Please review the following frequently asked questions, the User's Guide for each product and the product comparison chart. If you have a question after reviewing this material, please contact us by e-mail or phone.
LED stands for light emitting diode. LEDs are classified as solid state devices and can withstand tremendous shock and vibration. High quality LEDs will last a lifetime when built into properly designed equipment. Let's compare LEDs to other types of lighting devices.
The common incandescent light works by passing a current through a fine wire - the filament. The current passing through the filament heats the wire to incandescent temperatures - 2800 to 3200°K. That is, the wire is so hot it glows. The incandescent light typically looks yellow-orange compared to noon day sunlight. The filament is relatively delicate at incandescent temperatures and can break if exposed to significant shock. or vibrations. Further, the filament slowly evaporates at those high temperatures, causing the filament to fail. Low wattage flashlight bulbs typically fail in under 15 hours and often fail just as the light is turned on. Finally, the incandescent light is relatively inefficient with typical efficiencies in the 15 to 22 lumens per watt range.
The common fluorescent light and metal halide light are examples of arc lights. They work by passing a current through a gas enclosed in a glass tube. In the case of the fluorescent light, the gas contains mercury vapors and the interior of the glass tube is coated with phosphors to convert the UV light given off by the mercury to white light. These lights can generate light that looks very close to noon day sunlight. The glass tube is relatively delicate and can break if exposed to a significant shock. However, these lights are relatively efficient with typical efficiencies exceeding 60 lumens per watt.
The LED is a solid state device similar to a transistor. It is a solid block of material that is attached to the case. The current is passed though the material in the forward direction to make the material emit light. Although small bonding wires are often used to route current to the material, they are encapsulated in a clear material that re-enforces them and makes them very strong. The result is a rugged device that can withstand significant shock and vibration without damage. The latest LEDs are now exceeding 160 lumens per watt at medium power levels (early 2014) and can be expected to increase in efficiency by roughly 10% each year for the next many years.
Almost all of today's white LEDs work by combining blue light with yellow phosphors to generate white light. The die of the LED generates a blue light and when the blue light hits the yellow phosphor, the blue light is converted into green, yellow and red light. This can give rise to different tints of white and allow for special LEDs with a high color rendering index (CRI).
The Lumen is the international unit of luminous flux, which is a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power (radiant flux) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux measurements indicate the total power of all electromagnetic waves emitted, independent of the eye's ability to perceive it.
Your eyes are not uniformly sensitive to all colors of light. Your eyes are most sensitive to green light and least sensitive to violet and red light. The lumen takes the relative sensitivity of your eyes into consideration. The spectral content of light is multiplied by the sensitivity curve of your eye to create a final result. Thus, a milliwatt of green light (555nm) counts much higher in lumens than a milliwatt of violet light (415nm) or a milliwatt of red light (630nm).
The lumen is interrelated with two other units of light measurement: lux and candela. A lux is the measure of illuminance, which means how much light is falling on a surface. The candela is the measure of luminous intensity, which means how much light is being emitted in a particular direction. These units of measure have the following relationships. A lux is one lumen spread over one square meter. A candela is one lumen spread across the solid angle of one steradian. The area at one meter distance from the point of a cone that occupies one steradian is one square meter. Thus one lumen is equal to one lux which is equal to one candela for one steradian at one meter from the source.
LEDs are tested after manufacture and sorted into bins. One of the bin categories has to do with how many lumens the LED will generate under a well defined set of conditions. For example, one manufacture places LEDs that generate from 87.4 lumens to 113.6 lumens at 350mA into their U bin and LEDs that generate from 113.6 lumens to 147.7 lumens into their V bin. The manufacturer allows a production tolerance of +/-10% for the measuring equipment. This means that the output of LEDs within one bin can vary over a 40% range.
It is common for a flashlight manufacturer to improve their flashlight's apparent output specification by claiming that they are generating the average bin lumens stated on the LED manufacturer's specification sheet. Or they may state the output specification as "up to" the maximum bin lumens stated on the LED manufacturer's specification sheet. Both of these are deceptive practices. This is referred to as spec sheet lumens.
An example will help you understand the deception of spec sheet lumens. Suppose we have an LED from a bin with a typical 40% spread - 180 lumens to 300 lumens. The average will be 240 lumens. The "up to" will be 300 lumens. And that is before we have taken losses from the optical system into consideration. In the end, you can end up with a 200 lumen flashlight being marketed as a 300 lumen flashlight. But wait, the deception gets worse.
