Getting Better Battery Life w/ Linux?

Nuclear Elephant asks: "After a little hacking, Linux has been running great on my Thinkpad T30 for about a year now. I can talk to my cellphone and bluetooth devices, do all kinds of neat hacking on wireless, and just about everything you'd expect to be able to do from a Windows machine, except make the battery last. Even after the standard optimizations (like cpufreq, laptop_mode, brightness, turning off useless processes, etc.) my battery still only lasts about an hour running under Linux as opposed to 2 1/2 hours in Windows. Has anybody come up with some innovative battery conservation ideas for Linux? It seems to be the only thing lacking in this fine operating system." What kernel options might one look into, for saving laptop battery power? Also, what desktop settings (both for Gnome and KDE) would work best, for this situation?

Comments

Answered your own question.

[yotaku]

"and just about everything you'd expect to be able to do from a Windows machine, except make the battery last."

Sounds like you basically answered your own question. Use the best tool for the job. If windows allows you to do all that AND make the battery last - then maybe you should just use windows.

Re:Answered your own question.

[elphkotm]

or... he could get a Mac.

Seriously though, Mac's are great. It's UNIX with none of the drawbacks, and is a nice GUI with none of the tedium / lack of power. Fabulous. I suppose this really doesn't help the poster though. So I'll probalby get mod'd Troll or Offtopic.

Re:Answered your own question.

[Anonymous Coward]

Was this seriously just modded troll? I'd say insightful. Off-topic, maybe (that's pushing it), but troll? Sounds like it's the mod who is a troll...

Re:Answered your own question.

[Anonymous Coward]

You're new here, aren't you?

Re:Answered your own question.

[ArmorFiend]

Seriously though, Mac's are great. It's UNIX with none of the drawbacks

You will deserve your troll moderations for this false assertion. Everybody knows MacOS is not free to download like a GNU/Linux system, nor is the code available for modification. Just because it doesn't matter to you, doesn't mean it doesn't matter to everyone.

Re:Answered your own question.

[Skeezix]

Sounds like you basically answered your own question. Use the best tool for the job. If windows allows you to do all that AND make the battery last - then maybe you should just use windows.

He didn't say that Windows lets you do everything Linux can, he said Linux on his laptop can do just about everything Windows can. Linux can also do things Windows can't. :) And really you're missing the point. Many of us have no desire to run Windows or any proprietary operating system. So we want to get the most of our laptop batteries.

Re:Answered your own question.

[RzUpAnmsCwrds]

I always hate this.

Someone asks, "how can I make my > work better"? Someone replys "get a >". Unless the situation is extreme ("how can I make linux run better on my 286?"), the original poster doesn't *want* information on other products. If they had, they would have asked "what notebook should I get?".

Macs may be great little UNIX boxes. I personally have a $300 Armada M300 off of eBay. It is 3.2lbs and very small, PIII 600, 384MB SDRAM, ATI GPU (slow 3D, but fine for 2D), 13GB HDD. It runs about 2 1/2 hours (under Windows). Linux is considerably shorter, perhaps because SpeedStep (that throttles down your CPU voltage and clock) isn't working.

Some people said to turn off graphical effects. This may help, but, in reality, they probably don't make a whole lot of difference.

Here are some tips:
- Get your CPU's clock throttling enabled. I believe that "longrun" can do this. Particularly on AMD CPUs (also on Pentium-M) you can choose 4 different clocks. AMD CPUs can also dynamically adjust their clock based on CPU load (they call it "PowerNow!").
- Decrease your screen brightness. This is a biggie. The backlight sucks a lot of power.
- Disconnect any optical drives (you probably don't have them connected very often anyway)
- Set your HDD spin-down options
- Suspend your computer when you aren't using it
- Charge your computer whenever you can (the less you drain Li-Ion batteries, the longer they last - there is no "memory effect", so *don't* drain them fully)
- Get a new battery or replace the cells in your battery. Many batteries use 18650 cells which can be purchased on eBay for around ~$30 for 8.

