Windows 7 Laptop Battery Issues

Due to a growing amount of chatter on blog sites and the like, Steve Sinofsky, President of the Windows and Windows Live divisions at Microsoft – Head of Windows 7 has posted on the Engineering Windows 7 Blog about the problems.

Having been a user of Windows 7 since Build 7000 – The first Beta, I have had no such problems with the batteries as a result of Windows 7, but as a result of the batteries themselves.

I use a Dell Latitude D630 which is about 18 months old now. From new, I could get about  five hours usable battery life from my extended life 9-Cell Dell battery, however over time (While running XP and Vista) this degraded to about three hours as is to be expected when the laptop is connected to a docking station for the majority of the day. The battery continued to worsen and it got down to about two hours before Build 7000 became available.

During the RC (Release Candidate) phase of the Windows 7 programme, Windows 7 started to show me warnings that my battery was failing and that it was due a replacement, however these where genuine warnings about a battery over 12 months old, which has been thrased by a docking station by day and battery and 90W AC charger at home in the evenings: Needless to say, my laptop gets extensive use.

I have now replaced the failing battery with a new genuine Dell 9-Cell battery and a month old from the replacement, I am still receiving my five hours of life.

I have blogged about this previously in The Myth of Leaving It Plugged In, however Windows 7 includes a very useful application call powercfg. This application includes a command line switch called energy. When run from an Elevated command prompt using the command powercfg /energy a file called energy-report.html is stored in %WinDir%System32energy-report.html.

In my previous post, I highlighted the results of my report showing that my battery was only charging to about 35% of it’s designed capacity. I have just run the energy report again on my laptop and here are the results for my new 9-Cell battery.

Battery:Battery Information

Battery ID: 710SMPDELL DU1399
Manufacturer: SMP
Serial Number: 710
Chemistry: LION
Long Term: 1
Design Capacity: 86580
Last Full Charge: 81641

As you can see, the new battery is charging to very near it’s Design Capacity.

Reviewing the comments on the Engineering Blog, there is a mixture of praise early on for Microsoft being so transparent about their investigations into the issue, but further down it takes a turn for the worse with a user named DanLee81 posting stating that Microsoft have done a bad thing by designing Windows to read the Design Capacity value and not the Total Capacity value.

This is put into context by Pat Stemen of Microsoft who points out that the Total Capacity value fluctuates as the battery is in a charge or a discharge cycle and using that value would provide incorrect data, however DanLee81 attests that using Design Capacity is bad because some batteries report this value as a negative value, null or a zero.

In my eyes, here lies the problem – Poor manufacturing from the battery vendors, and I can only assume from his line of comments that DanLee81 works for one of these said vendors. The resolution to the problem is simple in that battery manufacturers need to ensure that their batteries are carrying the correct data to allow the computers operating system to asses the batteries performance. The majority of batteries do obviously carry this information else Microsoft would not have used it to provide this valuable feature in the operating system. I have no doubts that an investigation into the battery issues being experienced by some users are due to non-genuine or cheaper replacement batteries, which are prone to more premature failure regardless of Windows 7 reporting it.

At least we can replace our PC batteries though.


Richard works as a Cloud Consultant for Fordway Solution where his primary focus is to help customers understand, adopt and develop with Microsoft Azure, Office 365 and System Center. Richard Green is an IT Pro with over 15 years' of experience in all things Microsoft including System Center and Office 365. He has previously worked as a System Center consultant and as an internal solutions architect across many verticals. Outside of work, he loves motorbikes and is part of the orange army, marshaling for NGRRC, British Superbikes and MotoGP. He is also an Assistant Cub Scout Leader.