The LED's spec sheet lumens are typically measured under ideal conditions at 25°C - before the LED has a chance to heat up. Once the LED operates at full power for a short period it will heat up and loose at least 20% of it's lumen output. So if the LED was from the bottom of the bin, you may find the LED is generating less than 50% of the claimed lumens under real conditions. The "up to" 300 lumens flashlight may only be generating 150 lumens - at the LED. Once you take the optical system losses into account, you may be getting 35 to 45% of the claimed lumens out the front of the flashlight.
A better way to rate flashlights is to measure the light output after it has passed through the optical system and once the LED has had a chance to warm up. This is sometimes referred to as out-the-front (OTF) lumens. This is the method prescribed by the ANSI FL-1 standard. Unfortunately, the ANSI FL-1 standard allow you to perform the testing on 3 "representative" lights, which does not take care of the unit-to-unit variations between individual LEDs within the same bin. Two flashlights with the same lumen rating can still produce easily visible differences in output.
HDS Systems is the only manufacturer to go the final step and calibrate each flashlight. We measure the output of each flashlight after it is completely assembled and adjust the output to produce the specified lumen output. This method allows the LED to warm up to operating temperature as part of the measurement process so the flashlight's true lumen output can be measured and adjusted under representative operating conditions. Thus, our 250 lumen flashlight can be counted on to actually produce 250 lumens.
ANSI is the American National Standards Institute and NEMA is the National Electrical Manufacturers Association. The ANSI/NEMA FL-1 standard is a basic performance measurement standard for flashlights. The standard specifies how testing should be performed and how results should be reported. HDS Systems uses the ANSI/NEMA FL-1 standard when measuring corresponding flashlight specifications.
Light output is measured using an integrating sphere with a spectral radiometer and is reported in lumens. Light output is measured 30 seconds after the flashlight is turned on to allow the LED to warm up.
Peak beam intensity is calculated from the measured illumination level at a specified distance and is reported in candela. Light output is measured 30 seconds after the flashlight is turned on to allow the LED to warm up.
Beam distance is calculated from the measured illumination at a specified distance and is reported in meters. The distance is the point at which the illumination level becomes 0.25 lux. Light output is measured 30 seconds after the flashlight is turned on to allow the LED to warm up.
Runtime is the time it takes the flashlight's output drops to 10% of the starting light output and is reported in minutes (<1 hour), hours and 15 minutes intervals (1 to 10 hours) or hours (> 10 hours). Standard rounding applies. The starting light output is measured 30 seconds after the flashlight is turned on to allow the LED to warm up.
Impact resistance is tested by dropping the flashlight on all 6 cubic orientations from the claimed height in whole meters. To pass, there must be no visible cracks or breaks and the flashlight must remain fully functional.
The water submersion rating is tested by submerging the flashlight to the claimed depth pressure for 4 hours. To pass, no water may enter the flashlight and the flashlight must be fully functional following the test.
The ANSI FL-1 standard defines beam distance as the distance at which the beam will illuminate a surface to 0.25 lux, which is equivalent to the amount of light from a full moon. The Inverse Square Law can be used to calculate corresponding distances for other levels of surface illumination.
The actual distance you can see not only depends on the levels of surface illumination, it also depends on how dark adapted your eyes are. If your eyes are adapted to a brightly lit scene, you will not even be able to see a surface illuminated to 0.25 lumens. If it was possible to know what your level of dark adaptation was, you could - in theory - use the inverse square law to find the distance that would result in a sufficiently high surface illumination for you to see an object.
The lumen-minute is a convenient concept for rating the efficiency of a flashlight. If you graph the output of a flashlight against time and calculate the area under the curve you can calculate the number of lumen-minutes produced by a flashlight for the period. The more lumen-minutes, the more light was generated by the flashlight and the more efficiently the light was generated.
When comparing two different flashlights there are two things to keep in mind. First, your eyes are logarithmic. That means that an increase in light output of 25% or a decrease of 20% is barely distinguishable and can safely be ignored. There needs to be a fairly large difference in output to make any operational difference when using a flashlight. Second, minutes of operation tend to be more valuable than absolute light output. Remember, your eyes will rapidly adapt to the existing light output and any visually small difference in light output will be muted by the adaptation.
