The Manhattan Beach Fire Department encourages our residents to change the batteries in their smoke detectors when they change their clocks. Daylight Saving Time provides a convenient reminder to change batteries when changing clocks. "A working smoke detector more than doubles a person's chances of surviving a home fire," says Fire Marshall Derek Edmonds. More than 90 percent of homes in the United States have smoke detectors, but one-third are estimated to have dead or missing batteries.