Building a Real-Time Power Outage Monitor with ESP32 and Slack
Never wonder if your power is out again. Using ESP32 to bridge the gap between grid and backup.
The moment of realization happened in Singapore. I was thousands of miles away from home, enjoying a trip, when I went to check my home CCTV footage through my phone. The screen stayed black. "Connection Failed."
The internal monologue of a developer immediately goes to the worst-case scenario: Did the router die? Is there a break-in? Did the server crash?
The reality was much simpler, yet equally frustrating: a power cut. The cameras ran on their internal batteries until they hit 0%, leaving me in a complete information blackout. I didn't know if the power was out for ten minutes or ten hours.
I promised myself I wouldn't leave for another trip without a "Heartbeat" from my home in Amritsar.
The Solution
I needed a non-invasive system (no cutting 220V mains wires), resilient to inverter switchover gaps, and capable of sending instant notifications.
I chose the ESP32 for its built-in Wi-Fi and low power consumption. By pairing it with a Slack Webhook, I created a device that "shouts" the second the grid fails.
The Hardware Stack
To keep things modular and "plug-and-play," I went with:
ESP32 DevKit V1: The brain of the operation.
USB-TTL Converter: This acts as the sensor. It brings the 5V USB signal down to a safe 3.3V for the ESP32 to read.
1000µF Capacitor: Essential for bridging the 20ms gap during inverter switchover. This prevents the ESP32 from rebooting during the transition.
Female-to-Female jumper wires
Some USB data cables
Engineering the "Flicker Filter"
One of the biggest hurdles was electrical noise. GPIO 34 on the ESP32 is an input-only pin and can act like an antenna. Without a solid ground reference, the signal "flickered" between ON and OFF.
I solved this with a two-pronged approach:
Grounding Geometry: Moving the ground wires to the same side of the board to stabilize the reference voltage.
Software Debounce: I implemented a 3-second delay in the code. The system verifies that the power is actually out before sending a Slack alert, preventing false alarms from minor grid fluctuations.
Watch the Journey
I documented the entire process—from navigating the local electronics markets in my city to the final "Production" test where I manually tripped the MCB.
Watch the Documentary: YouTube - Making my first Electronics project
Get the Code: GitHub - esp32-power-alert
Closing Thoughts
Engineering isn't just about writing code for a Jira ticket; it's about solving the small, personal anxieties of life through technology. Now, when I’m on vacation, I’ll know exactly what’s happening at home. Not because I’m checking a camera, but because my home is talking to me.
If you're interested in building this yourself, feel free to reach out or check out the repository!
