First major failure… Yay!
So, I retested the last cell I made, open air… Nothing. I think the aluminum foil was damp. I made a larger one this morning. I glued a paper towel to a piece of aluminum, cut out strips and progressively wrapped pennies up separated by paper towel.
But I think the pennies moved and are shorting inside. This is a little more complicated than I’m looking for, kids are supposed to be able to do this, and it didn’t work so…. On to something else.