[ltp] Maximising battery run time

[Uwe Walter]

Hi Tomek.


On Sa, 2005-01-22 at 16:39 +0100, Tomek Jarzynka wrote:
> I've been wondering what steps can be taken to maximise
> the uptime on batteries, on a T40 laptop. Powersave/cpu
> throttling is one obvious factor, how about the others?

(As you already said:)

Use speedstep heavily!

(Throttling is not as effective, but you could stack it on top if you
really want to.)

Reduce display brightness.

Use ACPI and especially take care, C3 gets used (remove uhci_hcd module
if necessary).

Use powersaving features of your graphics driver.
ATI's fglrx seems to use them, for modern radeon versions (Alex? ;-)),
they can be enabled, search the list for "DynamicClocks".

Unload WiFi driver (for madwifi doing "ifconfig ath0 down" is said to
disable the radio, although the light may stay lit).

Deactivate irda and bluetooth (although I would not assume, they eat too
much power).

You could put the HD to standby as often as possible. Use laptop-mode
for that (integrated into current 2.6 kernels). But there are
indications, that this does not help too much. Probably also related to
the usage pattern. If your HD could stay off for a significant amount of
time, it could help.

Ethernet is an interesting question. Of course, unload it if unused, but
more interesting, because the Windows driver has an option to reduce
speed to 10MBps to save power. Personally, I wouldn't care about this
minor stuff.


Volker made some interesting tests:
http://www.sas.upenn.edu/%7Evbraun/computing/T41/power.html


Greetings, UW(e)