The World Cup balls are charged before every game. The balls used at the World Cup in Qatar have a high-tech sensor which needs to be charged.
The sensor is powered by a small battery, which Adidas said can last for six hours of active use, or up to 18 days when not. The sensor, which weighs just 14 grams, gives ball-tracking in real-time; with cameras positioned around the pitch helping referees to determine offside and other questionable decisions.
Any time the ball is kicked, headed, thrown or even so much as tapped, the system picks it up at 500 frames per second. Data is sent in real time from sensors to a local positioning system (LPS), which involves a setup of network antennas installed around the playing field that take in and store the data for immediate use.
When a ball flies out of bounds during the course of play, and a new ball is thrown or kicked in to replace it, KINEXON’s backend system automatically switches to the new ball’s data input without the need for human intervention.
Source: FIFA