James O'Neill's Blog

February 18, 2009

Testing Windows 7 on a Laptop ? Try this

Filed under: Windows 7 — jamesone111 @ 11:13 pm

One of the things which comes up from time to time is people saying “I don’t get as much battery life with this new OS as I used to … ” sometimes it is down to the configuration of the OS or its behaviour , but often it is due to the battery aging.

In Windows 7 the PowerCFG utility now sports a /energy switch, this will analyse your machine’s settings. (It needs to be run from an elevated command prompt) and on my Dell it warns me that some of the hardware devices might prevent the machine going to sleep, and that Windows can’t control the screen brightness to manage power.

More interesting though is the data towards the end of the report.

Battery:Battery Information

Battery ID    1997SMPDELL XY1234

Manufacturer: SMP

Serial Number: 1997

Chemistry: LION

Long Term :1

Design Capacity: 86580

Last Full Charge: 55178


Woah! Design capacity 86580 … it says on the battery that the life was 85 Watt Hours , so I’m guessing this is Milliwatt hours, and the last full charge was only 55 Watt hours ?  So my battery held 50% more when new ? I pinched this battery out of another laptop because when the original was 14 months old, and was getting about 30 minutes run time (batteries only get a 1 year warranty, and a new batteries are eye wateringly expensive) – it has had less than a year of active use – although it’s more than year old, so again out of warranty cover.

I’d be fascinated to know what numbers other people get.

This post originally appeared on my technet blog.


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