I have used a DC-DC boost converter (or step up converter).
The specifications are:
I/p voltage : 1.5-5 V DC
O/p voltage : 5 V regulated pure DC o/p
* If we use a single cell then we will get o/p current near to 250mA and if we use 2 cells(of 1.5 V each) which makes 3V then we will get 500-600mA of current @ o/p.
I had tried to make this assembly as compact as possible so that it can be used as a portable device.
If we use Duracell Batteries then the results are too good.
Step 1: Collect These Parts...
1. A small Plastic box or case
2. 2*AA size cell holder
3. Battery Snap
4. DC-DC step up or Boost converter Module
5. Holt Glue Gun
7. SPST switch
* I have got my DC-DC boost converter from:
They have got a wide range of similar products too...You can purchase as per your need.You all can also get this from ebay or other leading websites.
Step 2: Assembly Process...
1. First Glue the Cell holder to the plastic case with a hot glue gun
2. Connect a snap to the battery holder and connect the other end of the snap to the i/p of the DC-DC step up module.
3. Make holes for Switch and USB out to charge phone
4. Fix the switch and to hold it firmly tight it with nut-bolts.
5. Spread some hot glue on it
6. Now carefully Fix the DC-DC step up module and then fix it too with the hot Glue.
Step 3: Working of the Charger...
This is an Emergency charger for USB powered devices.You all can buy other similar kind of DC-DC boost converter with high o/p current as per your needs.This charger is suitable for remote areas where we can't depend on the electricity due to load shedding or other reasons.So keep yourself ready with such device for emergency use.AA size batteries are universally used for many applications hence,we can get it anywhere. We can also use rechargeable batteries.
Suggestions and feedback are appreciated...