In general, higher power settings are less efficient than lower power settings, with the efficiency dropping rapidly as you approach the maximum design limits for the LED, power supply and battery. At the maximum design limits you trade off a large percentage of your runtime for an almost imperceptible increase in brightness. This is because your eyes are logarithmic and the LED, electronics and battery performance are dropping at an N-squared rate. It is a loser's game to maximize output at any cost. Comparing the lumen-minutes will quickly show the folly.
Today's white LEDs generate white light by shining a blue light through a "yellow" phosphor. The blue and "yellow" combine to make white. We say "yellow" because the phosphor has a wide spectral emission that goes from green to red and thus appears to be emitting a yellowish light. The resulting shade of white - or tint - can vary significantly because of variations in the type of phosphor, the purity of the phosphor, the thickness of the phosphor layer and the spectral content of the blue light emitted from the die.
Achieving a consistent white color is very difficult to do with current LED technology and so each LED has a slightly different tint. From an aesthetics point of view, this can be annoying. If you compare two lights side by side they are likely to have two different tints - which always leads to the question of: which LED has the better tint? From a practical point of view, if both lights are used separately, each will work equally well and you may never notice that one or the other has a tint. From a personal point of view, everyone has a personal preference.
The color white encompasses a wide range of unsaturated colors and thus the color white can take on the tint of any color of the rainbow. We perceive a color to be white when it contains a sufficiently balanced mixture of colors to stimulate the three color receptors in your eyes. This can be done with only two colors but additional colors provide a much greater range of acceptable results and better color rendering.
If you take an object and heat it to incandescence, that object radiates a certain spectrum of light; That spectrum closely approximates the spectral emissions of a theoretical black body radiator heated to the same temperature. A black body is an object which absorbs all incident light and thus is black in appearance at room temperature. As you raise the temperature of the black body radiator, the incandescent color shifts from infrared to red to the blue-purple part of the spectrum along a curved line which is typically plotted on the CIE-1931 Chromaticity Diagram. This line is known as the Planckian black body radiator line.; "White" is generally considered to start at 2500°K
The best white colors lie along the Planckian black body radiator line in the range of 4000°K to 7000°K with typical noon daylight being in the range of 5500°K to 6500°K depending on how much northern sky light is included. Incandescent lights generally lie in the range of 2800°K to 3200°K and have a distinct orange cast when compared to daylight. The definition of white is the equal energy point that lies at x=0.333 y=0.333 on the CIE-1931 Chromaticity Diagram and corresponds to 5454°K.
The human visual system is very good at color-correcting the scene you are looking at to accommodate different "white" lights. As long as there is sufficient color information available, a white surface will take on a white appearance within a short time, even if the "white" light is far from the Planckian black body radiator line or far from daylight.
LEDs are available in a wide range of tint. The highest efficiency is achieve with the cool white tints - typically above 5500°K. The neutral white tints are typically in the 5500°K to 4000°K range. Warm white tints are below 4000°K.
The color rendering index (CRI) is an indication of a light's ability to reproduce a wide range of colors. The higher the CRI, the better the light can reproduce the full spectrum of colors.
The CRI represents the difference in spectral content between a measured light source and a black body radiator with the same color temperature and flux output and is tested using a special set of color samples. The maximum possible CRI is 100.
A typical cool white LED has a CRI around 72. Most neutral and warm white LEDs have a CRI around 82. Our neutral white LEDs have a CRI of around 87. The differences between conventional LEDs and higher CRI LEDs are quite dramatic when compared side-by-side. Skin, plants and even rocks take on a very natural tone and show much more vibrant colors.
The efficiency of a white LED depends on two different factors. The first is how efficiently the LED converts electricity into light. The second is how closely the white spectrum matches the sensitivity curve of your eyes. Remember, the lumen corresponds to the visible part of the spectrum multiplied by the sensitivity curve of your eyes. Your eyes are much more sensitive to green light than they are to red or violet light.
If you look at the spectral content of a cool-white LED, you will notice that a large percentage of the total output falls within the central part of the sensitivity curve of your eyes. So most of the cool-white spectrum adds to the lumen value. Typical cool white LEDs are weak in the red end of the spectrum and have a significant notch in the cyan part of the spectrum with a large spike in the blue part of the spectrum. This results in a color rendering index (CRI) of around 72.
On the other hand, if you look at the spectral content of a warm-white LED, you will notice that there is a significant part of the spectrum that lies to the right of the central part of the sensitivity curve of your eyes. That means there is much more red and infrared content in the spectrum. Unfortunately, much of this additional red and infrared content does not count significantly toward the final lumen value and thus effectively lowers the lumen output of the LED. This significantly lowers the overall efficiency of the LED but usually increases the CRI rating of the LED.
