 Earlier "wet" cells in glass jars used special valves to allow tilt from vertical to one horizontal direction in 1927 to 1931 or 1932.The gel cells were less likely to leak when the portable set was handled roughly.A modern gel battery (also known as a gel cell) is a VRLA battery with a gelified electrolyte; the sulfuric acid is mixed with fumed silica, which makes the resulting mass gel like and immobile.