I've been reading a bunch of blogs this fine Earth Day morning and have noticed that most of them are posting little write ups about green solar powered USB gadget chargers. They're all quite nice, but also quite expensive. I don't think I've seen any for less than $60, and I've not seen one that really suits my style.

Instructables has quite a few guides on how to make Solar USB Chargers, including the very well done guide on how to combine a Lady Ada Minty Boost circuit with a solar + lithium ion battery. Great, but a bit expensive to make and not a very simple project for the weekend DIY person.

Well luckily for us I know how to make one for under $20 that is better in nearly every way and also completely fits into an Altoids Tin. Covert style.

*** 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.

Step 1: What You Need

USB Charging Circuit
Solar Panel 4V or greater
AA Battery Holder
AA Rechargeable Batteries
1N914 Diode
Altoid Tin (or whatever)

Soldering Iron
Tin Snips
Melt Glue Gun and Glue

Cost is less than $30. I can make one for under $10 when I buy parts in bulk. Ihave a kit available at my website BrownDogGadgets.com which has everything you need to make this project. Also, if you're lazy, I do sell made versions in a variety of tin styles.

<p>Hey so I've made my first solar usb charger, but I'm having strange issues. I'm starting to wonder whether these usb circuit boards are crap, because, when I check for continuity on the board, touches the leads of my multimeter to the positive and negative all I get is an OL and silence (yes I'm in the right mode on the MM). Whenever I try to charge my phone, my battery drains if I'm charging off the battery. Or, if I'm trying to only use the solar panel, I get this weird pulsing of a few volts. It's really weird. I'm only a novice, but I'm very interested in troubleshooting this problem. I think I'd learn a lot if anyone had ideas on what was going on. I'm about to stick some non-rechargeable batteries in and get some reading so I at least have a control here. Anyway, please some advice or help would be greatly appreciated. I want to solve this puzzle!!! Thanks. </p>
<p>so the problem might be how many batteries you're using you need 4aa batteries to give you enough volts to fully charge your phone (1 aa battery gives 1.5 volts and you need 5 volts to charge your phone) if you have say 2 then your phone will try to charge the batteries or if the phone started out dead or close to it it would just not get much charge at all because they would equal out in volts. Or it might be that your panel does not put out five volts so one of the same problems will happen</p>
<p>Thanks CalebS68! I made some progress and realized that the solar panels are really sensitive and output 6v in direct direct, emphasis on the direct, sunlight, and the usb circuit converts down to 5v. But you're right, I only have 2aa batteries in my charger, which would explain why it doesn't output the right amount when the solar panel isn't used. Strange that the tutorial mentioned that the ma are the only thing that matters in charging via batteries. I bought 2700 mAh batteries... I will look into this further! Thank you for the heads up!! Much appreciated!</p>
<p>how are you creatong more energy through the controller</p>
Do you have to use that specific diode? or could you use a different diode?<br>
Im looking to create this project but i was wondering if i could wire in the solar panel to a portable charging bank?
<p>Would you be able to adapt this concept for a bigger battery to get a longer charge? Also for the battery listed would you be able to over charge the batteries or can you just let this sit out all day?</p>
If i don't want batteries I need my system, just a direct charge. Would it harm anything to leave out the battery pack and wire this directly to the USB charge controller?
<p>i have IN4007 bmc will it work fine</p>
Is there a way of adding a led power indicator into the the circuit to monitor how full the rechargeables are?
<p>Thats a common question. Unfortunately due to the simplicity of this project adding in a meter would be rather difficult. You're better off doing that if you make a lithium battery version of this kit. Most lithium charge controllers have a built in battery monitor that gives you some indication of charging.</p>
<p>Could this be done using an 18650 battery? I am thinking this way I could set it in a window to charge all day and get a full charge or 2 to my cell phone off it.</p>
use 3 18650s and a 3.7 to 5v boost circut and charger in one in an altoids tin, if you get really good 18650s then you can have 10400 mah in an altoids tin, enough to charge your phone many times
<p>Yup, lithium is better provided you're safe about it.</p>
<p>By 'USB charger' do you mean the cable or a wall adapter?</p>
<p><a href="http://www.browndoggadgets.com/products/usb-charging-circuit" rel="nofollow">http://www.browndoggadgets.com/products/usb-chargi...</a></p><p>It would be more like a wall adapter</p>
<p>Wall adaptors convert AC to DC. You want a DC to DC boosting circuit.</p>
<p>Does this work for apple lightning charger such as those used with the newer iPhones? </p>
<p>That is will.</p>
Could i cannibalise part of a wall charger minus the transformer
<p>No, thats an AC to DC converter. It'll take 120V AC and turn it into 5V DC.</p><p>What we're doing is taking 2.4V or 3.6 V (2 or 3 AAs) DC and turning it into 5V DC.</p>
Also could i use solar cells out of landscape lights and the batteries
<p>You could. But you'd need the USB aspect to charge a phone.</p>
