DIY Solar USB Charger - Altoids

Picture of DIY Solar USB Charger - Altoids
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

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.  I have a kit available at my website 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.
Schmidty1610 months 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?
Schmidty1610 months ago
cool thx I have a few questions
Houghie7211 months 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?
scientist4411 months ago
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.
ccc211 months 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?
ttawi11 months 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?

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.

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 @
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:

A cheaper site to buy from:
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 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.
Quite simple.
So give it to us!
johnestan1 year ago
Could you please tell me what the advantage of having a separate battery charging circuit is. Many of the other instructables use lithium batteries and require a LiPo charger circuit. Is this not needed when using NiMh batteries, or are you just saving money. Is it worse for the batteries in the long run?
JoshuaZimmerman (author)  johnestan1 year ago
Lithium batteries need a charge controller because if their very specific power requirements. NiMh batteries do not.

It's a connivence and price thing when you choose batteries. Lithium are better, but are more expensive and are more work to wire up. NiMh are cheap and easy to use, but are not as effective.

skeys21 year ago
I salvaged a USB thingie from a DC-USB and am using that. It looks just like the one you have pictured; however, I can't seem to fing the negative or positive connections. It would be amazing if I got a response... Thanks!!!
JoshuaZimmerman (author)  skeys21 year ago
They should be labeled. Or marked on the board.

Or you could just take a 2AA battery pack and just touch the wires to the board. If it works, you have things right. If not, switch the positive and negative spots and try again. (Guess and check)
Diggyx171 year ago
Will the solar panel charge the batteries when its not in use???
JoshuaZimmerman (author)  Diggyx171 year ago
Thats the idea.
Diggyx171 year ago
I'm not understanding. how do you know if its just charging from the panel and not the batteries? and when you say "test it" do you mean its going to run off the solar panel and not the batteries?
JoshuaZimmerman (author)  Diggyx171 year ago
Well you can take the batteries out of the setup, then plug in a gadget, then stick it in the sun. If your gadget starts to charge, awesome.

Or you can just stick some batteries in and then plug a gadget in.

Though with this small of a solar cell a lot of USB stuff won't charge directly from the solar cell, they need the batteries in there as well to augment things. (Which is why I have more heavy duty versions of this charger setup with more powerful solar cells.)
ctschoepe1 year ago
Will this work with the newer ipods/iphones? I heard some of them require special circuitry. Also, will the AA batteries recharge from the solar panel or no? And more batteries = more current = faster charging, correct?
JoshuaZimmerman (author)  ctschoepe1 year ago
It works with my iPhone 4. The AAs do in fact recharge from the solar cell (thats the point). More batteries would give you a higher capacity and make things charge faster.

Though to be honest the best solution is 3 AAs in a series to give you 3.6V, but then you'd need about 5V coming in to charge.

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