Flashlights, like electricity, transformed our capabilities, illuminating the world and making things like camping and travel so much more accessible and easy. The tool has a unique and interesting history, and has evolved over time. Join me in discovering the history, and how flashlights actually work.
The History of Flashlights
The first dry cell battery was invented in 1887. Unlike previous batteries, it used a paste electrolyte instead of a liquid. This was the first battery suitable for portable electrical devices, as it did not spill or break easily and worked in any orientation. The first mass-produced dry cell batteries came in 1896, and the invention of portable electric lights soon followed. Portable hand-held electric lights offered advantages in convenience and safety over (combustion) torches, candles and lanterns. The electric lamp was odorless, smokeless, and emitted less heat than combustion-powered lighting. It could be instantly turned on and off, and avoided fire risk.
In 1888, a Russian immigrant and inventor named Conrad Hubert founded the American Electrical Novelty and Manufacturing Company (later renamed Eveready). Hubert’s company manufactured and marketed battery-powered novelties. For example, neckties and flower pots that lit up. Batteries were still a novelty at that time, then only recently introduced to the consumer market.Why was the flashlight called a flashlight? The first flashlights used batteries that did not last very long. They provided a “flash” of light, so to speak. However, Conrad Hubert continued to improve his product and made the flashlight a commercial success. It helped make Hubert a multi-millionaire, and Eveready a huge company. With Misell’s help, Hubert developed the first tubular flashlight, and collected testimonials by handing out early versions to policemen in New York City. Soon several other companies introduced similar devices. Taking advantage of improved batteries and more efficient tungsten bulb filaments, Eveready released flashlights with on/off switches in 1911.
On January 10, 1899, British inventor David Misell obtained U.S. Patent No. 617,592, assigned to American Electrical Novelty and Manufacturing Company. This “electric device” designed by Misell was powered by “D” batteries laid front to back in a paper tube with the light bulb and a rough brass reflector at the end. The company donated some of these devices to the New York City police, who responded favorably to them.
Carbon-filament bulbs and fairly crude dry cells made early flashlights an expensive novelty, with low sales and low manufacturer interest. Development of the tungsten-filament lamp in 1904, with three times the efficacy of carbon filament types, and improved batteries, made flashlights more useful and popular. The advantage of instant control, and the absence of flame, meant that hand-held electric lights began to replace combustion-based lamps such as the hurricane lantern. By 1922 several types were available; the tubular hand-held variety, a lantern style that could be set down for extended use, pocket-size lamps for close work, and large reflector searchlight-type lamps for lighting distant objects. In 1922 there were an estimated 10 million flashlight users in the United States, with annual sales of renewal batteries and flashlights at $20 million, comparable to sales of many line-operated electrical appliances. Flashlights became very popular in China; by the end of the 1930s, 60 companies made flashlights, some selling for as little as one-third the cost of equivalent imported models. Miniature lamps developed for flashlight and automotive uses became an important sector of the incandescent lamp manufacturing business. LED flashlights were made in the early 2000s. Maglite made their first LED flashlight in 2006.
Different Types of Flashlights
Incandescent flashlights use incandescent light bulbs, which consists of a glass bulb and a tungsten filament. The bulbs are under vacuum or filled with argon, krypton, or xenon. Some high-power incandescent flashlights use a halogen lamp where the bulb contains a halogen gas such as iodine or bromine to improve the life and efficacy of the bulb. In all but disposable or novelty flashlights, the bulb is user-replaceable; the bulb life may be only a few hours.
The light output of an incandescent lamp in a flashlight varies widely depending on the type of lamp. A miniature keychain lamp produces one or two lumens. A two-D-cell flashlight using a common prefocus-style miniature lamp produces on the order of 15 to 20 lumens of light and a beam of about 200 candlepower. One popular make of rechargeable focusing flashlight uses a halogen lamp and produces 218 lumens. By comparison, a 60-watt household incandescent lamp will produce about 900 lumens. The luminous efficacy or lumens produced per watt of input of flashlight bulbs varies over the approximate range of 8 to 22 lumens/watt, depending on the size of the bulb and the fill gas, with halogen-filled 12-volt lamps having the highest efficiency.
Powerful white-light-emitting diodes (LEDs) have mostly replaced incandescent bulbs in practical flashlights. LEDs existed for decades, mainly as low-power indicator lights. In 1999, Lumileds Corporation of San Jose, California, introduced the Luxeon LED, a high-power white-light emitter. This made possible LED flashlights with power and running time better than incandescent lights. The first Luxeon LED flashlight was the Arc LS, designed in 2001. White LEDs in 5 mm diameter packages produce only a few lumens each; many units may be grouped together to provide additional light. Higher-power LEDs, drawing more than 100 milliamperes each, simplify the optical design problem of producing a powerful and tightly controlled beam.
