I've had some people get my cells confused with Concentration cell, which are galvanic cells. In no way is my cells a Concentration cell, a Concentration cell uses the same metal like my cells but a Concentration cell uses two different electrolyte that are connected by a salt bridge. My cells are the same metals in the same electrolyte, and the electrolyte is distilled water. The textbooks say my cells should not work but they do. On top of that my cells don't need to be exposed to air or oxygen to work. I find that i get the best life out of my cells when I have the air tight so that no air can come in and so that no water can evaporate out.
As to what determines the positive and negative is still up in the air, I use to think that it was plate size but thats not true anymore. Sometimes the smaller plate is positive and sometimes it negative. It feels like the water determines the positive and negative plates.