nostr:npub1c4sgd346sl9uh7mjhn99xjsu7t8dwm54kl6hxp3k0qyl4kz6v94qh5aqv4 https://www.amazon.com/Roost-PP3-9v-Specialty-Battery/dp/B00ZWQHVP4

I raise you the smart smoke alarm battery which broadcasts its own wifi network and alerts you when your dumb detector goes off.

(I guess the company went bankrupt, good riddance)