My son and I made batteries 2 weeks ago.
Use 1/2c water, 1t vinegar, copper wire, galvanized nail. Drill 2 holes in popcicle stick, put nail and wire through it. Place popcicle stick over glass container with water/vinegar in it so both nail and wire are in the solution. Hook voltmeter, + to copper and - to nail.
One made about 0.8v. We made 2 in series and the volts added together and we got about
1.6V.