In between cool-white and warm-white is neutral-white. About the only thing you can safely say is that they will have lower efficiency and a higher CRI rating compared to cool-white LEDs. Unfortunately, you cannot make any blanket statements about efficiency or CRI compared to warm-white LEDs.
The phosphor conversion also contributes to the overall efficiency of the LED.
The life of an LED depends on a number of factors. The most important of these are heat and current. Our flashlights have a direct thermal path from the LED to the exterior of the flashlight to remove any heat from the LED. Then we use a sophisticated regulation technique to manage the heat and current in your flashlight which will prevent premature aging that causes reduced lumens output and protects the LED from catastrophic failure.
Constant power regulation maintains a constant amount of power to the LED and hence keeps the light output constant as the battery is consumed. Further, constant power also does the best job of keeping light output constant in spite of temperature changes in the LED. HDS Systems invented the constant power regulation system to drive LEDs and HDS Systems is the only manufacturer in the world to use constant power regulation. Our power supply precisely matches the power available from the battery to the power required by the LED to keep the power - and light output - constant. And the power supply does this very efficiently.
The sophistication and quality of the power supply determines how well the regulation circuit can maintain the brightness at a constant value and how efficiently the battery power can be delivered to the LED. The really cheap lights use the simplest and least expensive circuits which tend to do a poor job of regulation and are inefficient. Better lights use more sophisticated circuits such as switching current regulators that do a better job. However, our switching power regulation circuits do the best job of keeping the brightness constant and are the most efficient.
Switching power supply circuits that raise the battery voltage are called boost regulators. Boost regulators raise the battery voltage when the LED requires a higher voltage than the battery is providing. Boost circuits require the battery voltage to be lower than the voltage required by the LED in order to properly regulate.
Switching power supply circuits that reduce the battery voltage are called buck regulators. Buck regulators lower the battery voltage when the LED requires a lower voltage than the battery is providing. Buck circuits require the battery voltage to be higher than the voltage required by the LED in order to properly regulate.
We use a third type of switching power supply circuit that can raise or lower the voltage to match the requirements of the LED. The advantage to this circuit is that it can accommodate different types of batteries with a wide range of voltages. And it allows certain battery, LED and power combinations that would not work with a pure boost or buck circuit.
We have added further sophistication to our regulation circuits to allow multiple brightness settings, reduced tint changes when dimming the LED, regulation of the LED temperature for higher efficiency, higher reliability and safety, detection and protection of rechargeable batteries and graceful step downs in brightness as the battery is used up so you have plenty of warning allowing you time to find a safe place to change batteries.
The efficiency of LEDs can vary significantly from one LED to the next, even within the same bin code. For the same amount of input power, the light output can vary by over 40% from one LED to the next. This difference is easily to see when two otherwise identical uncalibrated flashlights are compared side-by-side. Is the dimmer flashlight defective or is the brighter flashlight an over achiever?
We have chosen to calibrate each flashlight so that every flashlight has the same specified output. This results in consistant light output from one flashlight to the next.
The calibrated process starts by setting the maximum input power to the power that provides the minimum specified runtime. The LED must be able to make the required lumen output at the maximum power or it fails calibration. If the LED is an over achiever, the power is reduced until the output drops to the specified lumen output. Notice we are reducing power, which results in longer runtimes. Statically, flashlights will provide significantly longer runtimes than the advertised minimum runtime.
HDS Systems is the only flashlight manufacturer that measures the output of each flashlight after it is completely assembled and adjusts the output of each flashlight so each flashlight will produce the specified output. This method allows the LED to heat up to operating temperature as part of the measurement process so that the flashlight's true lumen output can be measured and adjusted under representative operating conditions.
Burst mode allows you to see with maximum visual acuity without sacrificing excessive battery life. Burst can also be used in combination with lower output settings to see much further than you would ordinarily be able to see.
Burst mode works because your eyes are logarithmic but the power to generate light is more linear. That is, in order to notice a small but visible change in brightness, you need to increase light output by 1.5x or decrease light output by 0.67x.
We can use an example to illustrate what is happening. Let's say you turn your light on to maximum, which is 250 lumens. The next brightness level down is 0.67x or 167 lumens. The difference is 83 lumens - which sounds like a lot. But remember, your eyes are logarithmic and only care about the ratio - not the absolute number of lumens - so your eyes see only a small difference in output. And most people don't even notice the step down.
