Add more or replace the once you have but Amazon has their CooWoo 2 Pack Smoke Detectors for only $18.39 right now when you use coupon code PGGYFZET at checkout. These have a 10 year limited warranty and take 9 volt battery with no wiring required.
Keep in mind, Amazon pricing can change at any time! Don’t wait to purchase this deal or it might be gone when you come back!
This item will ship free for all Amazon Prime members. Or, regular members can score free shipping by adding $25 or more worth of eligible items to your cart. You can get a 30-day free trial of Amazon Prime here.