The battery runtime will vary based on individual use case (sport category, brightness setting, scoring frequency). Average users can typically operate the scoreboard continuously between 6 to 10 hours from a full charge. Pressing the small button on side of the battery shows the charging status of battery.  4 LEDs indicate the battery is fully charged. 1 LED indicate the battery is down to 1/4th its capacity. When the battery level is drained to 1/4th capacity, all the LEDs on the scoreboard display will flash once every minute. This flashing prompt indicates that you will have between 30 ~ 60 minutes until the battery is completely drained, again, depending on your brightness setting and usage. If you're near a power source, plug in the AC adapter to simultaneously charge the battery while continue to operate the scoreboard. In doing so, the scoreboard will operate uninterrupted. If a power supply is unavailable, once the battery cells are drained the scoreboard will shut off. Should this happen, the game statistics (scores, clock) will continue to operate normally in the App. If you are in possession of a spare, 2nd battery, swap out the drained battery for a fully charged unit and the App will prompt you to port the game statistics to the scoreboard to continue your game session.  We strongly urge that you purchase a spare, 2nd battery if you will often operate in an environment without access to a power supply.