Hardware accessory

Power outage nudge

USB-mains or UPS sense contact that POSTs power lost/restored to ThermalTrace. Know when the bay went dark — not a freeze probe.

DevicesStale readings Sketch ↗

What it is

  • Does: POSTs { "power1": true } while mains/USB sense is present, false when lost (keys with power/relay import as power sensors).
  • Does not: Keep your ESP32 alive through a blackout by itself. Power the reporter from a UPS or always-on circuit if you need an “outage started” POST; otherwise stale probe detection covers silence when the freeze probe also dies.

Parts

Power nudge parts
Part Why Buy
ESP32 on UPS / always-on Must stay up to report mains loss on another circuit. Adafruit ESP32
USB / mains sense input Opto or relay module: GPIO4 low = power present (active-low in sample). Amazon search

Setup

  1. Flash sketches/arduino/power_sense_ingest/ with Wi‑Fi + ingest URL.
  2. Unplug the sensed USB/mains feed; confirm power1 flips and POSTs.
  3. Combine with freeze probes: outage + cold snap is when pipes are most at risk. Use custom alert rules if you want SMS on power loss alone.

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Related accessories

  • Claim puck — USB presence key: claim a bay with a button press, then show freeze and flood moods on an RP2040-Zero LED.
  • Alert beacon — Desk or hallway mood light that mirrors Bay Buddy freeze/flood moods. Not a temperature probe.
  • Door contact puck — Magnetic reed or button contact that POSTs door open/closed to ingest for drafty-bay moods and custom alerts.
  • Leak contact puck — Water-contact pads that POST wet/dry flood sensors. ThermalTrace auto-alerts when wet once alerts are on.
  • Kit QR & NFC labels — Printable QR stickers and optional NFC tags encoding your push ingest URL for onboarding without typing keys.
  • Probe mount kit — Zip-ties, pipe clips, adhesive pads, 4.7k pull-up, and waterproof DS18B20 mounting notes for a reliable freeze probe.
  • Claim puck case — Enclosure, button, and optional LED diffuser for the RP2040-Zero claim puck — productize the bare board build.

All accessories · Claim puck · ESP32 freeze kit

Power outage nudge FAQ

What it does, what it does not replace, and how it fits ThermalTrace.

What does the power outage nudge post?

JSON like {"power1":false} when sensed mains/USB is lost. The reporting ESP32 should stay on a UPS. Guide: thermaltrace.dev/power-nudge.

What if the freeze probe loses power too?

Stale-reading detection covers silence. The power nudge is for an explicit power1 event when the reporter stays online.

Do I need a custom alert rule?

Optional. Power sensors can drive custom Alerts rules; otherwise use Overview energy cards and stale probe warnings.