Re:Answered your own question.

[trouser]

How would buying a Mac improve the battery life on his Thinkpad? You are a crazy person.

Incidentally I have an iBook and I get great battery life under Linux (YDL 3.01). Pretty much the same battery life as I used to get under OS X.

Re:Answered your own question.

[The Bungi]

You will deserve your troll moderations for this false assertion. Everybody knows MacOS is not free to download like a GNU/Linux system, nor is the code available for modification. Just because it doesn't matter to you, doesn't mean it doesn't matter to everyone.

Well now. Aren't you the miguided zealot. Let's see if I can help you. "Unix" is a class of OS you can buy from SCO, Hewlett-Packard, IBM and even Sun. Linux is an OS that's based on Unix, but it is not Unix. Otherwise the SCO FUD has some basis, mmm? Also, do you remember what "GNU" means?

The OP compared OS X to Unix. He's right - OS X is derived from the *BSD line, which is in turn also based on Unix, much like Linux is. Do I really have to go through this? Anyway, the fact that you pay for it or that you don't get the source code has no relevance. Indeed, maybe OS X is what Linux wants to be when it grows up.

But ultimately it is certainly valid to compare Linux and OS X because they're both descendants from the same original Unix.

I'm sure that it matters to you that you can't "download" OS X or get the code, but from a technical and historical standpoint it's a perfectly valid comparison. Whether that clashes with your "free-as-in-whatever" world view is another matter.

So next time you plan on calling someone a "troll" think twice before you post. You might end up looking, well, slightly stupid.

Re:Answered your own question.

[ArmorFiend]

Heh, nice one. I like how you glossed over the fact that the OP was trying to convert a Linux user to MacOS! And also this is just so darling:

Anyway, the fact that you pay for it or that you don't get the source code has no relevance.

Licensing matters. Deal with it.

Re:Answered your own question.

[yamla]

I have used several Mac laptops, both iBooks and powerbooks. I haven't been particularly impressed with the battery life with them. Granted I tend to _use_ the laptops (often spending much of my time compiling) but in my experience, the battery life was no better than with similar Dell ix86 laptops with decent batteries.

That said, it is quite possible (and outside my experience) that these Apple laptops have greater battery life when the system is mostly idle, i.e. doing word processing and the like.

Re:Answered your own question.

[The Bungi]

I like how you glossed over the fact that the OP was trying to convert a Linux user to MacOS!

I'm sure he was reaching for his pocket when he read your insightful post and stopped. Merciful heaven!

Licensing matters. Deal with it.

I'm sure you meant price, not licensing. That's OK though.

Re:Answered your own question.

[Anonymous Coward]

Macs may be great little UNIX boxes

Again, MACS are not UNIX.

Re:Answered your own question.

[Anonymous Coward]

Get your CPU's clock throttling enabled. I believe that "longrun" can do this

Holy shit, I thought that said "Longhorn".

Re:Answered your own question.

[phorm]

Charge your computer whenever you can (the less you drain Li-Ion batteries, the longer they last - there is no "memory effect", so *don't* drain them fully)

I'm not sure if it applies to Li+ - I believe it dos - but many rechargable batteries are cycle-limited. That means that the more often you flip them to charge-mode, battery-mode, charge-mode.. the faster you run out of cycles. Eventually, they just don't charge anymore.

If my previous laptop battery is an example of this, it was charging just fine until one day it just stopped charging/draining at all above about 1-6%

Re:Answered your own question.

[ACPosterChild]

You might need to deep-cycle it (yes, Li+ batteries need that from time to time). It's the circuitry that needs to re-learn what the battery's full charge and discharge levels are.

Re:Answered your own question.

[Anonymous Coward]

Yeah, a single-vendor, single-platform OS running on single-vendor hardware. I left those days back in the Amiga times. On top of that, the hardware quality is vastly overrated (Apple's laptops are made by a Taiwanese ODM, and have suffered all manner of problems - logic board failures, latch breakages, keyboard screen scratches etc.).

