Users have complained of battery issues - including premature warnings that the power is exhausted, as well as more dire demands to replace the battery - for months, long before Windows 7 went final.
Microsoft claimed that the problem was in the Windows 7 tool that decided when the battery had been drained, or was unable to hold a charge.
"We are investigating this issue in conjunction with our hardware partners, which appears to be related to system firmware (BIOS)," a Microsoft spokeswoman said, referring to the firmware that boots the PC and initialises the hardware components.
"The warning received in Windows 7 uses firmware information to determine if battery replacement is needed."
A very long thread on Microsoft's support site dedicated to Windows 7 battery problems kicked off in early June 2009, and remains active; more than a dozen new messages were posted on this week, for example.
While some users on that thread agree with Microsoft that the warnings are spurious, others believe that the new operating system has permanently crippled their batteries.
"I have tried charging the battery while the computer is off or in another OS, and it does not work," said someone identified as 'DanLee81'.
"It will charge for a few minutes, then stop. The battery will say it's full when it actually only has a few minutes of charge, and when you take out the A/C, it will either last for a few minutes, or completely shut off your laptop. This behavior happens in all [OSes] after Windows 7 damages the battery, not just within Windows 7."
Others reported that their batteries underperformed, even after they abandoned Windows 7 and returned their laptops to running Windows XP or Vista, or switched to Linux .
"Rolling back does not work either," said "Dreklia" in another message. "I feel rip[ped] off!"
In some cases, Windows 7 claimed that brand new laptops were unable to hold a charge.
"Until yesterday it used [to] state that I had 7 hours battery life after a full charge; today after a full charge, it states that I have 4 hours left," said 'tigger1962' of a three-week-old Toshiba Satellite T110.
"I've only had it on now 15 minutes and my charge has now gone down to 2 hours 24 minutes."
Laptop owners are not the only ones who have noticed battery irregularities in Windows 7. Last summer, reviewers for several publications and sites said that Windows 7 slashed battery life by almost a third when compared to XP.
That ran counter to Microsoft's promise that Windows 7 would actually increase battery endurance .
Microsoft said it was looking for a common cause to the battery complaints.
"We are working with our partners to determine the root cause and will update the [support] forum with information and guidance as it becomes available," the spokeswoman said.
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