I'm back from Interstate, the battery was two years old that boiled. It had one dead cell at the positive post. The cell always had water even after it boiled, one cell away both directions were lower due to venting. I did add one quart of water to the total battery, no plates were showing. They told me I only needed one new battery, bought one, plus and Multi-Battery Isolator, mine showed heat damage and a hydrometer.