Experimenting With Power Conservation
In general, the lower the value you set for each power conservation feature, the longer the battery's charge lasts. On the other hand, setting high values tends to optimize the computer's performance.
To evaluate the way that different settings affect how long you can operate the computer on battery power versus the relative efficiency of how the software performs, experiment as follows:
- Use the computer with all the options set at their default values.
- Use the computer with all the options disabled or set to Off.
- Use the computer with all the options set to their minimum or maximum values.
Using Key Combinations
Table 1 identifies the power management key combinations.
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NOTE: To use key combinations on an external keyboard, enable the External Hot-Key option in the system setup program, and press <Scroll Lock> instead of <Fn>. |
| Feature | Activate/Deactivate |
| Turn off display | To activate,
press <Fn><F1>.
To deactivate, move the cursor or press a key on the integrated or external keyboard. (If nothing happens, the computer may be in suspend or standby mode. Press the power button to resume normal operation.) |
| Suspend (or standby) mode | To activate,
press <Fn><Esc>.
To deactivate, press the power button. |
| Suspend-to-disk mode* | To activate,
press <Fn><a>. (On a French keyboard, press
<Fn><q>.)
To deactivate, press the power button. |
| View battery status icon | Press <Fn><F3>. |
* This key combination does not function under an operating system with the Advanced Configuration and Power Interface (ACPI), such as Microsoft® Windows® 98.
Closing the Display
One way to conserve power on the computer is to close the display when the computer is not in use. When you close the display and an external monitor is not connected, the computer's display shuts off and the computer enters suspend mode (standby mode in Windows 98).
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NOTE: If an external monitor is connected when you close the display, the computer does not activate suspend (or standby) mode. You can still use the external monitor. |
To resume work, open the display. (The computer may take several seconds to resume operation.)
Suspend Mode
If your computer is running the Microsoft Windows 95 or Microsoft Windows NT® operating system, suspend mode stops almost all computer activity, but leaves the computer ready to resume operations immediately in about 20 to 30 seconds. Use suspend mode whenever you leave the computer unattended.
NOTICE: Windows 95 and Windows NT save data to random-access memory (RAM), not to your hard-disk drive, before entering suspend mode. If the computer enters suspend mode while running on battery power, data loss from RAM can occur if the battery discharges completely.
Suspend mode conserves battery power by turning off the microprocessor clock; the display; the hard-disk drive; the CD-ROM, DVD-ROM, or LS-120 drive module (if installed); the external monitor connector; the external keyboard (if attached); the parallel port; the serial port; the touch pad; and the diskette drive.
You can enter suspend mode immediately by pressing <Fn><Esc> (or <Scroll Lock><Esc> on an external keyboard if the External Hot-Key option is enabled in the system setup program).
When you enter suspend mode, the
power indicator is not lit.Resume from suspend mode by pressing the power button. The computer may take several seconds to return to normal operation.
|
NOTES: On resumption from suspend
mode, if a password is set, the computer
displays the password prompt screen.
Suspend mode is known as standby mode under the Microsoft Windows 98 operating system. |
Standby Mode
If your computer is running the Microsoft Windows 98 operating system, standby mode turns off the display, stops the hard-disk drive, and turns off other internal devices so that the computer uses less battery power. When the computer resumes operation from standby mode, the desktop is restored exactly as it was before entering standby mode.
NOTICE: Windows 98 saves data to random-access memory (RAM), not to your hard-disk drive, before entering standby mode. If the computer enters standby mode while running on battery power, data loss from RAM can occur if the battery discharges completely.
You can enter standby mode by pressing <Fn><Esc>.To resume operation from standby mode, press the power button.
Suspend-to-Disk (Hibernate) Mode
Suspend-to-disk (S2D) mode (known as hibernate under the Microsoft Windows 98 operating system) copies all system data to a reserved area—the S2D file—on the hard-disk drive and then turns off all power to the computer. When you resume normal operation, the same programs will be running and the same files will be open that were loaded before you activated this mode.
Place the computer in S2D mode if you intend to store the computer for a month or more.S2D mode preserves the configuration information stored in nonvolatile random-access memory (NVRAM). The reserve battery maintains this information, but it may run out of energy after about a month.
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NOTE: S2D mode helps preserve system data by quickly saving it to the hard-disk drive if you are about to run out of battery power. |
If the
External Hot-Key option is enabled in the system setup program, you can enter S2D mode by pressing <Fn><a> (or <Scroll Lock><a> on an external keyboard). On a French keyboard, press <Fn><q> or <Scroll Lock><q>. |
NOTE: These key combinations do not function under an operating system with ACPI, such as Windows 98. |
Resume operation from S2D mode by pressing the power button.
Some PC Cards may not operate correctly after resuming from S2D mode. If you encounter problems with a card, remove and reinsert the card.
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NOTE: Dell creates an appropriately sized S2D file before shipping the computer to you. Use the Suspend-to-Disk Utility to remove the file, to increase the size of the file, or to add the S2D file if you removed it. For information on creating a S2D file, see "Suspend-to-Disk Utility." |
Power Management Properties for Windows 98
Windows 98 with ACPI provides the Power Management Properties window for setting power conservation features.
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NOTE: Set timeouts and enable hibernate (S2D) mode through the Power Management Properties window rather than through the Power screen in the system setup program. |
To access the Power Management Properties window and set the power management features, perform the following steps:
- Click the Start button, point to Settings,
and click Control Panel.
- Double-click the Power Management Properties
icon.
The Power Management Properties window contains the following tabs:
- Power Scheme — allows you to change individual power management settings or select one of three power mode settings (Always On, Home/Office Desk, or Portable/Laptop) that each provide a set of default power management settings.
- Alarms — allows you to set the Low Battery and Critical Battery alarms to alert you when the battery charge falls below a certain percentage. When you received your computer, the Low Battery and Critical Battery alarm options were not checked. Dell recommends that you do not select these options.
- Power Meter — allows you to view the percentage of battery life remaining when your computer is operating on battery power. If your computer is operating on AC power, the computer displays a message.
- Advanced — allows you to display the Power Meter on the Windows 98 taskbar and to display a password prompt when the computer resumes operation from standby mode. Advanced also allows you to define the action of the Power buttons.
- Hibernate — allows you to enable hibernate (S2D) mode in Windows 98.
Power Management Properties for Windows NT
Dell provides Softex software compatible with the Power Management Controller, which allows you to suspend and resume your portable computer without affecting your ability to use the Latitude LS Advanced Port Replicator (APR).
For information about Softex power management software, see the Softex user’s guides at http://www.dell.com/products/notebook/latitude/NT40.htm and see your Dell-Installed Microsoft Windows NT Workstation Setup Guide.