Batteries are shown in a Roost booth during the 2015 International Consumer Electronics Show (CES) in Las Vegas, Nevada January 4, 2015. The wi-fi enabled replacement batteries for smoke detectors will be able send you a notification if the smoke alarm goes off when you are away and alert the owner when the battery is close to running out. The batteries are expected to be available in the summer of 2015, a representative said. [Photo/Agencies]