How to Make a rechargeable, solar-powered USB battery

An emergency battery charger for your mobile phone comes in handy, but it's not the ultimate solution; once it's dead it's useless (what a waste). If you want to really get off the metaphorical grid, you can follow the steps in this video to construct a more robust circuit that will not only bail you out of an inconvenient situation but also recharge in between uses. The simple addition of a low voltage solar panel and rechargeable batteries makes this possible. Enjoy!

Parts:

4 x NiMH AAA Batteries

1 x 4 AAA battery holder

1 x Small PV (photovoltaic) solar cell

1 x Diode rated min 5V 500mA

1 x USB cable or cable of your choice

Tools Required:

Soldering Iron

Lead Solder (the kind with flux core is best)

Heavy Shears

Wire strippers

Electrical tape

Tips:

Solder in a well ventilated area on a non flammable surface

ALWAYS WEAR EYE PROTECTION

Check the circuit polarity before final soldering