Fill a glass with 8 oz. tap water.
Add ¼ tsp. Clorox bleach to the tap water.
Put a 1-inch wide copper pipe in the glass. The copper pipe should stick out of the glass several inches.
Put a 1-inch wide aluminum bar into the water. The aluminum bar should be the same size as the copper pipe.
Wrap electrical wires around the top of the aluminum pipe and the copper pipe.
Wrap the wires around each other. Attach them to a volt meter to determine how many volts your battery is generating. You should generate about 1.5 volts. You will generate more power with more bleach, but the metals will corrode faster.