Now look at what happens to battery runtimes. If you did not have burst, you would have 45 minutes of runtime before the light output dropped below 167 lumens - to 111 lumens. But by using burst mode, you get twice as long - an hour and 30 minutes before your light drops below 167 lumens - to 111 lumens. That is a huge increase in runtime - and utility.
In practical situations, you only need maximum output for a short period of time because your eyes will rapidly adapt to any excess of light. Burst mode operates at maximum for 40 seconds after you release the button before dropping one brightness level. And since maximum continues to operate for as long as the button is held down, momentary maximum will run for as long as you want it use it.
Think of the following situations where you hear a noise in the distance and turn the light on to maximum to identify what made the noise. If you identify a friend, there is no need to continue to blind your friend with a bright light. If you identified a foe, you will be running for your life or drawing your weapon within a few seconds. In either case, you only need absolute maximum for a relatively short period.
Your flashlight is much less efficient when producing the absolute maximum output compared to when it is turned down just one brightness level. This is due to a combination of battery, circuitry and LED characteristics that degrade at an N-squared rate. Thus, to maximize battery life, you want to limit the amount of time you spend using the absolute maximum output. Burst mode takes care of this automatically for you. After 40 seconds on maximum, the light steps down one brightness level. Although there is just a slight visual difference between the maximum output and the next level down, the difference in battery life is huge. And in most situations, you will probably not even notice the step down.
The brightness levels on our flashlights are spaced so that the difference between any adjacent brightness levels appear to be a small but equal change. This visual spacing takes advantage of the logarithmic nature of your eyes to see a huge dynamic range - from very bright midday summer scenes to dim moonlit scenes. Each brightness level is separated by a ratio of 1.5:1 - enough to provide a small but noticeable difference between brightness levels.
There are two common ways to dim an LED. The first way to dim an LED is to turn the LED on and off very rapidly at full power. If the light is off for 50% of the time, you will perceive the light to be half as bright. This is called PWM (Pulse Width Modulation) and results in an annoying flicker - especially at low light levels. It also results in lower overall system efficiency.
We use a more sophisticated algorithm for dimming the LED that minimizes both the amount of tint shift and the annoying flickering while increasing the total system efficiency.
Acme threads are trapezoidal thread forms that are superior in every respect to the conventional V thread forms used in most products. Acme threads are stronger, less likely to cross-thread and will last much longer than conventional V threads. Acme threads are used in precision machinery and in applications requiring the most robust threads available.
We use Acme threads throughout our lights because they are the best threads available.
The purpose of a lens is to transmit as much light as possible. As the light passes though an untreated air/lens surface, roughly 5% of the available light is reflected back. This reflected light is wasted. A glass lens has two air/lens surfaces - one on each side of the lens and thus 10% of the light can be lost.
In addition to using ultraclear glass for our glass lenses, we apply an anti-reflective coating to both lens surfaces to reduce the amount of reflected light and thus increase the amount of light transmitted through the lens. Both surfaces are coated to maximize the amount of light the lens can transmit. This increases the efficiency of your flashlight and allows 97% of the light to be transmitted out the lens.
An anti-reflective coating is a vapor deposition coating that is applied in a vacuum. The coating is a fraction of a wavelength of light thick and acts like a tuned circuit in electronics to match the "impedance" between the lens and the air. This allows the lens to capture and transmit the light that would otherwise be reflected.
The anti-reflective coating is fairly durable but it is very thin. Excessive rubbing will abrade the coating on the exterior surface. Paper-based towels are very abrasive and should never be used to clean or wipe the lens. Flushing the lens under running fresh water and then blowing or shaking off any remaining water is best. However, even if you rub off the coating or it becomes soiled and stops working, you will only reduce the output by a small amount - which is not significant.
Anodize is a hard protective coating formed on the surface by a special electrochemical process. In the case of aluminum, the layer is a crystalline form of aluminum oxide and is similar to synthetic sapphire (corundum). The anodize is very hard and becomes quite scratch resistant when the layer of anodize is thick enough.
There are two common types of anodize used to protect aluminum products. The first is a thin clear decorative coating that can be dyed vibrant colors. This is called Type 2 anodize. Although the layer is very hard, it is very thin and relatively delicate. A sharp object can easily penetrate the layer and cause a scratch in the coating. Also, because the layer is so thin, it will be rubbed through in a relatively short period of time.
