What are the green deposits on terminals of the battery?

The green deposits on battery terminals are typically caused by corrosion, often from the buildup of copper sulfate or other compounds. This corrosion occurs when sulfuric acid in the battery interacts with moisture and metals, leading to the formation of these greenish-blue salts. It can hinder the battery's performance by increasing resistance and reducing electrical conductivity. Cleaning the terminals can help restore proper function and prolong battery life.