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:
| • | A vehicle accessory was left on overnight. |
| • | The driving speeds have been slow with frequent stops, stop-and-go driving, with many electrical accessories in use, particularly air conditioning, headlights, wipers, heated rear window, cellular telephone, etc. |
| • | The electrical load has exceeded the generator output, particularly with the addition of aftermarket equipment. |
| • | Existing conditions in the charging system, including the following possibilities: |
| • | The battery has not been properly maintained, including a loose battery hold down or missing battery insulator if used. |
| • | There are mechanical conditions in the electrical system, such as a short or a pinched wire, attributing to power failure. Refer to
General Electrical Diagnosis. |
Electrolyte Freezing
The freezing point of electrolyte depends on its specific gravity. A fully charged battery will not freeze until the ambient temperature gets below -54°C (-65°F). However, a battery with a low state of charge may freeze at temperatures
as high as -7°C (+20°F). Since freezing may ruin a battery, the battery should be protected against freezing by keeping it properly charged. As long as the green eye is visible in the hydrometer, the freezing point of the battery will be somewhere
below -32°C (-25°F).
Battery Protection During Vehicle Storage
Certain devices on the vehicle maintain a small continuous current drain, parasitic load, on the battery. A battery that is not used for an extended period of time will discharge. Eventually permanent damage will result. Discharged batteries will also
freeze in cold weather. Refer to
Battery Inspection/Test.
In order to maintain the battery state of charge while storing the vehicle for more than 30 days:
- Make sure that the green dot is visible in the hydrometer.
Warning: Refer to Battery Disconnect Warning in the Preface section.
- Disconnect the battery ground cable to protect the battery from discharge by parasitic current drains.
When the battery cannot be disconnected:
- Maintain a high state of charge.
- Establish a regular schedule for recharging the battery every 20-45 days.
A battery that has remained in a discharged state for a long period of time is difficult to recharge or may be permanently damaged.
