Extending battery life on X200
Contents
Overview
I own the beautiful Lenovo X200 and run Ubuntu Intrepid on the machine. Its battery life is significantly lower than that under Windows and many users have reported that it runs hotter than under Windows.
With the changes below and a 9 cell battery I get over 9 hours on an idle system with backlight on but at the lowest level and wireless radios off. Before the changes I was only getting 5 hours.
The system also runs a lot cooler and I do not need tpfan (sw fan control for the ThinkPad available here), the built-in hw controller falls back to the lower speeds shortly after a CPU load subsides.
Details
The changes fall into 3 categories:
- Removing packages that create unnecessarily frequent wake up interrupts.
- These interrupts wake up the CPU, preventing it from staying in its most energy efficient state.
- I used Powertop from www.lesswatts.org for this task.
- Lowering the voltage supplied to the CPU.
- Lowering CPU voltage does not impact performance since the clock frequency is unaffected
- I used phc patches and phctools available at www.linux-phc.org for this task.
- Turning off radios you do not need
- My X200 has 3 wireless radios: Wifi, Blutooth, Broadband wireless
