How long do contact sensor batteries actually last?

Verified-purchase reviewers and specialist communities widely report 1–2+ years on a single coin or AAA cell for the major brands (Aqara, Eufy, Hue, Tapo). Wi-Fi-only sensors generally underperform on this metric. Cold environments (garages, exterior doors) shorten life noticeably, a pattern that came up in multiple retailer review threads.