LEDs can be significantly more efficient than incandescent lamps, with white LEDs producing on the order of 100 lumens for every watt, compared to 8-10 lumens per watt of small incandescent bulbs. An LED flashlight has a longer battery life than an incandescent flashlight with comparable output. LEDs are also less fragile than glass lamps. LED lamps have different spectra of light compared to incandescent sources, and are made in several ranges of color temperature and color rendering index. Since the LED has a long life compared to the usual life of a flashlight, very often it is permanently installed. Flashlights made for an incandescent lamp can often be upgraded to a more efficient LED lamp.
LEDs generally must have some kind of control to limit current through the diode. Flashlights using one or two disposable 1.5-volt cells require a boost converter to provide the higher voltage required by a white LED, which needs around 3.4 volts to function. Flashlights using three or more dry cells may only use a resistor to limit current. Some flashlights electronically regulate the current through the LEDs to stabilize light output as the batteries discharge. LEDs maintain nearly constant color temperature regardless of input voltage or current, while the color temperature of an incandescent bulb rapidly declines as the battery discharges, becoming redder and less visible. Regulated LED flashlights may also have user-selectable levels of output appropriate to a task, for example, low light for reading a map and high output for checking a road sign. This would be difficult to do with a single incandescent bulb since efficacy of the lamp drops rapidly at low output.
LED flashlights may consume 1 watt or much more from the battery, producing heat as well as light. In contrast to tungsten filaments, which must be hot to produce light, both the light output and the life of an LED decrease with temperature. Heat dissipation for the LED often dictates that small, high-power LED flashlights have aluminium or other high heat-conductivity bodies, reflectors, and other parts to dissipate heat; they can become warm during use. Light output from LED flashlights varies even more widely than for incandescent lights. “Keychain” type lamps operating on button batteries, or lights using a single 5 mm LED, may only produce a few lumens. Even a small LED flashlight operating on an AA cell, but equipped with an LED, can emit 100 lumens. The most powerful LED flashlights produce more than 100,000 lumens and may use multiple LEDs.
LEDs are highly efficient at producing colored light compared with incandescent lamps and filters. An LED flashlight may contain different LEDs for white and colored light, selectable by the user for different purposes. Colored LED flashlights are used for signalling, special inspection tasks, forensic examination, or to track the blood trail of wounded game animals. A flashlight may have a red LED intended to preserve dark adaptation of vision. Ultraviolet LEDs may be used for inspection lights, for example, detecting fluorescent dyes added to air conditioning systems to detect leakage, examining paper currency, or checking UV-fluorescing marks on laundry or event ticket holders. Infrared LEDs can be used for illuminators for night-vision systems. LED flashlights may be specified to be compatible with night vision devices.
A less common type of flashlight uses a high-intensity discharge lamp (HID lamp) as the light source. An HID gas discharge lamp uses a mixture of metal halide salts and argon as a filler. HID lamps produce more light than an incandescent flashlight using the same amount of electricity. The lamp lasts longer and is more shock resistant than a regular incandescent bulb, since it lacks the relatively fragile electrical filament found in incandescent bulbs. However, they are much more expensive, due to the ballast circuit required to start and operate the lamp. An HID lamp requires a short warm-up time before it reaches full output.
What Powers a Flashlight?
This is the most common way a flashlight is powered, and probably the form you’re most familiar with. In fact, I don’t think I’ve ever encountered a flashlight powered by anything else – they do exist, however. Primary battery (disposable) types used in flashlights include button cells, carbon-zinc batteries in both regular and heavy duty types, alkaline, and lithium.
Secondary, rechargeable types include lead-acid batteries, NiMH, NiCd batteries and lithium ion batteries. The choice of batteries plays a determining role in the size, weight, run time, and shape of the flashlight. Flashlight users may prefer a common battery type to simplify replacement. Primary cells are most economical for infrequent use. Some types of lithium primary cell can be stored for years with less risk of leakage compared with zinc-type batteries. Long storage life is useful where flashlights are required only in emergencies. Lithium primary batteries are also useful at lower temperatures than zinc batteries, all of which have water-based electrolytes. Lithium primary batteries have a lower internal resistance than zinc primary batteries, so are more efficient in high-drain flashlights.
