The BEEP base can function more than a year on lithium batteries, be sure to keep voltage above 2.5V (check in the BEEP app > Devices).
Tip: To make replacing batteries possible while the hive is on top of it, place the BEEP base under your hive with the plastic box lid facing down
How to replace the batteries
Take a screw driver of size PH2, or PZ2 and unscrew the 4 screws of the lid of the grey plastic box on your BEEP base.
Replace the batteries of your BEEP base yearly with 2x 1.5V Energizer Lithium AAA.
Place the lid back (make sure the foam is on top of the batteries)
Tighten the screws again