Microsoft KB Archive/245107

= Computer Battery Power May Drain Faster with USB Device Attached =

Article ID: 245107

Article Last Modified on 1/25/2007

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APPLIES TO


 * Microsoft Windows Millennium Edition
 * Microsoft Windows 98 Second Edition
 * Microsoft Windows 98 Standard Edition
 * Microsoft Windows 95

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This article was previously published under Q245107



If this article does not describe your hardware-related issue, please see the following Microsoft Web site to view more articles about hardware:

http://support.microsoft.com/default.aspx/w98?sid=460



SYMPTOMS
Battery-powered computers that use Advanced Power Management (APM) or Advanced Configuration and Power Interface (ACPI) may experience increased power consumption leading to a more rapid drain of battery power when a Universal Serial Bus (USB) device is attached.



CAUSE
The bus activity required to maintain communications with the USB device prevents the Central Processing Unit (CPU) from switching to the C3 (Clock-Stopped) power state. When a USB device is not connected, the CPU can spend a significant amount of time in the C3 state, which reduces power consumption and extends battery life.

The option to turn off USB devices after a computer is idle for awhile but still in an active (not standby/suspended) state is not supported in the versions of Windows listed at the beginning of this article



RESOLUTION
For information about a possible resolution for Windows 98 Second Edition, click on the article number below to view the article in the Microsoft Knowledge Base:

297045 The Laptop Computer May Be Unable to Enter the C3 Processor Power-Saving State



WORKAROUND
To work around this issue, try to conserve battery power using any of the following options:
 * Disconnect all USB devices if you are not using them.
 * In the Power Management tool in Control Panel, adjust the power scheme settings to use shorter time-out values for turning off the monitor and hard disks and placing the computer in a system standby state.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

Additional query words: HWUSB HWSYSCPU HWSYSBAT w98standby winme windowsme

Keywords: kbprb KB245107

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