Zooka pitching machines do not have power cords. They run solely off of the internal battery. However, if that is a concern, you can have the machine plugged into the battery charger while you pitch. Although the battery will still drain, it will not drain as much, extending the number of pitches before the battery completely dies. Once the battery is completely dead, the machine will not run just on the charger.
Alternatively, you could also purchase a Zooka external battery pack that doubles the capacity of the machine. Just flip a switch and keep on pitching.