This paper presents a user study with 10 blind participants to understand their perception of power consumption in smartphones. We found that a widely used power saving mechanism for smartphones-pressing the power button to put the smartphone to sleep-has a serious usability issue for blind screen reader users. Among other fndings, our study also unearthed several usage patterns and misconceptions of blind users that contribute to excessive battery drainage. Informed by the frst user study, this paper proposes DarkReader, a screen reader developed in Android that bridges users' perception of power consumption to reality. DarkReader darkens the screen by truly turning it off, but allows users to interact with their smartphones. A second user study with 10 blind participants shows that participants perceived no difference in completion times in performing routine tasks using DarkReader and default screen reader. Yet DarkReader saves 24% to 52% power depending on tasks and screen brightness.