Butlr's recyclable battery lasts between 18-24 months depending on the sensor mode and frames per second. It runs on 3.6v D Lithium thionyl chloride batteries.
Step by Step
Slide the cap by the direction indicated by the “open” icon, you will hear a “click” sound
lift the cap to detach it from sensor body
take out the battery from the housing
place a new battery into the housing, be mindful with the anode and cathode orientation
Close the sensor: put down the cap, then slide in until you hear a “click”