Flashlights used for extended periods every day may be more economically operated on rechargeable (secondary) batteries. Flashlights designed for rechargeable batteries may allow charging without removing the batteries; for example, a light kept in a vehicle may be trickle-charged and always ready when needed. Some rechargeable flashlights have indicators for the state of charge of the battery. Power-failure lights are designed to keep their batteries charged from a wall plug and to automatically turn on after an AC power failure; the power-failure light can be removed from the wall socket and used as a portable flashlight. Solar powered flashlights use energy from solar cells to charge an on-board battery for later use.
2. Mechanical Power
One type of mechanically powered flashlight has a winding crank and spring connected to a small electrical generator (dynamo). Some types use the dynamo to charge a capacitor or battery, while others only light while the dynamo is moving. Others generate electricity using electromagnetic induction. They use a strong permanent magnet that can freely slide up and down a tube, passing through a coil of wire as it does. Shaking the flashlight charges a capacitor or a rechargeable battery that supplies current to a light source. Such flashlights can be useful during an emergency, when utility power and batteries may not be available. Dynamo-powered flashlights were popular during the Second World War since replacement batteries were difficult to find.
At least one manufacturer makes a rechargeable flashlight that uses a supercapacitor to store energy. The capacitor can be recharged more rapidly than a battery and can be recharged many times without loss of capacity; however, the running time is limited by the relative bulk of capacitors compared to electrochemical batteries.
How does the light Reflect outwards?
A reflector with an approximately parabolic shape concentrates the light emitted by the bulb into a directed beam. Some flashlights allow the user to adjust the relative position of the lamp and reflector, giving a variable-focus effect from a wide floodlight to a narrow beam. Reflectors may be made of polished metal, glass, or plastic with an aluminized reflective finish. Some manufacturers use a pebbled or “orange peel”, instead of a smooth reflector, to improve the uniformity of the light beam emitted. Where multiple LEDs are used, each one may be put in its own parabolic reflector. Flashlights using a “total internal reflection” assembly have a transparent optical element (light pipe) to guide light from the source into a beam; no reflector surface is required. For a given size of light source, a larger reflector or lens allows a tighter beam to be produced, while capturing the same fraction of the emitted light. Some flashlights use Fresnel lenses, which allow the weight of the lens to be reduced.
The reflector may have a flat transparent cover to keep out dirt and moisture, but some designs have a plastic or glass “bulls-eye” lens to form a concentrated beam. The lens or reflector cover must resist impacts and the heat of the lamp, and must not lose too much of the transmitted light to reflection or absorption. Very small flashlights may not have a reflector or lens separate from the lamp. Some types of penlight bulbs or small LEDs have a built-in lens.
A reflector forms a narrow beam called the “throw” in hobbyist parlance, while light emitted forward misses the reflector and forms a wide flood or “spill” of light. Because LEDs emit most light in a hemisphere, lens lights with the LED facing forward or reflector lights with it facing backwards radiate less spill. Variable focus “zoom” or “flood to throw” lights may move the reflector or lens or they may move the emitter; moving the emitter presents the designer with the problem of maintaining heat dissipation for the LED.
What are Flashlights Made of?
Early flashlights used vulcanized fiber or hard rubber tubes with metal end caps. Many other materials including drawn steel, plated brass, copper, or silver, and even wood and leather have been used. Modern flashlights are generally made of plastic or aluminum. Plastics range from low-cost polystyrene and polyethylene to more complex mixtures of ABS or glass-reinforced epoxies. Some manufacturers have proprietary plastic formulations for their products. A desirable plastic for manufacturing flashlights allows for ease of molding and adequate mechanical properties of the finished flashlight case. Aluminum, either plain, painted or anodized, is a popular choice. It is electrically conductive, can be easily machined, and dissipates heat well. Several standard alloys of aluminum are used. Other metals include copper, stainless steel, and titanium, which can be polished to provide a decorative finish. Zinc can be die-cast into intricate shapes. Magnesium and its alloys provide strength and heat dissipation similar to aluminum with less weight, but they corrode easily.
Metals may be drawn into a tubular shape, or tubular extruded stock can be machined to add threads for the head and tail cap, knurling for grip, and decorative and functional flats or holes in the body. LED flashlights may have cooling fins machined into their metal cases. Plastics are often injection molded into nearly final shape, requiring only a few more process steps to complete assembly. Metal cases provide better heat dissipation for the LED, but plastics are not electrically conductive and may resist corrosion and wear.
