The CO Detector takes three (3) Energizer AA "UItimate Lithium" 1.5V batteries and has a life expectancy of 3-5 years depending on placement and usage.

To change your CO Detector batteries, twist counter-clockwise to remove the device from its' bracket. Avoid pressing the test button while removing it, as this alert signal can be loud. Press the transparent button on the detector and slide the battery cover back. Then replace the three (3) batteries and slide the detector back into place.