With TLP I was able to extend the battery life of my ThinkPad E595 significantly.
“TLP is a feature-rich command line utility for Linux, saving laptop battery power without the need to delve deeper into technical details.”
https://linrunner.de/tlp/
If you prefer tools with UI, check TLPUI: https://github.com/d4nj1/TLPUI
There is also a repository for it:
sudo add-apt-repository ppa:linuxuprising/apps
sudo apt update
sudo apt install tlpui
When using a ThinkPad, there are specific kernel modules that can be installed.
https://linrunner.de/tlp/installation/ubuntu.html#thinkpads-only
Check with tlp-stat -b
Install with:
sudo apt install acpi-call-dkms tp-smapi-dkms
Another tool to monitor your power usage is PowerTOP:
“PowerTOP is a Linux tool to diagnose issues with power consumption and power management.”
https://01.org/powertop/