On a sixty minute full charge, the FunKey S has a median battery life of two hours. Since the device's battery life is impacted by CPU usage and brightness and audio levels, there can be significant deviation from the median by roughly thirty minutes in either direction. In practice, this means that low-intensity emulation such as that of the Game Boy will result in above-average battery life, while high-intensity emulation such as that of the PlayStation will result in below-average battery life. Additionally, the device has a blue LED light that indicates when it is charging, with a battery symbol in the top right corner of the main menu indicating the current charge level. While a low-charge indicator is displayed on-screen before the FunKey S runs out of charge, should this occur, an autosave of the current game is automatically generated prior to shutdown and returned to when the system is recharged and reopened.