Would you mind sharing what setup you have that lets you get such long battery life?
But get power top installed. Make sure in the 4th screen in power top and make sure all settings are to "good". I made a systemd unit to do this for me know boot. I also installed tlp and have it set it's settings. Some of those cross over into what powertop does.
I set some things on the i915 driver but that will have to wait until baby watch is over.
Does it for me.
The T450s generation (and the generation before it) use ULV processors (ultra low voltage).
The processors used in the T450s generation have a TLP of 15W.
The processors used in the X220 generation have a TLP of 35W.
On the flip side, the processors in the X220 generation (and in the next generation) are powerful, which is a good thing if you need the power and if you have the laptop plugged most of the time.