Then throw in an OS and one-button pointer device that treats users like they're mentally backward, and you've got something not so attractive at all. Some of us actually need to get REAL WORK done, and not spend time fidding with gumdrop widgets and threatening lawsuits because of another mobo failure.

Apple's computers are OK, but they're nothing special.

Re:Answered your own question.

[Anonymous Coward]

"Indeed, maybe OS X is what Linux wants to be when it grows up"

Whaaaaat? Linux wants to be a single-vendor, single-platform OS? No way. Linux wants no traction in the embedded space or enterprise markets? Linux wants to ignore low-end devices and fill itself with utterly redundant and CPU-hogging "effects", destroying its ability to run on old Pentium boxes and the like?

Do you have ANY idea what you're talking about? Linux can't "want" to be anything, but even if it could, it certainly wouldn't want to be OS X. Linux is going places, and providing freedom - OS X is there to make people buy more Macs, and saturate them in pointless frills, all the time locking them into buying more Macs. You're so far off the mark, it's not even entertaining...

Re:Answered your own question.

[Anonymous Coward]

Yeah I agree. -ab

Use less power

[redog]

If you use and unload kernel modules, wireless NIC, sound card, hotplug, usb etc etc... your laptop should consume a bit less power, also look to see if your laptop supports processor frequency scaleing

Re:Use less power

[Glonoinha]

Just a thought - spend more time at the command line and less time in the GUI. I think Hiro Protaganist pointed that one out about half way through Snow Crash as a way to get the most out of your laptop when you are not connected to the juice.

My favorite line from that book : "I'm sure they'll listen to Reason..."

the usual...

[ajagci]

Have the harddisk spin down (e.g., hdparm, noflushd), dim the screen, lower the processor speed (e.g., longrun). In general, it shouldn't take a lot of effort to get similar battery life using Windows and Linux.

If you buy your machine from a vendor that supports and pre-installs Linux (e.g., emperorlinux.com), they probably will take care of the necessary configuration for you.

Re:the usual...

[kevin lyda]

noatime for your fs options would be good too.

Re:the usual...

[jovlinger]

perhaps build a root ramdisk with the most commonly used apps? Then you could spin down and unmount your hd partitions. 'course you would lose your data if you unexpectedly kill the laptop.

It may be the winmodem, or some other win-peripheral (sp?). IIRC, these load the batter a bit, and if they default to on, that would be a problem.

Re:the usual...

[moro_666]

you should consider investing some money into
more ram, cause avoiding the swapping all the time
will surely help the disk to stay longer in spindowns.
nowaday the kernel can cache most of the files you use
so the bigger ram the bigger cache you will have the less
power it needs to spin

in our office we also noticed that the laptops coolers
are spinning way to much e.g. trying to keep the machine
as cold as possible, you can bring the temperature limits
a bit up (ofcourse don't let the machine burn in hour hands :S), the ventilators use a lot of battery power
so keeping them in spindown will help to save the battery
life.

hope it helps.

Re:the usual...

[fatrat]

You need the "Laptop mode" kernel patch. Google for it. It batches writes to the HD, so if you combine that with some agressive hdparm stuff you can get the hd to spin down.

My laptop can easily spin the HD down for long periods of time if I'm just web browsing (as someone else says, set the on-disk cache to 0KB)

Smller WM

[camelrider]

A WindowManager that uses less cup and graphics horsepower may help with your battery life. IceWM is available in many distros and you can run Gnome or KDE from within IceWM when you need to.

Re:Smller WM

[twistedcubic]

Yeah. When my battery was new (Toshiba Satellite laptop), I got about 2.5 hours in Windows XP but 3.1 hours in Linux with fluxbox. Even better when you're on a plane without a net connection and you can do all your work on a terminal instead of X.

Throttling Down?

