Recommendation: Disconnect the battery when repairing electrical equipment and the car's power system.
Lubricate the battery terminals and wire lugs with conductive grease (after installing the tips on the terminals and tightening the nuts), so they don't oxidize.
Warning: When connecting the wires, tighten the ferrule nuts so that the ferrules are firmly seated on the terminal and cannot be pulled off by hand.
Warning: Do not place metal objects on the battery - shorting the terminals may cause a fire.
Loosen the wire lug to the terminal «-» battery by loosening the nut a few turns.
Disconnect the wire end from the terminal «-» and move the wire aside so that the tip cannot touch the terminal.