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When all other lights go out, let one of these LED flashlights illuminate the darkness. Underhood Light
These are not your grandpa’s flashlights. LED (Light Emitting Diode) flashlights have largely replaced those with traditional light bulbs. Gone are the days of incandescent flashlights, with their dim amber glow, short battery life, and sensitivity to jolts, drops, and sudden bumps. LEDs in modern flashlights are brighter, more durable, and much more efficient than incandescent bulbs, which means batteries last longer. But, while most LED flashlights are improvements over their incandescent predecessors, some are better than others—so it’s important to select the right model for the job.
Traditional light bulbs are inefficient and waste a lot of energy. In fact, according to the U.S. Department of Energy, as much as 90 percent of the energy required to illuminate an incandescent light is given off—essentially lost—as heat. The introduction of halogen bulbs proved to be more efficient, although they can still generate a lot of heat. Aside from this, light-bulb filaments in flashlights are notoriously delicate, breaking when jolted or dropped.
LEDs, on the other hand, are 70 to 75 percent more efficient than incandescent lights. The LED itself is a semiconductor that emits light when current passes through it. Without a delicate filament suspended inside, the “emitter” is far more durable than a traditional light bulb. Because they’re more efficient, LEDs are brighter than incandescents using the same amount of power.
LEDs in flashlights, while more efficient than traditional bulbs, can still generate a fair amount of heat. And with some manufacturers vying to produce the brightest flashlight made, the heat generated can be significant. There are two ways to manage heat that may be employed independently or in conjunction with one another. The first is to physically draw off the heat by mounting the LED to a “heatsink,” a piece of metal, with a lot of surface area, that absorbs heat and allows it to dissipate. The second way is to regulate the power used to illuminate the LED. Too much heat can damage an LED, and it gets less efficient as it gets hotter. For this reason, many LED flashlights have circuitry to manage power consumption. This circuitry has another benefit too, as it prolongs battery life.
Flashlight brightness is measured in lumens, which is a measurement of “total light, radiating equally in all directions.” Manufacturers were historically optimistic in their published lumen figures, and while many are now reasonably accurate, there are still some dubious claims out there. Also note, manufacturers may list the highest possible lumen output of the LED in their light—although they may not be powering it to its full capability to reduce heat or prolong battery life. None of that really matters all that much though, because a light with a ton of lumens doesn’t necessarily mean it’s the brightest in practice—or the best light for you.
A super bright light may not cast a beam as far as a less bright light. Variables like the reflector shape and lens play a big role in how far the beam is thrown, and how wide it spreads. Also, consider that LEDs are brightest when they are first turned on. As they warm up, they slowly dim, which is usually imperceptible to our eyes. As the LED dims, our eyes adjust to the light and we can see better with less light.
IP is short for ingress protection, meaning protection from stuff getting inside the flashlight. Those letters will be followed by two numbers: The first digit relates to protection from solids like dust or grit. The second digit relates to protection from moisture, in this case the concern is usually water. Sometimes there will be an “X” in place of one of those numbers, which means the flashlight hasn’t been tested for protection from liquids or solids, depending on the position of the “X”.
For the first number, protection from solids, the highest number, six, indicates the light should be impenetrable by dust and sand. The highest value for the second number, representing protection from liquid, is eight—indicating that the flashlight can be submerged in water deeper than one meter, for longer than 30 minutes, with no harmful effects.
A flashlight’s IP rating gives a partial picture of its durability. You’ll also want to take into account things like the materials used—ranging from lightweight but less-than-durable plastic to rubberized enclosures to heavy-duty anodized aluminum—and whether the flashlight floats in water in addition to being waterproof, not to mention the warranty.
There are three main components of our flashlight testing: lumens, beam drop-off, and beam pattern. Lumen testing turned out to be a significant project that helped us gain insight to how lumens relate to flashlight performance. Lumens are measured using a device called an integrating sphere. Integrating spheres are hollow, with a white coating on the inside that diffuses light, bouncing it around in the sphere. A light is fixed in one port, pointing into the sphere, which collects all the light, allowing none to escape, so that it can be measured with a sensor in a second port.
