Pretty good for me:
My battery life is around 10-12 hours (watching video drops to about 6-7 hours) I did the following out of the box:
- Use the Intel graphics exclusively
- TLP
- Powertop adjustments
I also have the screen set at a low pretty brightness level as I find the 9550 screen pretty bright (too bright) at mid-high levels.
SPECS:
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Ubuntu 17.10
Dell 9550 XPS
i7-6700HQ CPU @ 2.60GHz
non-4K screen (doing this will really save your battery)
16GB RAM
Intel® HD Graphics 530 + NVidia
512GB SSD