The Pick-to-Light devices have been designed to maximize battery efficiency. PTL devices spend most of the time “sleeping”.
With typical use, the two AA batteries could last years. It really depends on how frequently you activate the device.
The battery voltage of each device is continuously monitored by the system.
The device itself always displays the current battery voltage or a low-battery warning. And on the SKU-Keeper server, you can easily get a list of Pick-to-Light devices and their locations that have battery levels below a cut-off value that you specify