I have a jailbroken ipod touch 3g, so if it runs out of power i have to re jailbreak it, i use my ipod a lot at school so i made this little charger

Step 1: Tools

tools:
small flat head screwdriver (to take 9v battery apart)
soldering iron
hot glue gun
wire strippers

stuff:
5v regulator (can be found in Meany eletronics, i got mine from a ps1)
usb socket
wire
solder
hot glue
electrical tape
cardboard

Step 2: Take the Battery Apart

remove the cells from the case, the only bits you realy need to keep is case and the battery clip ( i wont go into how to take a battery apart but this is a good gide https://www.instructables.com/id/Free-9V-connector/)

Step 3: Make a New End

take a piece of cardboard and cut it to fit tightly in the end of the battery, then make a hole just about the size of the usb socket, you may also want to take a black pen and color in in

Step 4: Prepare Usb Socket

connect the green/white (d+/d- [pins 2/3]) data lines this tricks newer ipods into thinking that it is a charger

Step 5: Pepare 9v Clip

solder 2 wires to the negative side of the clip and one wire to the positive

Step 6: Add the Regulator

wire up the regulator according to the instructions on the components data sheet, then plug it in and test that you get about 5v (I got 5.10v)

Step 7: Add the Usb Socket

wire up the usb socket red (pin 1) to out of the regulator and black (pin 4) to the spare ground, ounce you have done that plug a battery in to the clip and a ipod to the usb socket and see if it charges (if it catches fire, you did something wrong check wiring and try again)

Step 8: Put It All Togher

take the bit of cardboard you cut and glue the usb plug on, then push the clip down to the end of the battery case and glue it on from the outside, now finally push the end with usb socket into the end of the case and glue it in

Step 9: Finshed

now you can charge your ipod anywhere, this charger will work with 6.5v to about 35v, also with a 9v battery it will only charge four about 20 mins, but i have had success using a small 7.2 v rechargeable battery witch worked for over an hour