James O'Neill's Blog

April 20, 2009

Windows7 and batteries, revisited.

Filed under: Beta Products,Windows 7 — jamesone111 @ 10:30 pm

imageI blogged a few weeks back that you could check on the state of your battery from the command line in Win7…

And I said  “I pinched this battery out of another laptop because when the original was 14 months old, and was getting about 30 minutes run time”

My laptop has had to have its motherboard replaced twice recently. First a rather nasty pattern of stripes on the display told the Dell expert my machine had cooked its graphics card (a know issue with this model) and then when I got it back as soon as the machine spun its fan up to full speed there was a click and it powered off – as if it was rather too eager to protect itself from a second cooking. Since I still have access to the other chassis I swapped over the battery and hard disk and used that. All was fine and good, this morning I got my laptop back, popped in the hard disk and away I went  – with the machine on the dead battery. I noticed a red X superimposed on the battery/charge icon, and when I clicked it I got the dialog you can see on the left “Your battery is bad” – pretty sure I haven’t seen that one before. So time to run PowerCfg /energy from an elevated prompt ….

“The battery stored less than 40% of the Designed Capacity the last time the battery was fully charged….  Design Capacity : 57720 ;  Last Full Charge:  21334 (36%)”

What’s interesting is the battery I tried before had a design capacity of 86580 calc – exactly 50% more – which suggests 9 Vs 6 Cells and now in its rather second hand state at 55178 it is more or less the as the other one had when new. Also worrying is that looking round for 3rd party batteries, most of them only seem to be 4400 mah (at 11volts thats 48400 mWH) it would be worse than my existing battery.

This post originally appeared on my technet blog.

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