Solar USB Phone Charger With Battery Backup




Introduction: 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

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.

Step 2: Making It

To make it just follow the circuit diagram as shown. Make sure all of your wires have good electrical connection. If you don't have a soldering iron than you can twist the wires together and cover it with tape. The first circuit shown charges all USB devices except apple devices. To charge all devices including apple products add 2 100 ohm resistors connected to the two data pins on the female USB as shown in the second picture.

If you have any questions then post it in the comments.



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    23 Discussions

    I want to build a solar powered cellphone charger with battery using parts from four to six yardlights. I can't seem to find the specs on the panel. My question is, should I wire the panels in parallel or in series? I think I have a handle on the rest, using your diagram. Your help would be greatly appreciated.

    Rich B


    what is the output voltage and current?

    very simple ill think i make this because for what ever reaason my battery on my tablet dies really quickly.

    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

    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.

    can it charge ipads/iphones by changing the usb port

    now can you add 3 things?

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

    and a usb in for charghing


    4 years ago

    Having trouble with continuing the charge. Occasionally get a device not supported message. Reason why?

    You wrote that you need a 4AA Batteryholder but I only see a 2AA one. Which one do I need?

    2 replies

    Its is a 4AA battery holder. In the picture there are two more AA batteries under it

    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

    What end of the resistors do you attach to the female USB

    Hi. Thanks for the great tutorial. I'd appreciate it if you could help me with my take on this project.

    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

    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.

    1 reply