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#1 2011-06-30 18:19:31
- pizet
- Member
- From: Slovak Republic
- Registered: 2011-06-18
- Posts: 18
Battery lasting
Hello.
There is a thing about which I am quite concerned. Before installing Arch, I used Ubuntu and Windows 7. On both systems I was able to work with my laptop, without charging the battery, for about 4 - 4,5 hours. Now on Arch (the same laptop), when I am fully charged, "acpi" schows me just 2,5 hours remaining.
Can you help me, what could the problem be?
Thanks for your time.
-pizet
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#2 2011-06-30 18:39:44
- Inxsible
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- From: Chicago
- Registered: 2008-06-09
- Posts: 9,183
Re: Battery lasting
it shows 2.5 hours, but does it last only 2.5 hours as well?
you should check the temperatures of your cpu and make sure that its not running hotter than it used to in ubuntu and/or windows. Use lm_sensors or the like.
There's no such thing as a stupid question, but there sure are a lot of inquisitive idiots !
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#3 2011-06-30 18:48:05
- lifeafter2am
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- From: 127.0.0.1
- Registered: 2009-06-10
- Posts: 1,332
Re: Battery lasting
Also make sure you have set up things like frequency scaling that save on energy.
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#4 2011-06-30 18:53:17
- dolik.rce
- Member
- From: Czech republic
- Registered: 2011-05-04
- Posts: 43
Re: Battery lasting
Hi Inxsible
Hard to say without detailed info, but my best guess would be that the infamous kernel power regression that appeared in kernel 2.6.38. It was very thoroughly covered by Phoronix, see e.g. this article.
What kernel version did you use in the Ubuntu? Or at least tell us what version of Ubuntu was it. If the kernel were older than 2.6.38, than it could explain the difference quite well. Also, did you try to run powertop to if there is any application that takes suspiciously much power?
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#5 2011-06-30 22:35:36
- eduardo.eae
- Member
- From: Reconquista - Argentina
- Registered: 2010-01-24
- Posts: 68
Re: Battery lasting
To me it says 03:40:30 remaining when full. And it lasts for nearly 6 hours. So I don't trust in that acpi's measure.
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#6 2011-07-01 10:02:02
- pizet
- Member
- From: Slovak Republic
- Registered: 2011-06-18
- Posts: 18
Re: Battery lasting
Thank you, I will try out your suggestions.
What kernel version did you use in the Ubuntu? Or at least tell us what version of Ubuntu was it. If the kernel were older than 2.6.38, than it could explain the difference quite well. Also, did you try to run powertop to if there is any application that takes suspiciously much power?
I had Ubuntu 10.
Do you follow my way? Or just see a black stain swimming in the Milky Way...
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#7 2011-07-02 22:39:19
- R00KIE
- Forum Fellow
- From: Between a computer and a chair
- Registered: 2008-09-14
- Posts: 4,734
Re: Battery lasting
I'd say ACPI does not do any kind of running average or anything similar, it just looks at the current reported remaining capacity and current power usage and does a very simple calculation to determine the remaining battery time, that's not even close to anything meaningful but it's the best that can be done without having something running on the background and averaging the power usage.
The laptop I'm using now used to have (before the battery started dying) an increasing remaining time on battery before it started decreasing, that's the problem of using instant values for some variables.
R00KIE
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