A battery is not designed to last forever. However, with proper care, 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) with many electrical accessories in use, particularly air conditioning, headlights, wipers, heated rear window, cellular telephone, etc.
3. The electrical load has exceeded the generator output (particularly with the addition of aftermarket equipment).
4. Existing conditions are present in the charging system, including the following possibilities:

•	A slipping belt

•	A bad generator

5. The battery has not been properly maintained. For example, the battery hold down is loose or the battery insulator is missing.
6. 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 in Wiring Systems.

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).

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 a battery state of charge while storing the vehicle for more than 30 days, complete the following actions:

Important: If a green dot is not visible in the hydrometer, test the battery. Refer to Battery Inspection/Test .

1. Ensure the that the green dot is visible in the built-in hydrometer.

Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

2. Disconnect the battery (negative) ground to protect the battery from discharge by parasitic current drains.

When the battery cannot be disconnected, complete the following actions:

1. Maintain a high state of charge.
2. 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 and may be permanently damaged.