DIY - Very LOW COST emergency charger

Ever thought about making an adventure travel into the wilderness, but not wanting to get rid of your phone, MP3 or GPS? What if the trip takes several days and you've no place to charge your equipment? You could buy a solar charger, which are not that cheap and take really long to charge. You could have a spare batery for your phone, but then again it's not cheap and in some cases it's annoying to make the replacement. Or you could use spare and very low cost parts and build one yourself, giving you the joy of using something self made.

With simple AA chargeable batteries you can give some precious juice to your portable equipment to keep it running. With the benefit that you can charge the batteries again as soon as you get to civilization and you can use as many battery sets as your back can handle.

The AA chargeable batteries provide a maximum voltage around 1.25V instead of the alkaline non chargeable ones (1.5V). Connecting them in serial mode will give your equipment approximately 5V, which is the tension needed for the USB charged devices.

1. micro USB connector ( 1€ )
2. 4 AA battery socket holder ( 0.3 € )
3. 9V battery connector snap ( 0.17 € )
4. soldering connections and silicon glue

Since I couldn't find a place selling a micro USB connector, just bought a cable in a chinese shop and cut the part i needed. After that, the only tricky part is soldering the cables: make sure you connect red with red and black with black. The silicon glue will make the connection isolated and robust since the wires are very thin.

If you want you can even connect several distinct adapters instead of only micro USB.

Another important thing to keep in mind are the batteries capacity! They should be higher than your equipments. For example my Galaxy S has a 1500mAh battery, meaning I've to use at least the same capacity or it won't make a full charge.