The answer to that question depends on the model of smoke detector you’ve purchased, but probably not. Even units wired into your home’s electrical system use a battery as a backup. And you’ll probably still need to replace these batteries on a semiannual basis. If you don’t, the smoke detector’s low battery alarm probably will start chirping at some point. And if you have the same luck as most people, it’ll start around 3 a.m. So just change the batteries on schedule to avoid this problem, whether your unit is hardwired or not.