Batteries are usually not covered by extended warranties. Dead batteries are considered ‘wear and tear.’ This puts it in the same category as oil changes, tires, and brake pad, which usually aren’t covered either.
Batteries don’t last forever and usually must be replaced every four or five years.
However, some batteries will be covered by a manufacturer’s warranty. This is different from the automaker’s warranty, and is a separate warranty directly from the maker of the battery. A battery warrant usually lasts 24 months, although some extend as far as five years.