Picture of Solar USB Phone Charger with Battery Backup

In this instructable I will show you how to make a solar powered USB charger for your phone or mp3 player. This is item is great because it doesn't always have to be sunny for you to charge you phone or other USB device. The way the circuit is designed lets the solar panel be constantly charging the batteries and by flipping the switch the batteries start to charge your USB powered device.

Hope you like it.

Step 1: Supplies

Picture of Supplies
To make the Solar USB Phone Charger with Battery Backup you will need:

6 volt Solar Panel
4 AA Battery holder
4 AA  Rechargeable Batteries
2 diodes (I used 1n4007 but any will work)
Female USB 
Solder and soldering iron (optional)
2 100 Ohm resistors (only for apple devices)
Heat Shrink (optional)

You can find all of these parts at your local Radio shack.  Lets start making it.
ChandanZ19 days ago
Super cool project, super cool.
CjB21 month ago

So, my female usb, I'm pretty sure it has only 2 data pins. There would be no point in putting the resistors in parallel with a wire because the wire would just short them out. Is there a way to modify the circuit to make it work with the usb I have. I could be over looking the other data points so here's a link to the exact usb I have. Thanks


SuthentT1 month ago
chrisbpr3 months ago

What about using a spare usb car charger ,that way you get voltage regulation and a charge led for a few pounds at the most.

varun999 months ago

can it charge ipads/iphones by changing the usb port

HI. :-) I Made my own schematic with 5v voltage regulator to get 5v voltage output.


now can you add 3 things?

2 leds one after the swch and one after the solar panel

and a usb in for charghing

bootch1 year ago
Having trouble with continuing the charge. Occasionally get a device not supported message. Reason why?
Lars2232 years ago
You wrote that you need a 4AA Batteryholder but I only see a 2AA one. Which one do I need?
mshbi (author)  Lars2232 years ago
Its is a 4AA battery holder. In the picture there are two more AA batteries under it
etirado mshbi1 year ago

how can I prevent overcharge I basically want to know when the batteries are full so I can shut it off or a piece of logic to keep it from overcharging them

geotheos1 year ago
What end of the resistors do you attach to the female USB
Charly_ZA1 year ago
Hi. Thanks for the great tutorial. I'd appreciate it if you could help me with my take on this project. http://www.instructables.com/community/Help-with-a-school-project-on-solar-power/
gsteiner11 year ago
This is Fantastic! Could you make a tutorial/video on how to make a pure solar charger (no battery's.) I think you could use a 4.5v 1w solar cell and instead of a female usb you could use a 3-5v to 5v voltage step-up/inverter.
how long does it take to charge an iphone
xyndaen2 years ago
simple but effective. anyway there may be some improvement. for example i advice germanyum diodes in this project cause of gaining the voltage when it is compared with silisium ones. the other thing i advice is using and capasitors zener diode 5v for the usb connector to stop voltage changes. 10nf is OK. 7805 is also good choice for this kind of circuits.
mshbi (author)  xyndaen2 years ago
Good ideas. Thanks
rmarc2 years ago
Then how does the altoids container shut?
mshbi (author)  rmarc2 years ago
Good question. I can't get it to shut all the way. I would recommend using a different container
jclaudiu2 years ago
is this working? do u have a video on that?