[ABaumann]

Well, your windows machine is probably throttling down the processor when you're unplugged. It's possible that your linux machine doesn't do that.

Re:Throttling Down?

[Glonoinha]

I bet you are right on the target. Perhaps go into the BIOS and throttle the CPU back by hand, if possible.

tpctl for thinkpads

[doja]

Since you have a Thinkpad, you should download and install tpctl. It comes with a daemon called apmiser that controls power use according to CPU usage.

Re:tpctl for thinkpads

[aparrish]

Apmiser works really well on my X24. I usually get between three and four hours on a charge, as long as I don't "emerge" and compile any huge Gentoo source packages while it's unplugged.

Graphics card

[ballwall]

I've got a T40, probably the same graphics card as the poster (Mobility Radeon 7500) and I can't figure out how to enable the power saving features under Linux. I know when I'm in windows power saving the vid card gives me a huge longetivity boost life.

Anyone know how to do that with Linux?

Re:Graphics card

[PD]

Those features are probably not supported. There are people working on them, but at best you'll have to compile your own copy of XFree86. I only know this because I spent a couple hours yesterday getting DRI to work on my T30. I read a lot of docs.

Turn Off Eye Candy

[jmt9581]

Definitely try turning off as much eye candy as possible with your WM, whether it's GNOME, KDE, or ratpoison.

:)

Visual and audio effects mean processing time, and CPU time uses battery power. Also look into unloading modules that you aren't using, especially wireless network-related modules.

Alternatively, you could go the way of many /dotters and get a Mac. I'm a Unix geek who just got a used IBook and I love it.

Re:Turn Off Eye Candy

[ArmorFiend]

Visual and audio effects mean processing time, and CPU time uses battery power.

This is not always correct, it depends on what eye candy operations are implemented efficiently on your hardware. For example, suppose you turn on the nvidia cursor shadow extension. Does it take extra power? No, because the nvidia gpu trivially can compute it in hardware for 1/zillionth of a watt. Now suppose someone does write a non-nvidia X extension that emulates this inelegantly by doing lots of screen blits and software alpha blending: now you're talking power drain. I think another example is apple's eye candy transparent windows and whatnot. Since they're in dedicated hardware, I think they're not a major load.

Re:Turn Off Eye Candy

[BigBir3d]

Until the iBook hdd craps out on you and you go to replace it. 35 screws (or so) to get at the hard drive! There was one screw (with a wide enough slot to use a coin to remove the screw) for my ThinkPad 600X.

I must admit, nothing beats OS X though. Too bad there is no x86 port of it...........

Re:Turn Off Eye Candy

[Pieroxy]

Of course, that is all assuming that Linux will cool down the CPU when it's idle. Giving the amounts this guy is talking about (2 1/2 hours vs 1hour), that may very well be the problem.

I know it's not Linux specific but...

[Will2k_is_here]

Don't forget to decrease the brightness and contrast of your display. I found this can add an extra half an hour or so to your battery life.

And, as was hinted at by others, take off anything that will cause your processor to do more work than you need. This means removing big GUI's, and use basic software (like anything but Gnome and KDE, Firefox instead of Mozilla Suite, Mutt instead of Evolution, etc.)

thinkpad utils

[tellurian]

Go get these from Dag's site:

• kernel-module-thinkpad
• tpctl
• configure-thinkpad

HD sleep

[trouser]

Windows and Mac OS X will stop the HD after a period of inactivity. I've never got this working in Linux. The drive sleeps briefly before spinning up again. Maybe writing log messages or accessing the swap partition. Don't know. Anyway, that's probably a small part of the problem.

