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. |
| • | 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. |
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 electronic 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 built-in hydrometer.
Caution: Refer to Battery Disconnect Caution in the Preface section.
- Disconnect
the battery ground (negative) 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.
- When a battery is found without a green dot visible in the hydrometer
refer to Battery Inspection/Test
.
A battery that has remained in a discharged state for a long period
of time is difficult to recharge or may be permanently damaged.