The second common type of anodize is called Type 3 or hard anodize. This is a thick dark olive coating that is very scratch resistant and wears well. This coating is often referred to as military hard anodize. Although Type 3 anodize can be dyed, colors other than black are not used because other colors come out muddy and very dark.
Type 3 anodize can vary in color from a medium gray to a dark olive before it is dyed. This color variation is common and normal - even within the same batch of parts. Slight variations in current density, bath chemistry and even temperature will affect the final color. Adding black dye dramatically reduces the color variations - and the resultant complaints about color matching.
Type 3 anodize can also vary in surface smoothness. The surface texture is a result of the final machining operation and the processing steps just prior to the anodize step. Variations are normal - although we attempt to keep the variations to a minimum.
AlTiN is an acronym for Aluminum Titanium Nitride. AlTiN is a dark colored vapor deposition coating that is applied in a vacuum. AlTiN is so tough and hard it is used to coat machine tools, drill bits and other wear surfaces to make them last longer. In addition to wearing better than hardened steel, AlTiN imparts a beautiful purple-black color to the surface it is applied to.
We use AlTiN to provide a dark coating to our stainless steel bezels and stainless steel pocket clips. We have found that this coating will out-perform military Type 3 hard anodize.
Ceramic is a tough material. A new ceramic coating was recently introduced that comes in many colors and holds up well in hard use. It is a two part material that requires a heat cure. Our baked-on finish is tougher than similar one-part room-temperature coatings, powder coats or paints. Although the baked ceramic coating is tough, it is not as tough as military Type 3 hard anodize.
We apply our finish to aluminum parts directly over a prepared military Type 3 hard anodize finish. The anodize provides a good base for the application. We apply our finish directly to our stainless steel bezels after appropriate surface preparation.
The ceramic coating is available in muted colors including tan, dark earth and olive drab and bright colors including pink and orange.
Your eyes respond to light in a logarithmic way. That means they require a significant percentage change in light output for your eyes to notice a small but visible change in brightness. A 50% (1.5x) increase or 33% (0.67x) decrease will produce a small but visible change in brightness. An increase or decrease of half that - 25% (1.25x) and 20% (0.80x) respectively - will probably not be noticed.
You are probably already familiar with logarithmic scales in other areas of your life. For instance, earthquakes are measured using the logarithmic Richter scale. Sound is measured in logarithmic decibels. If you are a photographer, you are familier with the logarithmic f-stops and the logarithmic progression of shutter speeds. Logarithmic scales make it much easier to represent very large variations from tiny to huge because the scale represents a progression of ratios instead of a progression of linear units. The perception of most physical phenomena by our bodies - sight, sound and touch - are essentially logarithmic. It is difficult for us to perceve small percentage changes.
Many people are surprised to find out that going from 0.17 to 0.25 lumens looks the same as going from 167 to 250 lumens. From your eye's perspective, the step size is the same in both cases. Notice that in the first case we only increased by 0.08 lumens while in the second case we increased by 83 lumens - a difference of 3 orders of magnitude.
Your eyes respond to light in a logarithmic way. That means they require a significant percentage change in light output for your eyes to notice a small but visible change in brightness. A 50% (1.5x) increase or 33% (0.67x) decrease will produce a small but visible change in brightness. An increase or decrease of half that - 25% (1.25x) and 20% (0.80x) respectively - will probably not be noticed.
So what is the practical difference between two flashlights with different outputs? If the difference is small - around 25% - you will probable never see the difference. If the difference is larger - around 50% - will will see the difference but it will be a small difference. If the difference is much larger - around 100% - you will be able to see the difference easily, but you may be surprised that it does not appear to be larger.
Here are some more examples. The average person will not notice the difference between 140 and 170 lumens, 170 and 200 lumens or 200 and 250 lumens. However, you will notice the difference between 140 and 200 lumens or 170 and 250 lumens.
The differences in LED efficiency has a significant effect on runtime. In general, the amount of power needed to generate the maximum output is the same. The higher light output is the result of higher LED efficiencies. The practical reason for having a higher output flashlight - even if you do not think you really need that much light - is that the lower output settings will have much longer runtimes.
We are going to show you a simple method to take advantage of how your eyes work and how your flashlight works to see the furthest possible distance - further than you can see with other flashlights with the same output rating. But first, you need some additional information so you understand how this method works.
