Smartphones are so immersed in our everyday lives that it is hard to imagine our routines without them. For most of us, they have already replaced alarm clocks, calculators, organizers, maps, and countless other things. As such, running out of battery charge means losing all of these functionalities, not just the inability to communicate using calls or messages, which itself can already be critical. The widespread usage of mobile devices is accompanied by a growing number of cybercriminals exploring scams for (illicit) benefits. Indeed, the more data flowing through mobile devices and apps, the greater the possibility of exploring threats and attacks. Users are then concerned about unintended access to critical data such as sensitive stored information, bank accounts, passwords, social media accounts, or private files. Although there exist documented strategies to mitigate security risks, the implementation of the corresponding security mechanisms may impose an overhead on energy consumption, which in practice affects the device’s battery charge. In this paper, we analyse the impact that security mechanisms have on energy consumption in the context of Android mobile devices. We investigate the energy consumption of operations such as copying files and logging in with and without encrypting the credentials. Our results quantify the energy overhead of certain security mechanisms and confirm that, in most scenarios, there is a statistically significant increase in energy consumption when security standards, e.g., data encryption, are adopted. However, there are scenarios where the expected increase does not happen. This work highlights the need for understanding the trade-offs between energy consumption and security in mobile devices and serves as a reference for mobile application developers to consider energy efficiency when implementing security measures.