Integrating spheres are lab-quality instruments and can be extremely expensive. However, once we understood how they work in theory, we built our own. In doing this, we consulted with product engineers at two companies to vet our ideas, verifying lumens on calibration lights in their sphere to make sure ours would be accurate. Once our sphere was calibrated, we measured each flashlight in our test at set intervals. We took measurements when we first turned the light on, then every 30 seconds up to 3 minutes; at 5 minutes, and then every 5 minutes up to 30 minutes. We used the measurement at 30 seconds as our official lumens figure for each light, because the brightness drops off quickly. After 30 seconds, most LEDs stabilize and dim at a much slower rate.
Beam drop-off is the point where the light is no longer bright enough to positively identify objects. We tested beam drop-off by placing 10 reflective traffic cones, in a line, every 5 meters out to 50 meters. We used a silhouette of a person, painted neutral gray, and moved it between the cones to determine the distance at which we could still identify it. The beam pattern we tested at 10 meters. We measured brightness in the center of the beam, then turned the light 5 degrees right and 5 degrees left and measured brightness at both points. This helped us determine the width of the bright, beam center.
Despite measuring 342 lumens in our integrating sphere, the 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.
Streamlight’s Polytac USB X was the top performer when it came to straight-up lumens. Starting at 554 lumens after 30 seconds, it dropped to 334 at 15 minutes and stayed relatively steady, ending 30 minutes at 324—100 lumens higher than any other light we tested. The fixed reflector projects a beam with a tight spot pattern that drops about 50 percent in brightness 5 degrees from the center on the left and right. At 50 meters, we could easily identify the crisp outline of our human silhouette, which was still clear out to about 90 meters.
We found the nylon polymer flashlight body plenty grippy, and it felt much less cold to the touch than aluminum in low temperatures. A two-way clip allows it to slip the Polytac inside or outside a pocket, oriented lens up or down—our preference was outside, lens down. There are three, preprogrammed function sets we were able to access using Streamlight’s Ten-Tap selector switch. The selection process is a little awkward, but most people will use it only once to set the preferred programs, which include low/medium/high, high/strobe/low, and high only. When we did the runtime test with the light set on high, the Polytac USB X ran for almost 5.5 hours before going dark. This is a good choice if you’re looking for a tactical flashlight with solid features and performance.
Ledlenser’s P5R is another great example of why you shouldn’t grade a flashlight solely on the lumen output. With its claimed lumens of 420, we were able to measure 393—not a big discrepancy. In practical testing, we discovered the P5R’s ability to focus the beam from a spot pattern to a flood pattern worked very well. Adjusting it to a tight spot, we were able to clearly identify a flat grey silhouette at 85 meters on a dark, moonless night—that’s as good or better than other lights with higher lumen output.
With three modes to choose from—low, high, and blink—we had no trouble switching between beam settings using the metal button on the end of the flashlight body. Rather than using a rubber-covered charge port, you use the magnetic charger to connect to the rear-mounted button, which serves as the charger contact.
Testing lumens in the integrating sphere, we discovered that brightness dropped about 30 lumens in the first 3 minutes. This kind of initial drop is common with LED lights, but after 3 minutes we noticed the brightness started to drop 1 lumen about every 4 seconds. We observed this until the brightness got down to 110 lumens. Stopping the test, we clicked the mode/power button and discovered we could get back to high power mode at about 300 lumens. So it appears, if left on, the light will eventually and slowly dim in order to preserve battery. In fact, when we tested runtime, we confirmed this. We couldn’t leave the light set to high for the duration. When we turned it on and left it, the battery died approaching 5 hours, a fair bit longer than the claimed run time of 3 hours on high power.
The Boulder LC 40 turned out to be a surprising value, with good runtime and a consistent 200-lumen output over time. Starting at just over 400 lumens when turned on, it dropped to 200 at about 3 minutes and didn’t stray more than 10 lumens for the remainder of our half-hour-long test. We found the beam pattern to be slightly narrower and more focused than the Polytac USB X above, which helped it throw nearly as far with fewer lumens. At 50 meters, we could clearly see the outline of our human silhouette, and it was still identifiable out to about 90 meters. The five light functions—high, medium, low, fast strobe, and slow strobe—are accessible with sequential clicks, about as simple a process as we found during testing. The aluminum body is completely sealed, so the battery can’t be replaced. But a port at the butt end of the light is provided to recharge it.
We measured a max lumen output of 1,536 for Fenix’s PD36R—very close to the advertised 1,600. And in our practical testing, the PD36R performed quite well. We ran to the limits of our test area when examining beam drop off. The beam projected is primarily an effective, focused spot, with a dimmer area surrounding it. We could easily identify our flat grey silhouette at 110 meters, reaching well beyond the reflective cones we had set out.
