 cents each.

An LED would be terrible. You lose two or three volts across it because it's turning it into light.
cls42 cls425 months ago
BTW, when I bought generic Chinese NiMH cells on Ebay they came with a data sheet that said never discharge them to below about a volt. But they want you to charge and discharge the cell fully before using it. I soldered a 1N4148 and a 0.4 ohm resistor in series to a battery holder. Drains them down to 0.95 volts every time. The diode gets rather warm, the resistor doesn't.
Steamcrunk5 months ago
What's the total cost of all the components? (including cost to laser cut box). Great Instructables!
JoshuaZimmerman (author)  Steamcrunk5 months ago
Depends on the parts you use. $30-$40. I sell a kit for $35, and a good chunk of that is the laser cutter time/ materials. If you can find some scrap materials to use, such as the solar cell or batteries, then the price drops quite a bit.
why not just sell kit sans the case / laser cut materials?
JoshuaZimmerman (author)  dcms45 months ago
You can find all of the individual parts on my website, put your own together.
echoalex5 months ago
Totally awesome project ! I need to find access to a laser cutter really soon !
JoshuaZimmerman (author)  echoalex5 months ago
I joined my local Maker Space just to use the laser cutter. They're such a handy tool for making custom parts. If you were to get a decent 3D Printer, Laser Cutter, and mini CNC machine in a shop there is no end to what you could make. (I would make so many weird custom circuit boards with a little CNC machine it wouldn't even be funny.)
czhanacek5 months ago
Is there a certain type of rechargeable battery you recommend? Will any of them work with this setup? Great tutorial, can't wait to try it!
JoshuaZimmerman (author)  czhanacek5 months ago
Any rechargeable AA battery will do. Best part is, if they ever wear out, just swap them out for new ones. The better brand name batteries do have a quality difference over no name batteries. It depends on your budget which you want to go for. You can grab super cheap ones off eBay, but they're noticeably different in output.
Mindmapper15 months ago
lovely idea but why so ugly? it should be a beautiful design, too many laser 'ibles are so over designed. Less is more in my opinion.
JoshuaZimmerman (author)  Mindmapper15 months ago
I actually designed them to be rather pretty. You can easily paint the box or stain it. The other option is a plastic tub... which looks alright or trying to cram it into an Altoids tin... which is conductive and a super tight fit. A laser cut case just seems like a decent solution.
lilly75 months ago
Woah! I got to try that

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