We are getting towards the end of the year which is the time when many people change out the batteries in theier smoke alarms. Dead battieries are a major cause of people not being warned of fire in the home. Worst yet many homes lack the proper amount of detectors and many home don't even have one working smoke alarm.
As a Home Inspector I've seen this time after time here in the Reno area. They are relativley cheap and simple to install. No there are even ones that the batteries last the life on the unit. Most people don't realize smoke deterctors have a lifespan of about 10 years.
Again this year the Reno fire department is giving away 600 free smoke alarms during the 2015 Fire Prevention week. Some protect your home and family by checking and installling your own smoke alarms.