Instructables

DIY Solar USB Charger - Altoids

Picture of DIY Solar USB Charger - Altoids
finished2.jpg

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.

 
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Step 1: What You Need

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

Tools:
Soldering Iron
Solder
Tin Snips
Melt Glue Gun and Glue
Tape

Cost is less than $30. I can make one for under $10 when I buy parts in bulk. I have 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.

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One of the IC's could be bad or there could be a bad solder joint.
rweiss1 year ago
Hello,
I am wondering, if we're using some internal batteries (ie. AA in your case), that are wired directly to the solar cell, are they at risk of overcharging if the device is left in the sun?
Thanks for the great tutorial.
nitewing76 rweiss10 months ago
Electronics should never be "left out" in the sun long enough to overcharge the batteries and you should be able to find a solar panel that will fit in the tin. However..."stuff" happens! So I do plan to incorporate a protection circuit in mine.
cnephew11 months ago
When you say "You can rip one out of a cheap USB charger" what exactly do you mean by that?
nitewing76 cnephew10 months ago
Some wall warts and car chargers have a USB connection on them. I assume that is what he's referring to. I'm going to build my own USB-DC converter using AdaFruits Instructable. It calls for a 22uH inductor and I did find a 20uH inductor in a Motorola RAZR charger.
jayc16010 months ago
I tried making with with two recharchable 9v batteries and im not making any headway does it only work with the AA's ? Or do I need to add something in the line to make it work ? im also going to use a plastic pelican case instead of an altoids can just seems a little more rugged.
nitewing76 jayc16010 months ago
Pelican cases are awesome! If you are using 9V batteries you need to add a LM7805 circuit or you risk frying your electronics. But you will be wasting a lot of power and therefore, money. To know more, read AdaFruit's Instructable: http://www.instructables.com/id/MintyBoost!---Small-battery-powered-USB-charger/step2/The-Process-Come-up-with-an-idea/
Fashiondez1 year ago
Hey, does anyone know what to do when you hook everything up, and it is working/shows that the Iphone is plugged in, but it doesn't charge it? Should I cut all the wires and re attach them?
Ever solve this? Same problem.
gowtham7711 months ago
If I rip out a USB Charging Circuit from a cheap charger would it work. I mean the transformer in the circuit is designed to reduce 230volts into 5 volts required for output. But when the input is just 6 volts would it work
henryd1061 year ago
Just how many devices at once could this support?
Is the USB constantly putting out charge? Because a switch would be needed to turn on and off the output, right?
Schmidty161 year ago
can I find another dc to usb converter that is cheap on RadioShack that will work on my iPod or is there a cheaper 1 that I can find in an old device if there is 1 at RadioShack what would it be called?
Schmidty161 year ago
cool thx I have a few questions
Houghie721 year ago
I have got the USB charging circuit from a USB car charger that turns 12v into 5v. Does this mean in order to charge, I have to have 12v going into the USB charging circuit?
On the brown dog gadgets website I found a 6V solar cell, and a 1.5V cell which would be best? I don't completely understand the voltage situation.
ccc21 year ago
I made this, and I am able to charge my simple keypad phone, but I can't seem to charge my ipod touch. I keep getting the message, "charging not supported with this accessory." I am guessing that this is because my ipod needs more power to be charged, but 'm not sure. Any ideas on how I could fix this?
ttawi1 year ago
Hi~ u said "just connect all the red wires with all the black wires", but u r actually connect the red wires to the red wires. i dont know what to do. i think i should connect the postive wire from the solar panel to the postive wire from battery, right?
yoji1 year ago
hello, i have a question. how can we know if the battery is fully charged? and is it possible that battery may explode due to overcharging? how to prevent it?