The first thing to understand is that your eyes are marvelously adaptive. If you expose your eyes to a brightly lit scene, they will reduce their sensitivity to light - effectively throwing away the excess light. On the other hand, if you expose your eyes to a dimly lit scene, your eyes will increase their sensitivity to light - effectively becoming more efficient at gathering the available light. Thus, you want to use an appropriate amount of light for your task without over illuminating the scene.
The second thing to understand is the Inverse Square Law - it takes 4 times as much light to see twice as far - all else being equal. This is because at twice the distance the light has spread out to 4 times the surface area and is thus 1/4 the brightness. So to illuminate the distant surface to the same brightness level, you need 4 times the amount of light.
And finally, your eyes are logarithmic in their response to light. In simple terms, if you double the amount of light you will see an easily recognized increase is brightness. This is true whether the increase is from 1 to 2 lumens or 100 to 200 lumens. They both appear to be equal increases to your eyes. The change in output between levels on our flashlights are visually even and are separated by 1.5x increases for a small but noticeable difference.
In practical terms, this means you can increase the output by one level (1.5x) and see 22% further, two levels (2.3x) and see 50% further, 3 levels (3.4x) and see 84% further or 4 levels (5x) to see 125% further - over twice as far. This assumes the same level of dark adaptation has been maintained.
We will use two scenarios to illustrate the best use of your flashlight and how using this new technique will allow you to see much further than you can see with an ordinary flashlight.
In the first scenario, you turn your light on to the maximum setting and go for a walk. After 40 seconds, your flashlight will automatically steps down to one setting lower to maximize runtime without making a significant visual difference. Most people do not notice the step down under typical conditions of use. It is difficult to not over illuminate the are just in front of you so you will have a compromised level of dark adaptation. As you are walking along, you hear a noise so you point your light at the noise. Pressing the button will reactivate the maximum output allowing you to see 22% further than without it. In any case, the distance you can see is limited by your compromised dark adaptation.
For the second scenario, we will assume you use a much lower setting to take your walk - perhaps just a fraction of a lumen. If you point the light a few body lengths in front of you, you have plenty of light to see with and you maximize your dark adaptation. Again, you hear the noise, point the light at the noise and push the button. But this time, you can see over 20 times as far as you can see before pushing the button. That certainly sounds impressive but can you really see any further than in the first scenario?
The answer is yes - by a large margin. The absolute maximum light output is the same in both scenarios so why can you see further in the second scenario? The answer is dark adaptation. With the bright light in the first scenario, it is difficult to avoid over illuminating the scene and ruining your dark adaptation. With the dim light in the second scenario, it is easy to build your dark adaptation, which counts as several additional brightness levels when you turn on the maximum output. Two additional brightness settings allow you to see 50% further. Three brightness settings allow you to see 84% further. Four brightness settings allow you to see 125% further - that's over twice as far.
During the second scenario you have not asked your eyes to suddenly increase their dark adaptation - which they cannot do anyway. By allowing your eyes the opportunity to adapt to lower light levels and then working with that level of dark adaptation, you have significantly increased the effective range of your flashlight.
The other benefit from the second scenario is runtime. In the first scenario, you will be replacing your battery in a couple of hours. In the second scenario, you can stay out several nights without needing to change your battery.
If you use your flashlight on a regular basis, the cost of ownership is primarily a function of the hourly cost of operation. Efficiency and best practices are the keys to maximizing battery life and obtaining the lowest cost of ownership without sacrificing the utility of your flashlight.
An example will illustrate how this works. For this example, we will assume a premium battery costs $1.75.
Let's consider a 250 lumen EDC LE, which will run for 3.25 hours on the tactical brightness setting before dropping below 50 lumens. This yields an operating cost of $0.54 per hour ($1.75/3.25 hours). In 100 hours, the EDC LE will cost you $54 to operate. If we add in the price of the flashlight ($199), the total cost of ownership for the first 100 hours is $253.
Now let's take a typical 2 battery incandescent tactical flashlight. You can usually get 1 hour of operation at 65 to 75 lumens before you have to replace the batteries. This yields an operating cost of $3.50 per hour for the batteries. Plus you will have to replace bulbs at least once per 15 hours at $15 each for an operational cost of $1.00 per hour for bulbs. In 100 hours, the 2 battery incandescent tactical flashlight will cost you $450 to operate. If we add in the price of the flashlight ($65), the total cost of ownership for the first 100 hours is $515.
