Daylight Saving Time begins this weekend, and Louisville firefighters say that means it's time to change smoke detector batteries.Sergeant Salvador Melendez says time changes are the best opportunities to replace batteries because they come every six months, which is the minimum life expectancy of many 9-volt batteries."That basically ensures that you're changing your battery before the life expectancy of that battery has expired, and thus you're always protected," he says.Melendez says it may also be beneficial for families to review their home fire escape plan.