8 stars from more than 1,200 reviews. While many acknowledged its high price, most complimented its performance, compatibility with other smart home devices, and built in night light. ""What I personally like is the ability to know exactly where smoke would be coming from. If I were to be on the fourth floor in the middle of the night, it would say 'there is smoke in the living room'," wrote one reviewer. 99 View at eBayCheck WalmartCheck Amazon?The Roost battery is the best — well, only — option for those who already have smoke detectors, and want to make them “smart. ” That’s because the Roost battery, which is Wi Fi enabled, sends an alert to your smartphone when the siren goes off. The second generation battery looks and acts like the original, but has a much easier setup process. Through the app, which can accommodate a large number of connected batteries, you have the option to silence the alarm for up to 2 minutes, and automatically send an alert to someone else. Additionally, you can link the Roost battery to other smart home products through IFTTT, to, say, turn on your lights when the alarm goes off. The battery is designed to last up to five years, and will work with any smoke/CO alarms that use a 9 volt battery, which includes hard wired alarms with a 9V battery backup. Roost has updated its app so that users can get notified when there is a severe weather alert, such as hail, freezing temperatures, heavy rainfall and snow, and storms and high winds.