[Update 2021-03-12] This solution recently stopped working for me. While looking for a fix, I found that OpenVPN had published some notes↗ on controlling the official OpenVPN Connect app↗ from Tasker. Jump to the Update below to learn how I adapted my setup with this new knowledge.

I recently shared how I use Tasker and Home Assistant to keep my phone from charging past 80%. Today, I'm going to share the setup I use to automatically connect my phone to a VPN on networks I don't control.

A few months ago, I started using the AccuBattery app↗ to keep a closer eye on how I'd been charging my phones. The app has a handy feature that notifies you once the battery level reaches a certain threshold so you can pull the phone off the charger and extend the lithium battery's service life, and it even offers an estimate for what that impact might be. For instance, right now the app indicates that charging my Pixel 5 from 51% to 100% would cause 0.92 wear cycles, while stopping the charge at 80% would impose just 0.17 cycles.