I've had a great Pentax Spotmatic outfit since 1973. The first couple\nmercury batteries I used lasted somewhere around 10 years each. Then\nmercury batteries were banned in the U.S. and I had to find a\nreplacement which was zinc air cell battery.\n\nThis lasted a year of so. Last fall I experimented with a 1.4 volt air\ncell hearing aid battet because I could buy them at Walmart and didn't\nhave to send away for it.\n\nLasted only a couple months. They came in a package of 4, so I put in a\nnew battery. It didn't work.\n\nIs there anything equal to the original mercury batteries when it comes\nto battery life?