Turning a drawer phone into a power-failure sensor
2026 · 4 min read
Almost everyone has an old Android phone in a drawer. It still charges, still has a screen, still has a SIM slot. It turns out that's exactly what you need to solve a small but genuinely painful problem: knowing the moment the power goes out somewhere you care about — your home while you're away, an elderly parent's apartment, the freezer in the garage.
Watch the charger, not the battery
The clever bit is what you measure. A charging app would watch whether the battery is filling up — useless once it hits 100%. OutagePing instead watches whether the charger is supplying power at all. The instant mains voltage disappears, the charger goes dead, and the phone knows — even at a full battery.
Alarm first, then call for help
A local alarm is enough if someone's home. If nobody stops it, the phone escalates: a loud siren, then — with the cloud add-on — an SMS to your contacts and an automatic phone call. You find out in minutes, not when you get home to a freezer full of spoiled food.
The hard part: what if the phone dies too?
A blackout often takes the Wi-Fi router with it, and eventually the phone's own battery. So the cloud runs a dead-man's switch: the phone checks in every few minutes, and if it goes silent mid-blackout, the servers alert your contacts anyway. A phone with a mobile-data SIM makes this rock-solid, because cell towers stay powered.