Talk:How to reduce power consumption

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Revision as of 17:01, 16 February 2006 by Gsmenden (Talk | contribs) (→‎Best battery discharge times)
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How about linking to this page from the main page?

--Thinker 21:08, 17 Nov 2005 (CET)

Best battery discharge times

With your best power saving, what kind of battery power times are you guys experiencing? The best that I can do with my t43p with the standard (6cell) battery is 2h, and with the ultrabay battery is 1 hour. All of the power saving 'tricks' - hard drive spindown, even adjusting the brightness of my display, has relatively modest effect (~20% max), although CPU throttling definitely reduces power consumption.

In terms of discharge rate, I really can't get below 19,520 mW/h with the hard disk off, wifi on, cpu down to ~700 MHz, and display on minimal brightness with ATI driver power save enabled. In my "normal usage" environment (WiFi on, word processing / non cpu-intensive programming, etc.) I average 21,000 mW/h.

Of note, I have the UXGA display, which might be a huge power guzzler. I have friends with an X40 that claim 5 hours from the 9 cell...

--gsmenden 16:56, 10 Feb 2006 (EST)

ThinkPad T43, SXGA+, undervolted, fan disabled, minimum brightness, disk off, WiFi off, GPU power saving: 13 to 14W, i.e., slightly over 3 hours with a new 6-cell battery. See How to reduce power consumption.

--Thinker 22:46, 10 February 2006 (CET)

BTW, this machine has 1.5GB of RAM, which probably accounts for a large fraction of a Watt. Also, the DVD drive is plugged in. --Thinker 08:39, 16 February 2006 (CET)

Interesting... that would imply ~5W for the bigger screen? That seems high. Could you tell me your basal rate at 700 Mhz by chance? - everything else should match my system (using your fan control v.28 (-thanks!), minimum brightness, disk off, WiFi off, GPU power saving enabled with ATI driver.)

--gsmenden 18:16, 10 Feb 2006 (EST)

The 13-14W figure is with automatic cpufreq scaling and low load, so it's effectively at 800MHz (minimum speed for this 1.86GHz processor). Are you undervolting the CPU too?

--Thinker 00:36, 11 February 2006 (CET)

To my understanding it would seem very unlikely that the higher resolution/bigger display uses a lot more power than lower resolution/smaller ones - except the case that they would have four light tubes instead of one. I'm pretty sure that X series displays have ónly one. Wyrfel 01:20, 11 February 2006 (CET)

for T42 with 14" XGA, ATI 7500 at 80/100MHz, 600MHz@0.7V, hdd off, wifi off, linux: 

 1) min. brightness - 7,6W
 2) brightness is 4 of 7 - 8,6W
 3) max. brightness - 10,1W

2200bg in battery mode consumes ~0,4W. and I bet the iron can go lower runnig windows with native drivers. the only thing I really miss is powerplay support for 7500.

--Bzzt

You mean they nearly doubled the minimal power draw when moving to the T43's Sonoma chipset and Dothan CPU? So you actually get 5-6 hours from a 6-cell battery?! Spooky.

--Thinker 01:42, 11 February 2006 (CET)

well, I'm not sure about 6 hours, but 5h doesn't look hard to achieve. 7,6W is a real bottom here. I couldn't get lower. The regular rate I feel comfort at is rather 10-11W. But even that, 5h is possible with a new 6cell battery.

PS. this is why I returned 2668-4DU back and bought 2373-FWG. Sonoma really sucks, IMHO. I hope Intel has learnt the lesson and the next lines won't so hungry.

-bzzz

Ok - the 15.1" 1600x1200 must be a real power monster, although I have not applied the undervolting patch. I'll give it a whirl when 2.6.15.4 is released.

Update - tried the undervolting patch with some nice results - my lap is noticably cooler, and the fan spends more time off. With only a few process running (no kdm and kde -> only very basic window manager) and a black background text sceen, undervolted down to 700 mV @798 MHz, fan disabled, minimum brightness, hard disk off (standby), WiFi off (ipw not loaded), GPU power saving, DVD unplugged (2nd battery in bay), I can *still* only get down to 17.5 W/h. D'oh!

Still, the screen is worth it if only for the sheer number of women who note, "my, what a nice screen you have" (just one this afternoon. :) It is a strange phenomenon. --gsmenden 21:45, 10 February 2006 (EST)

Haha, good one, gsmenden :)

On my T43 here, I have around 13300mW, when:

  • cstate=C4, 800Mhz, undervolted (0.716V, rather than 0.988V)
  • wifi=off, bt=off, fan=off, brightness=minimum
  • X300 put into "low" mode (it's a 15" SXGA+ screen)
  • pretty "dark" setup (I have basically all-black desktop)

Full charge is around 77000mWh. With, say, 14000mW one should last 5.5 hours on a 9-cell battery.

I can't really say that I see any other obvious venues to pursue to reduce power consumption.

--igorr

igorr, how do you disable wifi? did you try to eject dvd drive?

-bzzz

Disabling wifi can be accomplished by echo 1 > /sys/class/net/eth1/device/rf_kill.

Ejecting the dvd drive? Why would that affect power consumption?

--igorr

yeah, rf_kill does right. if I eject dvd drive or simple type echo eject >/proc/acpi/ibm/bay, I save about 0.4W.

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