Abandoned Mines? Check.
Post-Digital Apocalypse? Check.
Rusty outmoded, but still Operational 1890's hardware? Oops, Nope.
What about the most popular Cave Lighting system of the 1900's:
Carbide Lamp!
It is waterproof, wind resistant, not electronic, and sturdy and provides a broad illumination with bonus heat.
However, its consumes rare carbide tablets, and *gasp* water also.
This would be perfect to add to mines, natural cave systems, and perhaps outdated und