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.

Remove these adsRemove these ads by Signing Up

Step 1: What You Need

Picture of 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.

1-40 of 341Next »

sorry, where have u find the usb charging circuit

SeanC54 months ago

What was the problem with this kit? what batteries did you use?

JoshuaR8 SeanC54 months ago
aa batteries
SeanC5 JoshuaR84 months ago

Lithium aa?

Those would explode.

Lithium batteries are NOT rechargable. Lithium-Ion batteries are, but with special controlling hardware. He used Nickel Metal Hydride batteries (Ni-Mh), your standard rechargable ones.

use NiCads if you are not concerned about their self-discharge rate, they have a much higher mAh than their cousin NiMh.

JoshuaZimmerman (author)  waterlubber3 months ago

Rechargeable 1.2V AA batteries. Nothing special.

RodneyMori2 months ago

what happens when the battery is fully charged, nothing is connected but the panel is left out in the sun?

given the cell panel's low amperage, it should be safe to leave them in the sun once they are fully charged.

JoshuaZimmerman (author)  RodneyMori1 month ago

Nothing. It just kind of tops off. Thats why we keep the amperage low enough as to not harm the batteries.

Elmercab1 month ago
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

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!

SeanC54 months ago

What was the problem with this kit? what batteries did you use?

JoshuaZimmerman (author)  SeanC53 months ago

Not enough battery power, not enough solar power. Newer gadgets require more amperage and 2 AAs just doesn't do it any more.

will energizer rechargeable batteries work they are 1400 mAh

they would work, but it will give your device about a 10-15% charge before they drain.

So if i make this will it charge my galaxy s4? Because other comments arent specific

It would charge it but since the energy density of the two AA batteries aren't that high, it would charge your S4 to about 10-17% before the two AA batteries drain.

every time i plug my phone in it shuts off

whats wrong

Probably you've done something wrong with the connections and either there's a short circuit or the voltage is too high/low. Recehck all the connections and/or use another converter.

Will this work for the converter I took it out of a car charger

Nope, thats a STEP DOWN converter which drops the voltage, you need a STEP UP converter to boost the voltage high.

You COULD use it, but you'd need a super super super large solar panel to do so.

Could I use energizer rechargeable batteries they are 1400 mAh
spatuladle1 month ago

Awesome Instructable! I was wondering if this usb charger would work for this project. Please respond as soon as possible. Thanks!


Ok thanks. I will probably try it since I already have it but if it does not work I will probably buy yours. The website I bought it on I says that output current is 500ma. Also what does mA stand for?

JoshuaZimmerman (author)  spatuladle1 month ago

Yes and no. Yes, it can work. No, it probably won't. In my experiences those board put out too little amperage for most phones (these days) to charge with. Newer phones need AT LEAST 500ma to charge off of, and I think those boards do something around 300mA. My iPhone charges off the circuit I use but it won't charge off one of those boards. Shoot, giant Galaxy Phones want around 1A of power to charge off of and often have issues with the circuit I use. (And to get 1A you're better off with Lithium Batteries.)

I saw the exact same project on Kipkay's channel on YouTube.

Guess who he stole the idea from? Kipkay is notorious for poaching other people's projects off of many a DIY site.

My proof of such poaching? Well... I did post this project TWO FULL YEARS before he posted his video.

JeromeC32 months ago
Hi dude ima buy from ur store, cause im doing a charger for sci fair
Psych.2 months ago

Do you have a schematic I can use?

waterlubber3 months ago

I have a few questions:

-Does your step-up voltage device have a power draw when nothing is plugged in;

- How much voltage/amperage do I need to occasionally top off my phone;

-Should I use three batteries (3.6v) and your step-up device or a similar one to get a longer lasting charge? I understand that having more mAh adds capacity, but will 3 batteries in series also increase it because it has more watt-hours?

-Is there a schematic so I can build one of these step-up things myself?


If I am using a 10V solar panel, Do I need to use a voltage regulator?

Boss_man39175 months ago
Is the duracell battery pack a good circuit you can use
What all are components in dc to usb converter
daddyaggie7 months ago

I just ordered and received the DC to USB from your website. I followed the instructions and can get it to charge, but it keeps disconnecting. The phone says "charging" for a few seconds then stops. I can only get it to charge when I kind of push down on the USB cord. Tried with two of my converters and different cords, same results. Any thoughts?

l3w1sw00d7 months ago

Could I use this as the USB Charging Circuit?

l3w1sw00d7 months ago

Could I use this as the USB Charging Circuit?

TiagoV9 months ago

How do you control the battery charge to it don´t overcharge?

6V 80mA Solar Cell

3 AA Holder

3 Rechargeable AA Batteries @ 2600mAh




Shrink Tubing

Laser Cut Enclosure w/ Screws

There is no component to control it!

JoshuaZimmerman (author)  TiagoV7 months ago

You don't need any battery control for AAs as long as you don't throw a lot of amperage at them. Really, for those kinds of larger projects you'd be using a Lithium Battery or Lead Acid in which case you'd need a controller of some kind. Thats why I love AAs. They're so darn simple.

1-40 of 341Next »