[piecesparts]

Applying the theories of acids and caustics. The acid from a battery is very low on the Ph scale and the soda from baking soda is very high on the Ph scale--so they cancel each other out. I would first kill the acidic effects of the battery acid and then do the naval jelly thing. To seal the metal, I would look at a plastic based material or even get the piece covered with a rubber material like Rhino Lining or any other rubber based bedlliner.