kartoshahv/tapo-voltage-monitor

tapo-voltage-monitor turns a TP-Link Tapo P110 or P115 smart plug into a home voltage meter, so you can find out whether bad mains electricity killed a router, power supply, or other gadget, without buying a separate voltmeter. The official Tapo app only shows watts, but the chip inside the plug also measures voltage, and this program pulls that hidden number out and logs it. Once running, it checks the voltage every few seconds and shows a dashboard in your browser with a live chart and current numbers. Anything outside the normal safe range, 207 to 253 volts for 230 volt countries by default and adjustable for 120 volt countries, gets marked in red and logged as an event with when it happened, how long it lasted, and how far the voltage strayed. It can also spot full blackouts by watching a counter inside the plug that tracks seconds since power returned, so it notices an outage even if your computer was off when it happened. A week of such logs can give you solid evidence to show your electricity provider. Setup takes about ten minutes. You need a Tapo P110 or P115 already connected to your Wi-Fi through the Tapo app, since the cheaper P100 and P105 lack the metering chip, plus any Windows, Mac, or Linux computer on the same network to run the program while it stays awake. After enabling third party access in the Tapo app and finding the plug's local IP address, you download the project, install its Python dependencies, list your plugs in a config file, and store your Tapo account email and password as environment variables so they are not saved in a plain file. On Windows you start everything with one batch file, which opens the dashboard automatically, on Mac and Linux you run two Python scripts by hand. A demo mode can generate fake sample data so you can try the dashboard before owning a plug. The tool is upfront about its limits: readings can be off by a volt or two, it samples every three seconds so extremely brief spikes stay invisible, and the method it uses to read voltage is undocumented by TP-Link, so a future firmware update could break it. Readings are logged locally to a CSV file and never sent to the internet, using an open source library called python-kasa to talk to the plug. It is released under the MIT license.