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.

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 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.

« Previous41-80 of 360Next »

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
spatuladle4 months 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)  spatuladle4 months 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.

JeromeC35 months ago
Hi dude ima buy from ur store, cause im doing a charger for sci fair
Psych.5 months ago

Do you have a schematic I can use?

waterlubber6 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_man39178 months ago
Is the duracell battery pack a good circuit you can use
What all are components in dc to usb converter
daddyaggie10 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?

l3w1sw00d10 months ago

Could I use this as the USB Charging Circuit? http://www.aliexpress.com/item/A1O4-1A-rechargeable-lithium-battery-charging-board-battery-charger-Mini-USB-interface-module/1816347309.html

l3w1sw00d10 months ago

Could I use this as the USB Charging Circuit? http://www.aliexpress.com/item/A1O4-1A-rechargeable-lithium-battery-charging-board-battery-charger-Mini-USB-interface-module/1816347309.html

TiagoV1 year 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)  TiagoV10 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.

issa.kawar10 months ago

I decided to build a series circuit with a transformer or resistor, a solar panel(6V), and a USB panel (no batteries) in a small plastic box. Am I going in the right direction?

edrisamiry11 months ago
hi can someone please tell me where can I find USB circuit or how can I make a USB circuit idris.amiry@hotmail.com is my email address plzzzzzzzz me great Instructable ;)

HI, great tutorial! I will try it for sure. Solar charger will be great for long trips in mountains or wherever else :) But, is it possible to connect LCD display to show how much power we have got or it will be too difficult?

Thanks in advance for answer :)

I will upload some picture when I did it!

TiagoV1 year 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!

Mr_Rep1 year ago

so...i need to see if this works, since he said that 6v is inneficent. i gutted a cheap cigarette lighter usb charger, and plan on linking up a 4x AA battery holder for power storage. i want to use a 6v .5W solar cell to receive power from the sun. Is this an unsmart way of going about this? if so, any suggestions? also, say i took 4 normal AA's and stuck them in to charge my device. what level charge will i get?

Mr_Rep Mr_Rep1 year ago

also, i am considering using a 7.2 volt Ni-Mh rechargable battery I yanked of a rather large RC helicopter. how well will this handle? more efficent than 2 or 4 AA's?


electro182 years ago
I bought a 5v solar panel and connected a diode to it....... and connected it to my phone. It was charging well so is there any need of the DC-USB converter?
JoshuaZimmerman (author)  electro181 year ago

I agree. If you want to do direct solar you'd need something akin to 9V at 500mA (or more) and a 5V regulator. The issue is that solar depends on how much sun you're getting. In full sunlight you're probably getting 5V. In anything (and I mean anything) less than 100% full sun you're under 5V. You always want to do 1.5X the solar voltage of what you need, so that even in less sunlight you're getting your minimum.

Would "minty boost" (by adafruit ) serve the purpose ?

Please forgive me, I am NOT trying to be a smart aleck....but to use only a solar panel would be like only eating bologna sandwiches. Your solar panel may not give 5V 100% of the time (e.g. cloudy day, shady area, etc). The IC on the DC-USB converter ensures you will always be pushing 5V. The other items help ensure the quality of the voltage is that of a prime rib. lol
Well, thanks ! but i am not able to find any sort of DC-USB converter ,so is there any way to make it ?
Could you show us how you connected it to your phone?
brburrous made it!1 year ago

Cool looking and easy to make, but not to effective.

JoshuaZimmerman (author)  brburrous1 year ago

Nope, thus why I recommend using lithium batteries if you want to make a daily charger. This is more a "My First Solar Project" or "Student" charger. Cheap, easy to make, and works. Just doesn't work super well due to the AAs and small solar cell.

Animag7711 year ago

I made one very similar to this. I put two 2V solar solar panels connected in series with a diod and attached them to the lid. Wired them to the battery holder and then from there it goes to my 2V-5V DC 1.2A USB converter. The problem I am having is after it charges my phone up about 20% the batteries have dropped down to about 0.7V which is completely un-usable.

What did I do wrong? Why are my batteries losing voltage?

JoshuaZimmerman (author)  Animag7711 year ago

They're losing voltage because you're using up the "power" inside them. Think of Voltage like water pressure and amperage like the amount of water stored up. If you have a big barrel of water and punch a hole in the bottom you get a strong jet stream coming out. As the amount of water inside decreases the amount of pressure also decreases. Same thing with a battery.

This happens with all batteries. Thus why going with Lithium Batteries over AAs is preferable when building a charger.

GrayAlien1 year ago

I might be wrong but if you cut a square into the top of the altoids can you could hot glue the solar panel facing up inside. Then you would not have to worry about dragging along the solar panel. Also, this would place it in a tight package, and make it easier to carry around in your pocket or purse.

JoshuaZimmerman (author)  GrayAlien1 year ago

You most certainly could, but then you'd lose the fun of it being an Altoids tin. (And really, I highly recommend NOT using an Altoids tin.)

Thus why I switched to a wooden box in my 2.0 update. Makes things far easier.

Quick question. I was able to salvage a DC to USB board from a car charger. I actually left the LED on the board for ease of checking if power was flowing or not. I can not seem to get it to light up unless my power source is 9v or greater. In your tutorial your using 2.4 volts of output to charge a device via batteries. I am running a 1watt 6volt panel and it wouldn't light it up either although I was only getting about 3.5 volts due to cloudy weather. Any thoughts?

I tried that at first too... It doesn't work. The USB converting from car chargers are designed to dump 12V DC down to 5V DC, what the op is using is designed to take 2-5V DC and bump it up to 5V DC. You need a different USB converter.

« Previous41-80 of 360Next »