I was on a long flight with only USB power and didn't know if my Mac was draining faster than it charged. So I built a menu bar app - single Swift file, event-driven via IOKit, near-zero CPU. Shows live wattage and warns when your charger can't keep up. (And yes, my charger wasn’t keeping up.) Don’t be surprised by a power deficit!
Show HN: See when your Mac drains battery while charging | Heykuki News