Laptop batteries, fans and heat

[nickh]

I have noticed most new laptops work as great hairdryers when there is not an ACPI aware OS installed.

This causes problems with battery drain. On my laptop, the battery will last about 30 mins without ACPI throttling, voltage control etc.

Most new laptops use regular desktop CPU cores but rely upon the power management system in ACPI to clock the CPU only when something needs to be done, saving battery drain.

When I initially used my laptop, with Kernel 2.4.17, it lasted around 30 mins on battery. Since I patched and re-compiled the kernel with support for the power control of the chipset and AMD PowerNow!, the battery life was extended to 2.5 hours, a five fold increase. Now longer than what my friends experience with Windows XP on the same model.

I recently compiled a new kernel 2.5. I installed and run my laptop to find it running as cool with the 2.5 series unpatched kernel as with the 2.4 specially patched version. 2.5 is pretty stable and is already being used in some distributions as a production kernel. I would be using it full time if my rangelan wireless driver compiled against it.

Alan Cox has recently announced kernel 2.5 is undergoing the final polishing before release as stable. Major updates and additions are being frozen for the next unstable version.

My laptop runs hot and drains the battery very quickly with knoppix and the 2.4.20 kernel. Knoppix with a 2.5.x kernel and ACPI power management support enabled should extend the battery life 5-fold over the existing Knoppix distribution.

2.4 and 2.5 kernels can run together on the same system. Would it be a good idea to introduce Kernel 2.5 as a boot option on Knoppix, for those with laptops, and to give a chance for the hardware detection programs to introduce support for the up and coming kernel?

[George Wiedmann]

Could you post how you compile 2.5. I have tried a couple of times with no success.

[liechmaster]

i have also tried to compile 2.5.70 - not working(my system won't boot) :/
i have big problem couse my knoppix dont know that my laptop have a battery! (always show that it is on-line) so i dont know how much battery left .

[jduff]

Try the 2.4.22 kernel. It upgrades real easy the Debian way. Acpi is built in there, you just have to activate it. Works fine. Good luck.