Overland

Once you have built the electrical system yourself, the thing you want most is to stop guessing about it. Overland is a shunt, a handful of sensors and an ESP32 that turns the trailer's power system into something I can actually read.

It answers exactly one question well: given what the sun did today and what the fridge is doing right now, how many hours do I have? Everything else on the dashboard is in service of that number.

It has to survive with no internet, no mains, and an ambient temperature range of about fifty degrees. So it logs locally to SQLite, serves its own dashboard over a local access point, and draws little enough current that leaving it running is never the reason the battery died.