The battery system used in the PTM-4 is standard alkaline AA batteries. The batteries will operate the scoreboard for approximately 50 hours of clock running time, which is the entire season in most cases. A replacement set of batteries for the next season costs about $6.
Contrast this with any other system that uses rechargeable batteries that must be charged before every use. Invariably, someone will forget to plug the unit in and it will die in the middle of an event.
One design goal of the PTM-4 was to have a battery system that required no attention for the entire season. You just take it to the event and use it--no fooling around with "plugging it in". The unique design of the displays and electronics in the PTM-4* makes the outstanding battery life possible.