Flashlights

What flashlights are

Called a torch in British English, a flashlight is a light you carry in your hand. LEDs replaced the small incandescent bulbs of older flashlights in the early 2000s.

• The parts: A light source set in a reflector, a clear cover or lens, a battery and a switch, all held in one case.
• Why “flash” light: Early zinc–carbon batteries and carbon-filament bulbs needed frequent rest, so the first lights worked only in brief flashes.
• Everyday carry: Reviewers call small pocket lights EDC flashlights, for everyday carry: sized to go with you everywhere.
• Where they help: Outdoors with no fixed lighting, during power outages, or any time you need light you can move.
• Who makes them: Olight, Fenix, Nitecore, Streamlight, ThruNite, Wuben and Acebeam all appear in 2025–2026 test picks.

How they work

An LED turns battery power into light, and a reflector or lens shapes it into a beam. White LEDs give on the order of 100 lumens per watt; small incandescent bulbs give 8–10.

• A driver circuit: Electronics limit the current through the LED and can hold the output steady as the battery drains.
• Throw and spill: The reflector forms a narrow hotspot, called throw; light that misses it spreads wide as spill.
• TIR optics: Some lights shape the beam with a clear total-internal-reflection lens instead of a mirror.
• Heat step-down: LEDs lose output and life as they heat; Fenix’s PD36R ACE dims itself when it reaches 60 °C.
• Modes and switches: Buttons select output levels, strobe or SOS; a tail switch often gives a momentary burst while pressed.
• Lithium-ion cells: Many pocket lights run on one cell, built in or removable: an 18650 in Olight’s Baton 4 Pro, a 21700 in Fenix’s PD36R ACE.

Types

• Tube EDC lights: Cylinder-shaped pocket lights with a clip, such as Olight’s Baton 4 Pro at 111 mm and Fenix’s PD36R ACE at 146 mm.
• Flat EDC lights: Slim, rectangular bodies that slide into a pocket, such as the Streamlight Wedge and Nitecore EDC29.
• Keychain lights: Tiny lights for a key ring; the Nitecore TINI 2 weighs 0.66 oz and still reaches 500 lumens.
• AA-powered lights: Lights such as the ThruNite Archer 2A V3 run on two AA cells, a common battery that is simple to replace.
• Multi-light tools: Some add UV and a green laser to the white light, such as Olight’s ArkPro Ultra and Nitecore’s EDC17.
• Penlights and headlamps: Penlights are pen-sized, often on AA or AAA cells; headlamps strap to the head and leave both hands free.
• LEP lights: Laser-excited phosphor lights, sold since 2018, light a small spot at very long range.

What to look for

• Lumens: Total light output, measured 30 seconds after switch-on under the ANSI FL1 standard; the top mode may last only seconds.
• Beam distance: FL1 rates it as the distance where the light falls to 0.25 lux, about a full moon, based on peak intensity in candela.
• Runtime: FL1 runtime ends when output drops to 10% of its start, so read the hours for the mode you will really use.
• Water rating: IPX7 means brief immersion and IPX8 at least 30 minutes at 1 meter; neither makes a light fit for diving.
• Impact rating: The height of a drop the light survived in six orientations; the Wedge, EDC29 and TINI 2 are rated for 1 m.
• Lockout: A lock mode, or a tail you can unscrew, keeps the light from switching on in a pocket or bag.
• Beam color: Some lights offer warm, neutral and cool white; Nitecore rates the warm 3000K mode of its EDC09 at CRI 97.

On the plane and on the trip

• Allowed in both bags: TSA allows flashlights in carry-on and checked bags; the officer at the checkpoint has the final say.
• Lithium inside the light: The FAA lets a rechargeable light go in a checked bag only if it is fully off and protected from accidental activation.
• Spare cells carry-on only: Spare lithium-ion cells, such as 18650s, must stay in the cabin, up to 100 Wh each, with terminals taped, bagged or in a case.
• AA and AAA cells: TSA allows alkaline and NiMH AA, AAA, C and D batteries in carry-on and checked bags, protected from damage.
• Lock it before packing: Fenix says to unscrew the tail a few turns or remove the battery so the light cannot switch on in transport.
• Charging on the road: USB-C lights charge from a phone charger or power bank; Fenix says its 21700 lights need a 2 A-plus charger, more than an iPhone charger gives.
• Heat or smoke: The FAA asks passengers to tell the crew at once if a battery-powered device overheats, swells, smokes or burns.

Limits and care

• Turbo is brief: The Wedge’s 1,000-lumen THRO mode lasts 35 seconds; the TINI 2’s 500-lumen turbo runs 15 minutes.
• They get hot: Outdoor Life found Nitecore’s EDC 25 uncomfortably hot to hold after 12 minutes at 1,000 lumens.
• Claims vary: Lumen figures are the maker’s; the bench site 1Lumen measured 3,253 lumens from the 3,000-lumen PD36R ACE.
• Protected cells only: Fenix bans unprotected lithium-ion cells in the PD36R ACE and warns that poor batteries can overheat or catch fire.
• Long storage: Fenix advises recharging a stored light every four months and removing the battery if it will sit unused for long.
• Clean contacts: Dirty battery contacts can make a light flicker or fail; Fenix recommends cleaning them from time to time.
• Flicker: Lights that dim by pulse-width modulation can show a visible flicker, most of all on moving objects.

A short history

The dry cell battery, invented in 1887 and mass-produced from 1896, made the flashlight possible. Its paste electrolyte did not spill and worked in any position.

• January 1899: British inventor David Misell receives U.S. Patent 617,592 for a D-battery light in a paper tube.
• 1904: The tungsten-filament lamp, three times as efficient as carbon, makes flashlights more useful and popular.
• 1999: Lumileds introduces the Luxeon high-power white LED; the Arc LS of 2001 is the first flashlight built around it.
• 2006: Maglite makes its first LED flashlight.
• 2009: ANSI publishes the FL1 standard for testing light output, beam, runtime, impact and water resistance.
• 2013: iOS 7 gives the iPhone a built-in flashlight that uses the camera flash.
• 2018: The first laser-excited phosphor (LEP) flashlight goes on sale.