Battery-powered smoke detectors are easy to use. You never have to connect them to a fixed power source in the house. When you choose a smoke detector with batteries, there are different types of batteries that a smoke detector can run on. For example, 3V, 9V, AA, AAA and lithium batteries. Each battery type has its own lifespan. For example, one battery lasts 1 year and the other 10 years. In addition, check if the batteries are replaceable. If not, you can throw away the smoke detector when the battery is empty.