Re:HD sleep

[jthj]

You could use a loger like metalog which caches writes to reduce the amount of hard drive use. Also setting the noatime option in fstab will reduce writes to do the disk when you are browsing directories. This will not help the fact that the drives always spinning though. To avoid that you would pretty much need to turn of logging which may not be a good idea. Anyway that's just my .02

Read the Mini-Howto -- Esp Syslog section

[Snerdley]

There is the "Battery Powered Mini-HOWTO" up on the Linux Documentation Project site: http://www.tldp.org/HOWTO/Battery-Powered/index.ht ml

Of course, you probably looked there first before you asked Slashdot :)

Seriously, read the section on syslogd(8). In addition to their suggestions, we have also setup a central log server which allows logging to only go over the network, and not to the local disk at all.

If you are in a LAN (or wireless) environment, you might want to consider that although the wireless might cost you more powering the NIC than it would hitting the disk (after you disabled syncing).

Re:Read the Mini-Howto -- Esp Syslog section

[bergeron76]

Why not kill syslogd entirely? If you don't need it running, kill it. It's not a server, and unless you're experiencing failure of some sort; or some other loss of functionality why run syslogd on a notebook/portable. If nothing else, set your console to be /dev/ttyS0 and set your syslogd/klogd to output to the serial port. At least this way you could debug your machine if it started acting funny.

I recommend reading up on some of the tricks that embedded people (like me) use. There are a ton of ways to save power and drive-time.

I've never seen it (in a laptop; but I have it in my car) - it's not hard to replace a hard disk with a CFcard. Use the 2.5" hard disk for media/games/etc... but use a 512 or 1G cfcard for the OS/system. As such you can save a ton of energy by not having drive motors spinning up/down, etc.

Read this

[Spencer Wilson]

LiIon specs: Cell voltage: 3,6 V Energy / mass: 100 Wh/kg Energy / volume: 230 Wh/l max. Energy: 60 Wh Charge temp.: 0 to 45 C (30 to 115 F) Discharge temp.: -20 to 60 C (-5 to 140 F) Storage temp.: -20 to 60 C (-5 to 140 F) I suggest you give this a read. I agree with the other posters. When someone asks for help with something such as this, they aren't looking for something to replace what they already have. You may love Apple, he/she may not. Stick to the problem, and help solve it.

pcmcia

[nri]

service pcmcia stop
service lpd stop
hdparm -E 4 /dev/dvd
hdparm -S 12 /dev/hdaX

Tweak your applications

[vitroth]

Remember that most applications have no awareness of your desire to conserve battery life. In particular, disabling your web browser's disk cache will prevent your disk from spinning up and staying that way when you web surf. Think about what applications you're using, and how you can modify their behavior.

ACPI

[Fluffy the Cat]

One of the single best things you can do is enable ACPI support, which enables higher levels of CPU power saving when idle. This gives me about half an hour of extra battery power, but suspend support is still somewhat flaky.

Re:ACPI

[Anonymous Coward]

With ACPI on Linux, my laptop no longer turns off the LCD's backlight when I close the lid. Is there an easy way to fix that?

It's an nVidia graphics card, which seems to complicate things (the last time I checked, nVidia had not released any info on how to turn off the backlight).

Idiot mods -- look at the two nearest ancestors

[Anonymous Coward]

The topic of this post is "how do I get better battery life in Linux."

Grandparent post -- Run Windows. Got modded down to 0 and rightfully so.

Parent post -- Run OS X. Modded up to +4 interesting?

I know you love Steve Jobs, but come on.. The parent is offtopic.

Lindows for Laptops

[Anonymous Coward]

For no-brain hassle of running Linux on a notebook computer, why not try a distro that's designed specifically for mobile computers?

Such as Lindows for Laptops.

It has built-in power management features and can even be bought pre-installed on a number of machines.

Disclaimer: I don't work for Lindows, I run Windows and I don't even have a notebook computer. But this is the one commercial mobile Linux solution that I've heard of.

I get better battery life with Linux

[Anonymous Coward]

I run Debian on an iBook, and I find that I get about an hour more with Linux than with OS X. Nothing special, just pmud, noflushd, and I put the hard drive to sleep after 5 or 10 seconds depending on usage.

but then again, that's just me :-)

UNIX and Unix

[Discoflamingo13]

OS X is not UNIX. It may be UNIX-like, but it is not UNIX. The OP claimed equality that OS X is UNIX, which is not true. Your assertion that Unix is a marketing brand (UNIX) and not a design philosophy (Unix) is, for all practical purposes, crap.

