The BEEP base works on two 1.5V AAA batteries of any type. We recommend the Energizer L92 Lithium AAA. The internal power converter will convert the battery voltage to 3V. Even when your batteries are down to 1V the BEEP base can still function. The BEEP base is energy efficient and can work for about a year on two AAA batteries.
The table below shows the energy consumption for different measurement and send intervals.