OTTAWA — Daylight Savings Time ends this weekend. Besides cranking back your clocks, Ottawa Fire Department Capt. Dennis Nowatzke said you should also change the batteries in your smoke detectors. The batteries should be changed twice a year and the time change is a good time to ensure smoke detectors keeping working, he said. He also said smoke detectors that are 10 years old or more should also be replaced. In cooperation with the American Red Cross, Franklin County residents who can’t afford them can pick up new smoke detectors at the Ottawa fire station for free. State law requires every house to have working smoke detectors on each habitable floor, he said.