Alarms are varied, integrated lighting is color coded based on the type of threat, and the product includes helpful voice alerts when activated. In testing, our phone was alerted almost immediately, and the app couldn’t be simpler to master. If you have additional Nest gear at home such as a Nest thermostat things get even savvier, as you can configure the Protect to shut off your ventilation system if it detects smoke, a potential life saver. First is the concept of the smart battery: Rather than replace the entire alarm, a smart battery simply replaces the 9 volt cell inside your smoke detector. The battery contains a Wi Fi radio that can communicate with your home network and a companion smartphone app. The battery also includes a microphone that listens for the smoke alarm into which it has been installed.