Corroded battery terminals and loose or corroded cable terminals are major causes of hard starting, poor charging-system operation, and power failures on the road. Inspect and clean the terminals twice a year.
With the engine off, first disconnect the cable at the terminal marked Neg or with a minus sign. Then disconnect the other cable. On batteries with top posts, loosen the retaining nut, then twist the terminal back and forth with an upward motion to remove it. If necessary, tap lightly with a wooden-handled hammer to loosen it.
If the terminal still doesn’t come off, use an inexpensive cable terminal puller. With a wire brush, scrub the battery posts and the cable terminals, inside as well as outside, until all the metal looks clean.
On batteries with side terminals, remove the retaining bolt, and the cable will be free. Even though there is little visible corrosion, carefully wire brush the surfaces of the disc-shaped electrical contacts. Refit the cables and tighten the terminals securely.