Batteries are a gray zone that went white. Why allowed? Autonomous (not grid-connected). Small (don't tempt toward more). Practical (buggy lantern saves lives).
What Uses Batteries
Buggy lanterns (LED, bright, safe). Calculators (business needs math). Hearing aids (elders, blacksmiths — hearing problems). Clocks (wristwatch for men, wall clock for all). Smoke detectors (after fires — mandatory).
Not on Batteries
Laptops, tablets, smartphones, game consoles, electric razors. Though all run on batteries. Logic: it's not about energy source. It's about what the device DOES. Calculator calculates. Smartphone destroys families.