power failure night light

Several mechanisms let a night light come on automatically during an outage: plug-in models that detect loss of mains power and switch on, units with an internal rechargeable backup battery that charges while plugged in and powers the light when unplugged, and lights that use ambient light sensors or motion sensors to decide when to illuminate.

Common power sources are: standard plug‑in (120V) units that run from household current; battery‑powered lanterns that use replaceable cells (examples include D and AA sizes); and plug‑in night lights with a built‑in rechargeable battery that charges while plugged in and provides backup power during an outage.

Emergency lanterns are often marketed with durability features such as impact resistance, water‑ or weather‑resistance, and shockproof construction for outdoor or emergency use. Specific claims vary by model, so check the product specs for exact ratings and test conditions.

Sizes typically range from compact plug‑in or utility lights around 4 inches tall up to portable lanterns about 10–10.2 inches tall, so shoppers can expect roughly a 4 to 10.2‑inch height range depending on style.

Common configurations include 4 D alkaline cells, 4 AA or 8 AA cells (some lanterns accept either), and 4 AA in other utility lights. Some plug‑in night lights instead use a built‑in rechargeable (nonreplaceable) battery that charges while plugged in.

Some plug‑in night lights have a foldable plug and a built‑in rechargeable battery so they automatically light during an outage and can be unplugged and carried as a flashlight. Other designs are made to be removed from the wall and used portably.