Awhile back I heard someone saying putting a penny on top of a car battery- like on the plastic- protects the terminals against corrosion.
Now I'm quite familiar with sacrificial anode protection as used to great success in ships and bridges, and galvanized coating. But as I understand it, this requires an electrical connection to the object needing protection, and only protects against liquids which form a continuous contact between the two surfaces.
This isn't a continuous liquid contact scenario, nor is the penny even in electrical contact with the terminal (though it could be). I don't think copper has the high activity level to make an anode versus the lead terminal, but the zinc inside a post-1983 copper clad penny would. Still, the rest of the scenario looks all wrong.
I saw a handful of references in Google to using the penny, yet nobody debunking it. Is this just too obscure a legend to merit a response or could this scenario have some merit to it?