Improving battery life.

Mr.Carioca · 02-15-2008, 11:33 PM

I think the title says it all.

I'm using Ubuntu 7.04, so what do you recommend for a better battery life-time?

Thank you so much for reading!

PAix · 02-16-2008, 02:51 AM

Hi, General answer I'm afraid. I'm uncertain if you mean the life of your battery before you can't use it portable - life of single charge, or the overall useful life of the battery - Subtle difference.

The single most important thing with most batteries of whatever technology is to never leave them in a discharged state. To do so will reward you with diminishing performance and an early retirement from general usefulness. Generally speaking a happy battery is one that is exercised regularly and kept charged. From time to time it is a good idea to run the battery down and give it a good charge so that it know where it's limits are. In the bad old days of NiCD radio batteries, if you kept them on trickle charge and only used 10%, you quickly found that you had batteries that would only give you 10%. Fortunately times have changed, but some of the tenets are the same.

For single charge longevity, dim down that display to what is required, it consumes power and switch off the wireless if it is unneeded as that will be consuming too. The leaner and meaner your config is with regard to unnecessary processes accessing the disks then it all helps.

I hope that I haven't been too general or outright boring. Happy hacking.

H_TeXMeX_H · 02-16-2008, 06:01 AM

So, I'm betting what you mean is this:
You have a laptop and you want the batteries to last longer when you're not running on AC current ?

If so, there are several things you can do, in order of effectiveness most to least:
1) Use CPU frequency scaling if your processor supports it, which is usually does

Quote:

Clock scaling allows you to change the clock speed of the CPUs on the
fly. This is a nice method to save battery power, because the lower
the clock speed, the less power the CPU consumes.

2) Look into using laptop-mode

Quote:

Introduction
------------

Laptop mode is used to minimize the time that the hard disk needs to be spun up,
to conserve battery power on laptops. It has been reported to cause significant
power savings.

Installation
------------

To use laptop mode, you don't need to set any kernel configuration options
or anything. Simply install all the files included in this document, and
laptop mode will automatically be started when you're on battery. For
your convenience, a tarball containing an installer can be downloaded at:

http://www.xs4all.nl/~bsamwel/laptop_mode/tools/

To configure laptop mode, you need to edit the configuration file, which is
located in /etc/default/laptop-mode on Debian-based systems, or in
/etc/sysconfig/laptop-mode on other systems.

Unfortunately, automatic enabling of laptop mode does not work for
laptops that don't have ACPI. On those laptops, you need to start laptop
mode manually. To start laptop mode, run "laptop_mode start", and to
stop it, run "laptop_mode stop". (Note: The laptop mode tools package now
has experimental support for APM, you might want to try that first.)

3) Lower screen brightness, for example my $ony laptop can use the 'sony-laptop' module to lower brightness (for $ony laptops only), I'm sure other laptops can do this too somehow (I don't own any, so look around)

Quote:

Backlight control:
------------------
If your laptop model supports it, you will find sysfs files in the
/sys/class/backlight/sony/
directory. You will be able to query and set the current screen
brightness:
brightness get/set screen brightness (an iteger
between 0 and 7)
actual_brightness reading from this file will query the HW
to get real brightness value
max_brightness the maximum brightness value

Sources of all the quotes are the Linux kernel documentation that comes with the kernel source.

dracolich · 02-16-2008, 01:48 PM

In addition to H_TeXMeX_H's response, some easy ways to reduce battery load:

1) Use darker colors. I read somewhere that it's more energy-consuming to display brighter colors.
2) Set the screen saver to something simple, preferably just a blank screen.
3) Use a lighter wm/dm like XFCE or Fluxbox instead of Gnome/KDE.
4) Avoid processor-intensive programs (compiling a new kernel, 3D accelerated apps)
5) Minimize HDD access and file transfers.
6) If possible, avoid using the cd/dvd drive.
7) If you use the battery a lot consider making /tmp a separate partition using tmpfs.

I got some of that from here:
http://www.faqs.org/docs/Linux-mini/...y-Powered.html

normscherer · 02-21-2008, 12:05 AM

Quote:

Originally Posted by dracolich

In addition to H_TeXMeX_H's response, some easy ways to reduce battery load:

1) Use darker colors. I read somewhere that it's more energy-consuming to display brighter colors.
2) Set the screen saver to something simple, preferably just a blank screen.

The screen power is in the backlight. The backlight power varies with the brightness setting you are using. It does not matter what you are displaying with a lcd screen. If you had a crt on your laptop items 1 and 2 might apply but...

YMMV
Norm

dracolich · 02-21-2008, 07:16 AM

Quote:

Originally Posted by normscherer

The screen power is in the backlight. The backlight power varies with the brightness setting you are using. It does not matter what you are displaying with a lcd screen. If you had a crt on your laptop items 1 and 2 might apply but...

YMMV
Norm

It may have been outdated information where I found the suggestion of darker colors. I can't even find it anymore. The idea of a "simpler" screen saver, though, is to put less load on the processor.

dive · 02-21-2008, 10:14 AM

Also I've read that using hibernation or suspension helps because you aren't booting from scratch each time.

cbxzcm · 02-23-2008, 11:27 PM

Check out lesswatts.org . It's a great source of information for lowering your energy usage.