Why doesn't the app indicate 12V battery level?

If even one time. I've been left once or twice staring at a jump pack that read 100% a moment ago now reading 0% in less time than it took me to step from the engine bay to the door and reach in and try to start the car.

In my gen 3, I've now taken to disconnecting the battery cable (easy in gen 3, it's right there in the underhood fusebox) if I think the battery might be that drained, then making the car READY with the booster pack, then plugging the battery back in.

That's harder in gen 1 or 2, with no easy up-front way to disconnect the battery, have to get in the hatch. I don't know the story with the newer generations.