Re:UNIX and Unix

[The Bungi]

The OP claimed equality that OS X is UNIX

He said "It's UNIX with none of the drawbacks". I don't see how that's unclear. "It's a UNIX-like operating system with a useable GUI and creature comforts". Or are you going to nitpick "UNIX" vs. "Unix" now? LOL!

Re:UNIX and Unix

[jermz]

Reverend Kool? Is that you?

Seriously, calm down. I hope that you never Xeroxed a copy on a Canon copier or used a store-brand Kleenex to blow your nose.

Some brands have become generic terms. Unix is one of them.

Re:UNIX and Unix

[Discoflamingo13]

No, I'm not the annoying guy from comp.unix.admin. My fight fire with fire attitude gets the better of me somtimes, is all.

Inverse results

[consolidatedbord]

I currently run Linux on my Dell Inspiron 8200 and get about 1 hour more battery runtime than in Windows XP or 2000. Stock, with OEM Windows XP I would peak at about 2.5 hours of battery time, as opposed to peak of 3 hours running Linux. I have since used the i8k-tools (obviously not for Thinkpad) to control things like temperature thresholds to trigger the fans. Not sure about your laptop, but mine has 2 fans, so spinning those down if possible saves a lot of battery time. With the fans running at about 5k RPM as opposed to 9K RPM (full speed) I easily save 45 minutes, making my top peak with Linux damn near 4 hours. Your best bet to save battery life would have to be to find some thinkpad-specific software to slow the fans down and speed up at given temperatures. (not sure if that tpctl can do that or not)

iBook

[Anonymous Coward]

I run Linux on an iBook and get 30min longer battery life than in MacOSX. 4.5 hours battery life in Linux while using wireless and compiling XFree form source.... 6 hours w/o wireless and dimmed screen.

If you dont need 3D acceleration for your video then dont use 3D drivers and your battery life will greatly increase.

buy more ram

[Anonymous Coward]

Hard drive usage eats battery faster than your CPU by far. Max out your RAM and use something like noflushd to minimize the number of times your hard drive has to spin up. Those are the easiest ways to increase battery life.

Why not nitpick it

[Discoflamingo13]

The people who own the trademark did (and do, unfortunately), and OS X has failed to be approved by the Open Group, so it is not technically UNIX. FreeBSD, OpenBSD, NetBSD, and any distribution of Linux are not approved either, so they are not technically UNIX. Of course, you're just trolling, so what the fuck does it matter to you?

APCI or APM?

[ErisCalmsme]

You might want to be sure that you have the right power mangament features enabled in your kernel. I had to enable all of the the APCI features myself. You can use dmesg|less to see if your kernel is actually finding the power management feautures that you enabled. But maybe you knew that;) In any event you would see stuff like this:
ACPI: Battery Slot [BAT0] (battery present)
ACPI: Battery Slot [BAT1] (battery absent)
ACPI: Lid Switch [LID]
ACPI: Power Button (CM) [PBTN]
ACPI: Sleep Button (CM) [SBTN]
ACPI: Processor [CPU0] (supports C1 C2 C3, 8 throttling states)

Alas, my laptop is plugged in 90% of the time and I havent used windows on it for more than the time it took to make a debian cd (which I used to build LFS) so I never had time to notice the difference ;)

Good luck!

Fans are not likely the issue

[Andy Dodd]

Given that the default fan thresholds of the 8200 are VERY aggressive w.r.t. power management (i.e. they run the CPU *damn hot* and you should NOT be slowing down the fans compared to the BIOS defaults), I don't think this is the reason for your long battery life with the 8200.

But I can confirm that my battery life with my I8200 is comparable to, if not better than, under Windows.

