Power Saving Techniques
If you don't need infrared support, disable it in the BIOS or shutdown the IrDA® device driver. There are also some IrDA® features of the kernel which are useful for saving power.
PCMCIA services consume much power, so shut them down if you don't need them.
I'm not sure to which extend the backlight consumes power.
As far as I know this device can only bear a limited number of uptime circles. So avoid using screensavers.
If you want do do it anyhow, you may use xset +dpms and xset dpms 0 0 300 This turns the screen off after 5 minutes of inactivity. Works only if the display is DPMS capable.
For some examples to build batteries with increased uptime up to 8 hours look at Adorable Toshiba Libretto http://www.cerfnet.com/~adorable/libretto.html.
For information about APM look at the APM chapter above.
A hacked rclock . Booker C. Bense has hacked the rclock program to include a simple battery power meter on the clock face.
xbatstat. A battery level status checker for Linux and X.
The "noatime" option when mouting filesystems tells the kernel to not update the access time information of the file. This information, although sometimes useful, is not used by most people (do you know that ls -lu gives you the access time?). Therefore, you can safely disable it, then preventing disk access each time you cat a file. Here is an example of a /etc/fstab with this power-saving option: /dev/hda7 /var ext2 defaults,noatime 0 2
hdparm hdparm is a Linux IDE disk utility that lets you set spin-down timeouts and other disk parameters. It works also for some SCSI features.
Mobile Update Daemon This is a drop-in replacement for the standard update daemon, mobile-update minimizes disk spin ups and reduces disk uptime. It flushes buffers only when other disk activity is present. To ensure a consistent file system call sync manually. Otherwise files may be lost on power failure. mobile-update does not use APM. So it works also on older systems.
noflushd: noflushd monitors disk activity and spins down disks that have been idle for more than <timeout> seconds. It requires a kernel >=2.2.11 . Useful in combination with hdparm and mount with noatime option to bring down disk activity.
The Toshiba Linux Utilities are a set of Linux utilities for controlling the fan, supervisor passwords, and hot key functions of Toshiba Pentium notebooks. There is a KDE package Klibreta, too.
At Kenneth E. Harker's page there is a recommendation for LCDproc LCDProc . "LCDproc is a small piece of software that will enable your Linux box to display live system information on a 20x4 line backlit LCD display. This program shows, among other things, battery status on notebooks." I tried this package and found that it connects only to the external Matrix-Orbital 20x4 LCD display http://www.matrix-orbital.com/, which is a LCD display connected to a serial port. I can't see any use for a laptop yet, but you might use it to build a wearable.
Diald: Dial Daemon . The Diald daemon provides on demand Internet connectivity using the SLIP or PPP protocols. Diald can automatically dial in to a remote host when needed or bring down dial-up connections that are inactive.
KDE http://www.kde.org provides KAPM, Kbatmon and Kcmlaptop. Written by Paul Campbell kcmlaptop is a set of KDE control panels that implements laptop computer support functions, it includes a dockable battery status monitor for laptops - in short a little icon in the KDE status bar that shows how much battery time you have left. It also will warn you when power is getting low and allows you to configure power saving options. Similar packages you may find at the GNOME project http://www.gnome.org/ . See the software maps at both sites.
Please see the Battery Powered Linux Mini-HOWTO by Hanno Mueller by <kontakt@hanno.de> for further information.