Microsoft KB Archive/263551

= Total Battery Time Is Not Displayed Correctly with Two Batteries =

PSS ID Number: 263551

Article Last Modified on 11/13/2003

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The information in this article applies to:


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Professional

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This article was previously published under Q263551



SYMPTOMS
When you are using two batteries, the displayed total battery remaining time is not correct. Windows 2000 reports a longer remaining time than the real remaining time.



CAUSE
When you are using a laptop computer with two batteries (and you are not using AC power), Windows 2000 does not report accurate total battery remaining time. It reports a longer remaining time than the real remaining time. The computer may shut off with no remaining battery life warning, resulting in a possible data loss. The total battery remaining time is calculated with the following formula (Windows 2000 gets the Remain Capacity and Present Rate values from ASL, and then calculates the remaining time):

RemainingCapacity[mAh]/PresentRate[mA]=RemainingTime[h]

With two batteries, the total battery time should be calculated by the following formula

(RC1+RC2)/(PR1+PR2)=RemainingTime (1)

where:

RC1: Remaing capacity of first battery

RC2: Remaining capacity of second battery

PR1: Present rate of first battery

PR2: Present rate of second battery

However, Windows 2000 calculates the total battery time with following formula:

(RC1+RC2)/PR1=RemainingTime (2)

Windows 2000 should calculate the remaining time with formula 1, not formula 2. Because this problem exists, there is a possibility that the &quot;Power alarm action (lower alarm/critical alarm)&quot; events will not be run at the defined battery remaining settings.

Keywords: kbenv kbHardware kbprb KB263551

Technology: kbwin2000AdvServ kbwin2000AdvServSearch kbwin2000Pro kbwin2000ProSearch kbwin2000Search kbwin2000Serv kbwin2000ServSearch kbWinAdvServSearch

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