TLP is a free open source, feature-rich and command line tool for advanced power management, which helps to optimize battery life in laptops powered by Linux. It runs on every laptop brand, and ships in with a default configuration already tunned to effectively and reliably maintain battery life, so you can simply install and use it.
It performs power saving by allowing you to configure how devices such as CPU, disk, USBs, PCIs, radio devices should utilize power when your laptop is running on battery.