> Thanks for the awesome write-up.

Glad you enjoyed it. :-)

> I have considered doing something totally ridiculous like setting up a Raspberry Pi with a camera and machine vision software to watch the LED displays on these devices to glean status information. Silly, but...

Ha! I actually have a PoE camera pointed at the display of my UPS. Here's what it looks like right now: https://toroid.org/misc/ups-display.jpg

Notice that horizontal blank row of dead pixels halfway down the right side of the display? The one that makes "54.6" look like "51.6"? That gap defeated my naïve five-minute attempt to use image recognition to extract the battery voltage.