If your vehicle is showing heavy white or blue crusty corrosion visible on battery terminals, here are the most likely causes and the parts you'll need to fix each one.
Lead-acid batteries naturally vent small amounts of corrosive hydrogen gas during normal operation. Over time, this gas reacts with the metal terminals and clamps, creating a crusty buildup if protective sprays or pads aren't used.
The plastic seal where the metal terminal post exits the battery casing can degrade, crack, or be damaged by over-tightening. This allows liquid battery acid to seep up and directly attack the terminal clamps.
If the battery terminals are not tightened properly after a replacement or recent service, the poor connection creates electrical resistance and heat. This heat rapidly accelerates the chemical corrosion process.
A failing voltage regulator can cause the alternator to supply too much voltage to the battery. This literally boils the battery acid, forcing excessive amounts of corrosive gas and liquid out of the battery vents.