Power management features I use:

cpufreq (Both speedstep-ich and p4-clockmod as modules - Load speedstep-ich, set the "powersave" governor to step down the voltage/speed, then load p4-clockmod to drop the clock speed even more. I've been running my P4-M 1.7 at 600 MHz lately, it's more than responsive enough for AIM and web browsing.)

nvclock (Does not support mobile chipsets out of the box, but I disabled the code that causes nvclock to not touch mobile chipsets and it works fine on my GeForce 4 Go 440. I'm assuming the devs of nvclock disabled this because it's an overclocking tool and overclocking mobile GPUs is a bad idea, they forgot that mobile users might actually want to UNDERCLOCK their GPUs...)

Get LOTS of memory. Enough to allow you to disable swap. If you have swap enabled, it seems that even with an idle machine, it'll page stuff in/out just enough to FUBAR any attempts to make the HD sleep.

Valid comparison?

[mc_barron]

Taking a wild guess here, but could the reason you don't get the same battery life out of Linux be due to you using more applications concurrently in Linux that in Windoze? It sounds like you have quite a setup on the Linux partition - do you have the same number of programs on the Windows partition that you regularly run?

Let's compare apples to apples. Mine's bigger. MUWAHAHAHA!

PLEASE mod parent and gparent Up!

[hummassa]

noatime is almost always the right answer.

Mac

[vasqzr]

or... he could get a Mac.


He's got a point. The PowerBook G3 (Pismo/Lombard) that came out in 1999, could go 5 hours on a single battery. A friend of mine had one, and I thought my 2.5 hour battery life of my Dell laptop was good at the time.

Dual batteries, 10 hours of use out in the wild.

Re:Mac

[Anonymous Coward]

Or he could stick with reliable IBM hardware (not made by Taiwanese ODMs) and get a ThinkPad X30 - with the add-on battery they have up to 11 hours of battery life.

Yes, 11. Eleven. Long battery life is not a "Mac thing" any more. No, drop-shadows, logic board failures and patronizing one-button devices are.

laptop battery life

[basil montreal]

Until someone writes better power management features into Linux, short battery life is a fact. I don't understand OS software coding well enough to comment intelligently on how to make Linux more efficient, but I do know that there are various hardware fixes you can make. You can get 3rd party batteries that have longer life than the original, or you could get heavier batteries that last longer. Until Linux is more efficient, increasing power (and weight) of your laptop is the only solution I can think of.

Power Management Under Linux

[darkmeridian]

I have linux and ACPI seems to work pretty well. The largest things are:

1. The screen. Blank it if possible (edit XF86Config-4) and use the darkest setting you can see with. Redundant, I know. But pay attention and actually do it.
2. The wireless. The radio sucks up a lot of power. If you are not using the web, turn off the card. (You can use the tx setting for your card to put it into a sleep state.)
3. The hard drive. Use hdparm to shut it down if no one is using it.
4. Suspend. Doesn't work on the Latitude D800 yet in KDE. But quit KDE (set session manager to save your settings) and then suspend/hibernate.
5. Enable Throttle. You have to enable this in the BIOS as well as the kernel. Don't forget to enable the modules you need for your particular laptop and chip/chipset.
6. Enable auto-throttle. Throttling by itself is useless because you won't do it manually. You have to automate it. Download and compile auto-throttle and start it up on boot. The Pentium-M has eight modes, I believe, and autothrottle moves it up and down really nicely. No lag at all. It must have something to do with the pre-emptible kernel in 2.6.3.
7. Don't blast music. This takes up a surprising amount of power.
8. In windows, don't set stuff like anti-viruses and disk defragmenters to automatically start. This isn't really good for your battery life if it starts up.
9. Don't compile programs while on battery. (Duh, right? Stupid me.)

I get 3:15 hours of battery life on a D800 with the screen on the brightest setting and the internet. Under Linux! Battery life isn't just for windows, you know? Just word processing and web browsing. Cool, huh?