O-RING 0780820 - Caterpillar

The battery cables or the batteries should not be removed with the battery cover in place. The battery cover should be removed before any servicing is attempted.Removing the battery cables or the batteries with the cover in place may cause a battery explosion resulting in personal injury.
Turn the start switch to the OFF position. Turn the ignition switch (if equipped) to the OFF position and remove the key and all electrical loads.
Disconnect the negative battery terminal. Ensure that the cable cannot contact the terminal. When four 12 volt batteries are involved, two negative connection must be disconnected.
Remove the positive connection.
Clean all disconnected connection and battery terminals.
Use a fine grade of sandpaper to clean the terminals and the cable clamps. Clean the items until the surfaces are bright or shiny. DO NOT remove material excessively. Excessive removal of material can cause the clamps to not fit correctly. Coat the clamps and the terminals with a suitable silicone lubricant or petroleum jelly.
Tape the cable connections in order to help prevent accidental starting.
Proceed with necessary system repairs.
In order to connect the battery, connect the positive connection before the negative connector.