BatteryScope

Measuring the power from programs it cannot see

The kernel keeps an energy counter for every process, and the app reads it every 15 seconds with no sudo. But root-owned system processes are off limits to that counter, and they can burn real power. A list that left them out would never add up to what the battery was actually losing.

So once a minute the app reads the fuel gauge's own energy total through IOKit, subtracts everything it did measure plus the screen and the idle floor, and fits the remainder as watts per busy core. System processes then carry a measured share, not a fixed guess, and they are marked as estimates in the list. Node and Python processes get named by package and project, parsed from the command line, so the list says which tool is busy rather than showing a bare interpreter.

That fit is honest about its floor. The gauge refreshes its current reading once every 60 seconds, so the tool can tell you what ran during a minute of 20 W, and no shorter spike will show. One stack sample caught Apple's own battery logger looping through process priorities and burning about two cores for a day or more, so an optional root watchdog now restarts it after three minutes above one core.