The Top 10 Flashlights on the Market
1.ThruNute Archer 2A V3
The ThruNite Archer 2A V3 has the widest range of brightness settings of any AA-battery-powered light we tested, including a very dim mode that allowed us to read a map (without destroying our night vision) and a bright setting that illuminated trees 500 feet away. Like many of the best flashlights, this light has a two-button interface that lets you easily toggle through the brightness levels one-handed. The blinding strobe mode is useful in an emergency—but the Archer 2A V3’s design makes it easy to avoid activating the strobe during regular use, an advantage over most competitors. The Archer 2A V3 also boasts a number of other features found on more-expensive lights: It doesn’t roll on a flat surface, it stands upright on its rear end, it can survive a 1-meter drop or full immersion in water—try that, smartphones—and it has a memory function as well as a momentary-on feature that turns the light on and off with a half-press of the rear button. Its two-AA-powered beam pattern produces such good overall visibility that, even after trying all the other lights, we reached for this flashlight first when we headed into the woods.
2. Olight S2R Baton II
The Anker LC130 offers a powerful 1300 lumens for hunting or home security situations and high, medium, low, strobe, and SOS mode. I’s 1,200-foot range is powerful enough to light up two football fields. Our tester appreciated the flashlight’s easy controls and setup, as well as its durable feel. The rugged, waterproof flashlight can withstand drops from at least 1 meter and will work even after submersion in water for 30 minutes.
When fully charged, it has a battery life of six hours. When it’s time to recharge, you have to unscrew the tail cap to access the USB port. While this may seem like a hassle, it’s necessary to keep the flashlight water-resistant. Even with an aluminum body, it weighs in at over 1 pound. If you’re looking for a flashlight for leisurely night walks or retrieving something from basement storage, you may want to opt for something lighter.
If you enjoy outdoor activities and want a compact, rugged flashlight to carry, you might want to consider the Fenix E12 V2.0 flashlight. Like most of the selections from Fenix, this model is IP68 rated, which means it’s dustproof and able to handle submersion in up to 1 meter of water for 30 minutes. This ultra-light flashlight takes a single AA battery and produces 160 lumens on High, 30 lumens on Medium, and 5 lumens on Low mode.
In addition to the light, durable build, the aircraft-grade aluminum body has a knurled finish so it won’t slip from your grip, and the built-in overheat protection prevents it from getting hot to the touch. It’s a mini flashlight, however, so it will not provide you with the same lighting power as a full-sized option. Also, keep in mind that the light defaults to the lowest brightness setting upon turning it on. However, its compact size, lightweight design, and adjustable pocket clip make it easy to take with you anywhere.
At just a little over an ounce and a couple of inches long, you’ll barely notice that you have this Thorfire Cap Hat Light clipped to your cap, jacket, or waistband. The five 30-lumen LED lights brightly illuminate your immediate area, making it ideal for campers, fishers, or runners who want to light their path without disturbing their surroundings, and it won’t fully blind you should you look right at it.
The uniform beam doesn’t flicker and won’t distort colors. You can rotate the head 90 degrees to be horizontal or vertical. The light runs on two CR2032 button batteries and gives up to 4 hours of working time. Unfortunately, the on/off button, located on the clip, can be difficult to find at first. It’s also very small, and it won’t produce the level of bright light you may desire for heavier-duty, rugged outdoor tasks.
If you’re interested in a tough tactical flashlight for outdoor or other uses, the OLIGHT Warrior X Pro Superior Tactical Thrower combines ruggedness with several impressive features. This IPX8 waterproof and drop-proof (up to 3 meters) device features a durable aluminum alloy construction with details like a knurling pattern to provide slip-free grip. It offers a maximum brightness of 2100 lumens on High, though the runtime is capped at two minutes on this mode. Low mode lasts longer at around eight hours and produces 300 lumens.
Choosing between lighting modes is easy, thanks to the responsive tactical tail switch, and so is staying aware of the battery life. A flashing indicator illuminates rapidly to let you know when the internal rechargeable battery needs a jolt. Another plus is that the provided charging cable is magnetic and offers easy placement at the base of the device. While all of this functionality and ruggedness comes at a more premium cost and heavier overall weight than alternatives, this could be a high-performing flashlight to keep in your emergency bag.
The Outlite S1000 Portable Handheld LED Flashlight offers bright light and flexible control over its intensity and flow. It’s compact and lightweight but robust enough to handle the rugged outdoors, thanks to its aluminum alloy casing, water-resistant design, and ability to withstand 10-foot drops.
The flashlight has five different light modes: High, Medium, Low, Strobe, and SOS. The Strobe mode will flash the light faster, while the SOS mode will flash at a slower pace. While the lumen output is lower than other models, you also can zoom in and focus your light, which will produce a narrow spotlight that can stretch out up to 656 feet (200 meters). You can also zoom out and widely spread your light over a greater surface area. The S1000 is your model if you’re looking for a durable, budget-friendly, and feature-packed flashlight for your next outdoor adventure. However, it would be wise to keep a spare set of batteries for longer excursions since users note that the battery can deplete quickly.
