You can use lemons for batteries ..
18-gauge copper wire
steel paper clip
1. strip off the insulation of copper wire. using the wire clippere , cut a 2 inch piece of bare wire
2. straighten out the paper clip and cut off about a 2 inch piece from the straighten paper clip
3. with the sandpapers , smooth out any rough spots on the ends of wire and paper clip.
4. squeeze the lemon gently , being careful not to break its skin
5. push the wire and paper clip into the lemon. make sure they are close together as possible without touching them
6. touch the tip of your tongue to the free ends of the wire and paper clip . you should feel a slight tingle and taste something metalic