How to make use of Power Management features
General Information about Power Management features
Note that different distributions and kernels have different results. ThinkPad-365 and 365X used to perform blank, sleep and hibernation well using HW with W95,OS/2,and Linux installed (1998). Later ThinkPads such as 240X,600E,T20 with recent Debian 2.4 kernels and ACPI=off will sleep, (also MDK-2.6 kernels). However, blank and hibernation to disk do not work. Better results are expected with 2.6.11+.
APM vs. ACPI
All older ThinkPads support APM and a lot support ACPI as well (newer Lenovo ThinkPads supports only ACPI), but at different qualities of implementation. Both technologies cannot be used simultaneously. So you'll have to make a choice which would depend very much on the model as well as on the state of ACPI support in the kernel.
On older models you are surely better off with APM, if they feature ACPI at all.
It seems that at least in recent models from the A, G, R, T and X series ACPI generally works fine and is a lot more flexible than APM, but with a lot of them also a Problem with high power drain in ACPI sleep has been experienced.
Please check our APM vs. ACPI success table to find out about APM and ACPI support in specific models.
On the other hand simply switching from APM to ACPI extended my X31 battery runtime from about 3.5h to 4h. This had nothing to do with Dynamic Frequency Scaling which was active in both configurations.
more precise and extended info should be provided here
How to enable certain features
The following links will take you to separate pages dealing with the various topics.
- How to make APM work (Screen Blanking, Suspend to RAM, Suspend to Disk)
- How to make ACPI work (Screen Blanking, Suspend to RAM, Suspend to Disk)
- How to make use of Dynamic Frequency Scaling (Speedstep, Throttling, etc.)
- How to make use of Harddisk Power Management features (Laptop-mode, Spindown, etc.)
- How to make use of Graphics Chips Power Management features (save even more battery power)
- How to use UltraBay batteries (advanced control for a secondary battery)