Exercise caution when handling the battery as most cells contain highly corrosive acids that can do significant damage to you or your unit if exposed. Begin by removing the terminal guard before disconnecting the cables. Take out the black battery cable before moving on to the red one. Once the cables have been disconnected, remove the battery from the mower and rinse it with plain water.
Allow the battery to dry before using a wire brush to clean both the terminal ends. Clean until the metal develops a shimmer. Now proceed to apply a thin coating of dielectric lubricant to the terminals before you reinstall the battery.