Missing Children: There's no kind of indicator that shows Sato's flashlight's battery life, nor are there flashlights to find and collect.
In that case, the batteries will burn out instantaneously, forcing you to find fresh batteries somewhere, which last you the rest of the game. note If you try anyway, your character will state "Well, I tried, but since I can't see, I'm not sure I did it right." And they invariably didn't.
The flashlight in Maniac Mansion comes with old, corroded batteries, that inexplicably last forever unless you are in the one room where the game actually requires you to have a light source to do something, and a Pixel Hunt in the dark won't cut it.
You also use it to read the notebook entries and the map. It's extremely helpful, as it's Always Night after the starting area, and the farther you are from the center of the map, the darker it gets.
Played straight with the flashlight in Kholat.
It was possible to obtain honeylamps that would provide light for a short time, but to fully explore the area and beat the game, it was highly recommended that you obtain an item called the spirit lamp, which provides light for as long as you hold the item.
The obscure 1984 computer game Below the Root (based on Zilpha Keatley Snyder's Green-Sky Trilogy) had an underground area that was pitch-dark.
After you replace them, the fresh batteries last forever.
In Adventure (the text game from 1976) your first set of flashlight batteries will run out fairly quickly.
If you throw a Flash Bomb in a dark cave in Blaster Master Zero, the entire cave will be illuminated for as long as you are in it.
For some reason, you have to use a different flashlight in each cave, but those caves stay lit permanently.
The Who Framed Roger Rabbit game for the NES.
The game adds a completely arbitrary need to waggle the controller to charge it when the light begins to flicker, if only for the illusion of concern the battery might die.
The Last of Us features a never ending flashlight even though it's probably 20 years old.
The flashlight in Tomb Raider Legend lasts a few seconds, while the flashlight in Underworld is indeed infinite.
Admittedly, the game isn't supposed to take that much time, but you still use the flashlight a whole lot.
Luigi's flashlight in Luigi's Mansion never runs out throughout the entire game.
On Zelda II: The Adventure of Link once you get the Candle, all dark caves in the game are automatically lit, through and through.
The Legend of Zelda: A Link to the Past has a lantern that consumes magic to light Ten-Second Flashlight torches, but always lights up the area in front of you just fine.