thanks.
lg902211 year ago
i have a question im new to this but i was wondering can you use the usb circuit found in car chargers? because those are 1.99 compared to the 8.99 dc to usb circuits. i know it takes 12v and drops it to 5v volts but if it receives 6v wont it just drop it to 5v? not really into the whole elctronic thing. or where can i buy cheap dc usb
rev5121 year ago
Hey so it started charging for a few seconds and then my phone said something about my phone is not comparable with this accessory and now it won't charge!?!?
Sorry if this has already been asked, but will this one work with an iPhone 4s?
bulletbkr1 year ago
just a note, if you use hot glue to secure and insulate the connections and wires on the back of you solar cells, be sure to put something under them when you put them in the sun to charge. I now have a ruined dashmat in my truck because the hotglue melted into the fibers as I was charging my batteries. Boo for hot glue. I thought it had a much higher melting point than that.
BillMetrey1 year ago
Hello, I tried to access y our website several times with no success. Are you still accepting requests? I would like to buy at least one of your solar chargers. Thank you!

Bill Metrey
kldtia1 year ago
I attempted this project. I have one question I'm charging a samsung Gs2 phone and I pluged it in. It says it's charging but when I look at the phone it seems like my battery is losing charge. What did I do wrong.

Thanks
budhaztm1 year ago
Would one be able to use lets say a (or a couple) li-po battery for rc airplanes and have a dc-dc converter?
Hello there, me and a friend have a project idea. We are planning to use a 12v battery of arrays of AA rechargeable batteries, also using a 12v panel. Will we need protection against overcharge?
Gigean1 year ago
How do I know if I should use a 4V Solar Panel or something else? Also, where would I find a solar panel, a battery holder, and the diode? This may be the first Instructable project I tackle, so sorry for so many questions
jpman1 year ago
f i use one of those Ipod charger usb thingos would it work??? i really dont have money to buy the minty boost usb circuit i have one of this usb charger things for ipods and phones so yea Email me @ jpaolo.ortega@gmail.com
hi this project is cool so i made 1 with a car charger and it seems to not work any help?
b.t.w im using a 6v solar panel
valiantX1 year ago
In regards to batteries, I think people should try buying some of these new japanese 'water charging', that's right, batteries instead. Excuse my language here, but these batteries can be charged by any form of non-acidic water including urine, sewage water, creek water, your sweat, etc.

Check out the site info right here: http://waterbattery.com/

A cheaper site to buy from: http://shop.conics.net/nopopo-3pk.html
pertamax111 year ago
how much current can be drawn from this dc-usb converter?
agqy28011 year ago
Can rechargeable batteries above 2000mAh - 3000 mAh be used? I managed to find one claiming to be 3500mAh. Plus, the battery claims to be AA Lithium Ion and not NiMh, will that affect anything?
Fashiondez1 year ago
Okay, I finally began putting together the usb solar charger. I got all the supplies from your web, except for the usb circuit board.... I got that out of a cheap usb car charger. Anyways, when I got the solar cells, i wasn't sure what the soldering tabs were and found out the hard way that, without them, it is not really that possible to connect the wires to the glass of the solar cell lol. Anyways, I needed to attach a diode to the positive wire, so i had detached it from the solder tab, and ended up detaching the soldering tab itself (not knowing it was useful...as it wasn't in the picture in the instructions and this was my first time). I am wondering if there is any way to recover my supplies now that two of the tabs are gone.
I hooked up two cells in a series and connected it to two AAs and then those to the circuit board, even tho I am not 100% sure that i am hooking them to the correct place, because it does not have a + or -, so I am just trying to use common sense and I picked a place :). Currently the charger is not working, so i am trying to evaluate. Hope this was understandable.
JoshuaZimmerman (author)  Fashiondez1 year ago
Car charger won't work. A car charger takes 12V from your car battery and lowers it to 5.

The circuit I uses takes 2-3V (such as 2 AAs) and boosts it up to 5.

Two completely different circuits.

I emailed you about all this as well, so check your inbox.
Can you email me the circuit diagram of the DC usb charger? Having a bit trouble with it :) .
yes, thank you. I am pretty sure I got all of yours! I had written you via this and e-mail at first. I don't know if i received a reply to my last one though.
paintphone1 year ago
What was your USB charging circuit originally from?
JoshuaZimmerman (author)  paintphone1 year ago
Surplus from a commercial charger.
I would also like a schematic. It looks simple enough to cobble together.
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