Battery drains like crazy on Linux

**pdedecker** · 07-Jan-2011, 13:48

openSUSE appears to be using a lot more battery juice than my Windows 7 install. If I can use KDE's power management as an indicator, the battery load drops by 1% every three minutes or so.

That's a little too much for me. How can I reduce my battery usage?

Here are some PowerTop statistics:

I've followed some of PowerTop's suggestions to reduce power savings, but they don't seem to have any significant effect. I haven't dug into PowerTop that much, so I have some trouble interpreting these statistics.

It also caused my wireless keyboard (which is normally not connected to my laptop when on battery) to go to sleep mode and I have to hold a key for five seconds before Linux sees that the keyboard has started sending input. So basically I have to wait five seconds before I can type. The problem seems to have gone away after disconnecting/reconnecting the USB dongle for the keyboard though.

**john_hudson** · 08-Jan-2011, 01:39

I have the opposite experience with Linux more frugal than Windows; have you tried changing the power management settings in KDE?

**techwiz03** · 08-Jan-2011, 02:37

Check your power management settings under KDE as suggested above. It would appear you are not optimized for battery operation. Normally, the battery should last much longer under linux than windows 7 as linux doesn't do the repetitive hdd rewrites that win 7 does. You might also check that your laptop is set to use internal lcd only as if it is set to external monitor plus lcd you will encounter twice as fast battery drain or higher.

**pdedecker** · 08-Jan-2011, 04:27

Originally Posted by john_hudson

I have the opposite experience with Linux more frugal than Windows; have you tried changing the power management settings in KDE?

I have changed some settings such as screen brightness, but most other settings are still set to default. Do you notice anything odd here?

http://i.imgur.com/z0DBv.png
http://i.imgur.com/g1Szj.png
http://i.imgur.com/SGx3P.png
http://i.imgur.com/VY3g3.png
http://i.imgur.com/NOm4W.png
http://i.imgur.com/abp0Y.png

**john_hudson** · 08-Jan-2011, 13:14

The only significant differences are that you have four CPUs and I have one and I don't use suspend to disk - but I don't know whether they would account for your different experience.

Will Honea · 08-Jan-2011, 20:25

techwiz03 wrote:

>
> Check your power management settings under KDE as suggested above. It
> would appear you are not optimized for battery operation. Normally, the
> battery should last much longer under linux than windows 7 as linux
> doesn't do the repetitive hdd rewrites that win 7 does. You might also
> check that your laptop is set to use internal lcd only as if it is set
> to external monitor plus lcd you will encounter twice as fast battery
> drain or higher.

If I may tag on a related question:

If I "Disable" the TV1 display in krandr, does this accomplish turning off
the external output device or do I need to set the BIOS option to "internal
LCD only" to actually kill the secondary display circuitry to realize the
power saving?

--
Will Honea

**techwiz03** · 09-Jan-2011, 01:15

Originally Posted by Will Honea

techwiz03 wrote:

>
> Check your power management settings under KDE as suggested above. It
> would appear you are not optimized for battery operation. Normally, the
> battery should last much longer under linux than windows 7 as linux
> doesn't do the repetitive hdd rewrites that win 7 does. You might also
> check that your laptop is set to use internal lcd only as if it is set
> to external monitor plus lcd you will encounter twice as fast battery
> drain or higher.

If I may tag on a related question:

If I "Disable" the TV1 display in krandr, does this accomplish turning off
the external output device or do I need to set the BIOS option to "internal
LCD only" to actually kill the secondary display circuitry to realize the
power saving?

--
Will Honea

Many laptops have a hotkey designed to direct to lcd, external, or both. All you should need to do is get it into lcd mode. At least my last 5 toshiba's last two hp's and one of my last 2 compaq's worked this way. It is not always the case though as one of my last compaq's had to be done in bios and 3 acers I tried didn't have a way to shut off external display power at all.

**pdedecker** · 09-Jan-2011, 03:38

Originally Posted by john_hudson

The only significant differences are that you have four CPUs and I have one and I don't use suspend to disk - but I don't know whether they would account for your different experience.

Is there a way to collect consumption data from these four CPUs and see if it makes a difference? Or perhaps I could enable some feature that shuts down other CPUs when their task load doesn't justify their power usage?

**brunomcl** · 09-Jan-2011, 22:27

Originally Posted by pdedecker

Or perhaps I could enable some feature that shuts down other CPUs when their task load doesn't justify their power usage?

AFAIK that is not possible due to how windows distribute tasks (it rotates trough the cores). AMD processors had this capability, which worked well with linux, but gave a performance hit when used with windows (the SO would wake the sleeping processors to use then, slowing the processing), so AMD dropped this.

I read the above some time ago, so things may have changed, although I don't think so.

**brunomcl** · 09-Jan-2011, 22:29

P.S.: On a relatively old HP pavillion I have here, the battery duration in vista (when it was installed) and oS was about the same, back when I tested it.