While an additional three battery cells will noticeably extend your battery life, you can also extend your battery life by taking a few simple steps to optimize your Linux desktop that will also reduce your power consumption and heat output.
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One of the great power-saving advancements of recent times was Intel's introduction of PowerTOP. PowerTOP is an open-source project sponsored by Intel that analyzes your running system and will make recommendations on changes that can be made to conserve power consumption. With many of the recommendations, PowerTOP is able to automatically make these optimizations as well. This utility also identifies the software components that are causing the most wake-ups, which in turn consume excess power.