I have installed Ubuntu 20.04 alongside Windows 10.
My battery lasts for more than 3.30 hours in Windows but in Ubuntu it lasts only 1.30 hours.
Install tcl
by the following command that can improve your battery performance.
sudo apt-get install -y tcl-dev
It will automatically start when you turn your PC on.
Ubuntu, unlike Windows, is a free operating system. And behind Windows, there is a huge amount of commercialism and money.
This means that the drivers for your computer have been optimized for low power consumption, when on Ubuntu this is not the case.
Check out this omgubuntu article; you should be able to raise the battery life.
Some hints to reduce power consumption:
Cheer up; Ubuntu is vastly more efficient than Windows in all other aspects.