A battery is not designed to last forever. With proper care, however, the battery will provide years of good service. If the battery tests good but still fails to perform well, the following are some of the more common causes:

1. A vehicle accessory was left on overnight.
2. The driving speeds have been slow with frequent stops (stop-and-go driving).
3. The electrical load has exceeded the generator output (particularly with the addition of aftermarket equipment).
4. Existing conditions in the charging system, including the following possibilities:

•	An electrical short

•	A slipping belt

•	A bad generator

•	A bad generator voltage regulator.

5. The battery has not been properly maintained, including the following situations:

•	A failure to keep the terminals tight

•	A failure to keep the terminals clean

•	A loose battery hold down.

6. There are mechanical conditions in the electrical system, such as a short or a pinched wire, attributing to power failure.