We found testing runtime to be a bit of a challenge. Like so many other LED flashlights, when set on their highest setting, the light dims if you leave it on for extended periods. There are typically two reasons for this: managing the heat created by the LED and preserving battery life. Regarding heat, we did experience the PD36R getting hot during use, with a maximum temperature at the bezel measured at 127 degrees. While this wasn’t where we would hold the flashlight, it still got to around 115 degrees near the mode button.
Unlike many other flashlights of this size and style, the PD36R has separate power and mode buttons, with power located in the tail cap and the mode button is just behind the bezel. When using the flashlight for longer periods, we preferred this arrangement, which allowed us to carry it low in our hand, with our thumb over the mode button. This differs from tactical lights with a single button in the tail cap, where we have to hold the light high, with our thumb over the tail and the bezel end near the heel of our hand. Over the course of our lumen test, we found the PD36R to be fairly stable. At 30 seconds, it measured 1,439 lumens. And at 20 minutes we measured 1,171 lumens, a drop of 18 percent.
As a tactical flashlight, the LED CR123 is designed to be gripped with fingers around the body and the thumb wrapped over the tail cap and the “quick-click” power button. You use this button to access light functions, of which there are three: momentary, full power, and power-saving. We found the button operation similar to most tactical flashlights, where you click and hold the button to keep the light on, and release it to turn off. Clicking twice, we reached full power, and three times brought us to power-saving mode. Clicking once from any mode turns the light off.
When we tested total light output at full power over 30 minutes, the Mag-Tac CR123 peaked at 258 lumens after 1 minute. We noted a gradual drop off, logging 184 lumens at the 5-minute mark. Then the output nearly flattened, gradually dipping to 154 lumens at the end of the half hour. Using our neutral, grey silhouette as a target, we could identify it on a cloudless night at 70 meters and barely pick it out at 75 meters—but not clearly enough to discern the outline. The beam itself is fairly narrow and projects like a spotlight.
We measured run time, at full power, at just over 5 hours and 47 minutes. Using power-saving mode exclusively, we extended the battery life by about 65 percent (13 hours). The Mag-Tac CR123 comes with replaceable, CR123 lithium batteries. These maintain high levels of energy and deliver it in powerful surges—even after extended periods of disuse—so, they’re a good choice for LED flashlights kept for emergencies or that you use infrequently.
The small Tac 300 from Energizer is one of only two lights that tested over the manufacturer’s claimed lumens. We recorded 325 lumens after 30 seconds, dropping to 300 after 10 minutes. Beyond the 10-minute mark in our test, the Tac 300 steadily dimmed until it went out at a little over 8 hours. For such a small light, it impressed us with how far the beam carried when we tested for beam drop-off. Identifying our human silhouette at 25 meters was very easy. Moving out to 50 meters we could still make it out, and pushing out to about 90 meters, we could still see it, although it was getting difficult to ID.
The aluminum flashlight body features three knurled areas to help maintain your grip on it and a pocket clip that you can move to either end to orient the lens up or down. The Tac 300 has three basic light functions—high, low, and strobe—that can be accessed by sequentially clicking the button on the butt of the light. Runtime is over 8 hours, although beyond 18 minutes that will be at less than 200 lumens. The Tac 300 is an inexpensive, basic flashlight that will serve you best in situations that require short bursts of use.
This medium-size Rayovac, powered by three alkaline AAA batteries, ran for a hard-to-believe two-plus days in our testing. We measured lumens at 271, 30 seconds after we turned it on—that’s 21 more than the manufacturer claims. Brightness dropped off gradually over our 30-minute test, ending at 165 lumens. In the second day of the runtime test, the light had dimmed very significantly but still gave off enough light by which to read in the dark, when held inches from a page. The light color is a little more amber than the others tested, which we found more evident in the last half of its runtime. Testing beam drop-off, we found it bright enough at 50 meters to identify our human silhouette. Moving out to the end of our test area at about 90 meters, we were still able see the silhouette, just not as clearly.
Waterproof Hand Lamp The DIY3AAA has two modes—high and energy saver—which can be toggled between by clicking the power button on the butt end of the light. The housing features rubber coverings on both ends to help protect it from drops and also prevent the otherwise smooth body from slipping out of our hands.