Time Change = Battery Change! It is that time of the year to replace your smoke detector battery to ensure they are properly working. Smoke is a poison that can kill you. Without working smoke alarms, you may not wake up from the smoke. Home fires at night or when people are sleeping are the most dangerous. Working smoke alarms will alert you if there is a fire and will give you more time to escape. You should also make sure your smoke detector is not older than 10 years and test them monthly.