<p>There is, of course, an easier and cheaper way to acquire the materials needed to make this project, including the case itself, depending on whether or not you can locate the item in the attached picture.</p><p>The attached image is an aluminum post light. I purchased a few of them, and payed 10$ for each. However, I found more appealing and higher-quality lights, so I decided to do something with them. You will need two of these for this.</p><p>The top of the post is an aluminum screw-top containing a number of small electronics: a small circuit board controlling the LED light based on whether or not energy is coming from the solar panel, a 3V white bright LED, a 1.5V solar panel, and a 1.2V Ni-CD rechargeable battery. Though it is optional, you may use the LED as an attached flashlight.</p><p>Dissassemble the light, then use a flat-head screwdriver to remove the various parts inside, making sure to leave the plastic, solar panels and battery contacts in both parts remain intact and in place; it will make your work easier, though it is purely optional.</p><p>Remove enough plastic to allow an opening for the USB output, then bend the aluminum shell inward to make an opening. Insert the USB output, solder the proper wires and connections, then hot-glue the two halves together.</p><p>Congratulations! You saved 10$, plus postage and the time spent waiting for the parts to arrive.</p>
<p>Except it's missing the entire USB voltage boosting aspect of the circuit, a USB port, and a decent battery capacity. What you have right there is a circuit that'll put out around 3V of power and has a battery capacity of around 800mA. More or less useless when trying to charge up a phone seeing how a phone, or any USB gadget, needs 5V. So theres that whole aspect.</p>
Oh ur made version is a way too costly.......
<p>Whenever we get the charger to work the batteries start smoking, the battery pack melts, and the charger breaks. My teacher was wondering if we could get your phone number or email to ask further questions. Please get back to me as soon as possible. Thank you!</p>
<p>Nice project...!! Useful one......... But what is the alternative of regular batteries ? </p>
<p>sorry, where have u find the usb charging circuit</p>
<p>The DC-DC charge circuit for this project costs 57c on AliExpress with free shipping.</p><p><a href="http://www.aliexpress.com/item/1Pcs-Mini-DC-DC-USB-0-9V-5V-to-5V-Boost-Step-up-Power-Supply-Module/32383087922.html" rel="nofollow">http://www.aliexpress.com/item/1Pcs-Mini-DC-DC-USB...</a></p>
<p>My website, browndoggadgets.com</p>
<p>I purchased a cell phone battery pack extender and was not impressed so I'm looking into making my own. I first tried connecting one of those cigarette lighter USB converters into a 12V power point adapter connected to a 9V battery but the phone would not constantly charge. If that makes sense. </p><p>But charges perfectly fine off the 6V car battery on my Trabant. The only thing I can think of is the milliamp per hour rating of the 9V battery I was using was too low to support charging.</p>
<p>i love it</p>
the OP mentioned that you can take the circuit out of a phone charger and use it for this project. what I'm wondering, though, is that the project calls for a DC to USB circuit, whereas the wall chargers would be AC to USB circuits, right? if this is correct, do I need to do anything to alter the chip I take out of the charger in any way to fit with the project, or can I use it as is and just insert it into the new circuit?
Nice build. Do you think if you placed a mirror in the lid you could use it to refract more light onto the solar panel? <br><br>Have a great day! :-)
<p>Nah, it would be a super duper tight fit then, and you're better off just angling the panel at 45 degrees.</p>
<p>justForFun's idea [ i think ] was to have direct sun on the panel PLUS reflected light from a mirror to increase output LOL i think you misunderstood the idea trying to be conveyed. JustForFun did not mean for the mirror's light to be the only light applied to the solar panel. personally i thought it was a fantastic idea!!!!!! be well my friends</p>
<p>have you thought about using super capacitors? they charge in seconds</p>
<p>Super caps are nice, but they hold very very very very very very very little amperage compared to even the cheapest AA. Sure, you could get giant soda bottle sized super caps (and spend hundreds of dollars per cap), but thats a bit above and beyond the scope of this. With current technology it's not financially or practically a good solution.</p>
<p>nice and simple, i like it. a question: why don't you add a switch for solar charging? just because when there is no sunlight, the panel will slowly drain the batteries. better to open the circuit when you don't use the panel.</p>
<p>Thats why there is a diode, to prevent drain. A lot of people add switches to this project, no reason why you couldn't. Just not necessary. </p>
ah well okay a diode is a lot better of course :)
I got this circuit board off an LG travel charger . Trying to figure out where I would put the negative and positive wires. I also wanted to add a switch I'm not sure if that would makes things more complicated. Wondering if any of you could help
<p>those looks like a step-down? If they are they will work if you have a big solar panel to step the voltage down to 5vdc. You can get the battery powered usb charge at the Dollarama if you live in Ontario, they are like three bucks!</p>
<p>What the guy above me said. You have a STEP DOWN. You want a STEP UP. Two completely different things.</p>
<p>Does this work with 18650 battery cells?</p>
<p>No, you'd need a charge controller in the mix. At the start of the write up I link to my Lithium Heavy Duty 2.0 project, which uses 18650 lithium battery cells. It's not too much different from this write up.</p>
These look awesome!
<p>What was the problem with this kit? what batteries did you use?</p>
<strong>aa batteries</strong>

About This Instructable




Bio: I used to teach middle school science, but now I run my own online educational science website. I spend my days designing new projects for ... More »
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