The OLIGHT Seeker 3 Pro Flashlight packs powerful brightness into a durable, rechargeable, and feature-packed design. This flashlight is drop- and waterproof and produces a light beam that extends up to 250 feet outward. The brightness is easily adjustable via the handy rotary knob, which allows you to switch between the five different brightness modes, with 5 lumens being the lowest brightness option and a whopping 4200 lumens being the highest. It also relies on sensors to automatically lower the light’s brightness if the lens becomes blocked or the flashlight begins to overheat and locks on its own after 30 seconds.
Monitoring your flashlight is a breeze, thanks to the brightness level and battery life gauges on the rotary knob. You can expect up to 15 days of use before needing to recharge this flashlight via the included USB magnetic cable. You may find this flashlight’s brightness and additional functions to be more than you need. However, the Seeker 3 Pro is ideal if you want a user-friendly, rugged model with a lot of built-in features.
7. Manker E12
If the ThruNite Archer 2A V3 is not available, we also like the Manker E12. This light is very similar to the Archer 2A V3, down to the two-button interface and the four brightness levels. It also shares the nice wide-angle beam, the momentary-on function, the memory feature, the anti-roll body design, and the full waterproof rating. The only significant difference is that the E12’s lowest setting is brighter than the Archer 2A V3’s, and we really preferred our pick’s ability to go very dim. Plus, the Manker usually costs a few dollars more than our pick.
8. ThruNite TC15 V3
We have also looked at rechargeable flashlights, and not surprisingly, the ThruNite TC15 V3 USB rechargeable flashlight hits the same balance as the Archer 2A V3, offering high-end features at an entry-level price. The TC15 V3 is just barely bigger than the Archer 2A V3, but at the high setting it’s twice as bright with a similar run time. It has a one-button interface that allows for instant access to both the brightest and dimmest settings. The included USB charging cord plugs directly into the flashlight, unlike on the majority of rechargeable flashlights, where you have to remove the 18650 battery for charging. The TC15 V3 typically costs between $50 and $60, at the lower end of rechargeable lights.
The downsides of the TC15 V3 are universal across rechargeable flashlights. First, once the battery is drained, it takes time to fully charge again (in this case roughly three hours), so bringing a rechargeable flashlight back to life isn’t as quick as simply swapping out AA batteries. Also, if the battery drains during a power outage, you can’t use the light anymore unless you have an independent power source to recharge (or additional 18650 batteries). Rechargeable lights are great and offer a lot of convenience, but for the above reasons, we still prefer AA-battery-powered flashlights for our main recommendation. This latest version of the TC15, the V3 model, has an improved pocket clip and replaces the original TC15 as our also-great pick.
The Olight I3T EOS 180 is a compact and portable flashlight ideal for everyday carrying. Its 3.5-inch long and 1.4-ounce build is light and slim, and the rotating, dual-direction pocket clip makes toting this flashlight easy. The double helix body knurling also offers solid grip control,
It’s effective and efficient, too. It requires only one AAA battery and has two different brightness modes, with the lowest brightness at 5 lumens and the highest brightness jumping up to 180 lumens. On High mode, the battery lasts only 21 minutes. However, the battery will last for 16 hours while operating on Low mode. Fortunately, for everyday use, the low mode should be sufficient. While other flashlights offer additional lighting modes and longer battery life, it’s hard to beat the portability of the Olight I3T.
10. Maglite ML50L
Despite measuring 342 lumens in our integrating sphere, the Maglite’s ML50L performed on par with brighter lights in practical testing. In beam drop-off testing, at a measured distance of 50 meters and using a focused spot pattern, we found our human silhouette was brightly illuminated and easy to identify. Pushing out beyond that to about 90 meters, we could still ID the silhouette. With the reflector adjusted in a flood pattern, the silhouette was identifiable at 50 meters, with a much wider area illuminated, but not as bright as the spot focus. With the reflector pulled back in floodlight orientation, we noted a dim zone in the center of the beam. The ML50L has five functions—high, low, eco, strobe, and momentary on—that are arranged in four function sets with three functions each. The general and outdoor function sets each feature high and low functions, with general including eco, and outdoor including strobe. Law enforcement and tactical function sets both feature momentary on, where the light comes on when the switch is pressed and turns off when released. They both include the high setting, while law enforcement also has eco, and tactical has strobe. We found setting the desired function set to be relatively easy and will be something most people would do only once. Switching between functions simply required a single, double, or triple click. The ML50L is a good example of why the most lumens don’t always make the best flashlight. The focusing reflector helps this flashlight throw a beam as far as technically brighter lights, as well as making it a little more versatile.