The system battery maintains system configuration, date, and time information in a special section of memory when you turn off the system. The operating life of the bat- tery ranges from 2 to 5 years, depending on how you use the system (for example, if you keep the system on most of the time, the battery gets little use and thus lasts longer). You may need to replace the battery if an incorrect time or date is displayed during the boot routine along with the following or similar message:
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To determine if the battery needs replacing, reenter the time and date through the System Setup program. Turn off and disconnect the system from the electrical outlet for a few hours, and then reconnect and turn the system on again. Enter the System Setup program. If the date and time are not correct in the System Setup program, replace the battery.
NOTES: Some software may cause the system time to speed up or slow down. If the system seems to operate normally except for the time kept in the System Setup pro- gram, the problem may be caused by software rather than by a defective battery.
If the system is turned off for long periods of time (for weeks or months), the NVRAM may lose its system configuration information. This situation is not caused by a defec- tive battery.
You can operate the system without a battery; however, the system configuration information maintained by the battery in NVRAM is erased each time you shut down the computer. Therefore, you must reenter the system configuration information and reset the options each time the system boots until you replace the battery.
The battery is a
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