What is a sign of corrosion on battery terminals?

The presence of a white or green powdery substance is a classic indication of corrosion on battery terminals. This substance typically consists of lead sulfate or other corrosion products that form as a result of a chemical reaction between the battery acid and the terminal materials. As batteries discharge and charge over time, they can produce gases and moisture that contribute to this corrosion, leading to the buildup of this characteristic residue.

Recognizing this powdery substance is crucial because it can impede electrical conductivity and performance of the battery. If left unaddressed, corrosion can lead to battery failure or decreased efficiency. Regular inspection and maintenance can help prevent severe corrosion, improving overall battery lifespan and functionality.

In contrast, the other options refer to signs that may indicate issues with the battery but are not specific indicators of terminal corrosion. For example, a rusty appearance may indicate rust on external metal parts, while cracks in the casing suggest damage that could compromise the battery's integrity. Pitting on the surface can also be a sign of wear or damage but is not specifically connected to terminal corrosion, whereas the white or green powdery substance directly signals a corrosive environment affecting the battery terminals.