Notice that the less expensive 2 battery incandescent tactical flashlight has twice the cost of ownership in the first 100 hours - even though the EDC LE purchase price was three times higher. The EDC LE is far less expensive to own and operate compared to a typical 2 battery incandescent tactical flashlight.
The cost of ownership becomes even more exaggerated when comparing most flashlights to the 250 lumen EDC Executive. The EDC Executive 250 lumen flashlight operating cost is a mere $0.07 per hour ($1.75/24 hours) - or $7.30 for the first 100 hours of operation. The total cost of ownership for the first 100 hours - including the $199 purchase price - is $207.
The cost of ownership can be reduced even further by using rechargeable lithium-ion batteries. Even if you replace the rechargeable batteries on a regular basis, you are only looking at pennies per hour operating expense for the EDC LE and a fraction of a penny per hour operating expense for the EDC Executive. Now that is a truly low cost of ownership.
There is no one "best" beam pattern for all situations. For instance, focusing all the light into a very narrow beam may be perfect for looking at an object at great distances. However, it is lousy for walking across rugged terrain because the central beam illuminates a very small area and the contrast is too high to see anything outside of the central beam. Conversely, a flood light is great for evenly illuminating a large field of view at close range but is lousy for seeing something distant.
The Inverse Square Law of light tells us that if we double the beam width we can only see half as far but we can see four times the area compared to the original beam - assuming the same surface brightness at both distances.
The optimum beam pattern is the one that is most useful for your application. This requires a balance between the light in the center of the beam and the light in the outside of the beam and an appropriate transition between the two. For instance, it is better to have a beam with a soft transition from the center to the edge and a relatively low contrast ratio across the beam for a headlamp or use in rugged terrain. For general flashlight use, having more light toward the center of the beam is often desired.
The beam pattern can have a significant effect on the apparent brightness of a flashlight when comparing two flashlights having the same lumen output. A narrower beam will appear brighter and throw further while a wider beam will appear dimmer and have a shorter throw but wider spot.
We do not overdrive our LEDs because overdriving an LED produces excessive heat, reduces the efficiency of the LED, reduces runtimes, reduces the reliability of the LED and rapidly ages the LED - which permanently reduces light output.
For maximum reliability and safety, we monitor and regulate the temperature of the LED. Heat is the primary enemy of your LED and so regulating the LED temperature prevents premature aging, increases reliability and increases efficiency. In addition, regulating the LED's temperature prevents the flashlight from becoming dangerously hot and injuring someone who touches it.
The efficiency of LEDs vary from one LED to the next. Therefore the amount of power it takes to generate the same amount of light will very from one LED to the next. We have chosen to hold the light output constant from one flashlight to the next. This results in constant light output but causes variations in runtimes from one flashlight to the next. We specify a minimum runtime at the rated light output. Typical runtimes will be 20% higher than the minimum runtime.
The type of battery used will have an impact on flashlight runtime. The most significant difference in batteries is how they handle the highest power levels. You should always choose permium batteries that can handle high continuous currents.
Temperature can also have a significant impact on flashlight runtime. As the battery temperature drops, the performance of the battery will deteriorate. How much power is lost with temperature depends on many factors, including power draw and battery chemistry. Lithium chemistries are preferred for cold environments.
The length of time your battery will last is referred to as the runtime and is dependent on several factors. We provide two different runtimes - tactical runtimes and ANSI runtimes. We always list the ANSI runtime, which is defined as the runtime down to 10% of the origional lumen output. If a particular setting produces over 50 lumens, we also list a tactical runtime, which is defined as the runtime down to 50 lumens.
The tactical runtime is a shorter and more realistic runtime for someone using a flashlight in tactical applications - such as law enforcement, security patrol or self-defense - conditions under which only tactical levels of light are acceptable. The ANSI definition of 10% is just too dim to be useful for tactical situations.
HDS Systems is the only manufacturer to calibrate flashlights to a specified lumen output. Efficient LEDs need less power to generate the calibrated amount of light and will have longer runtimes as a result. Our specified runtimes are minimum runtimes with typical runtimes being longer. If a particular light cannot be calibrated to 250 lumens while meeting the minimum runtime, it will be calibrated to 200 lumens (or lower) in order to meet the minimum runtime. The calibration process ensures the minimum runtime is always met. However, the actual runtime is typically better than specified.
Battery performance is dependant on several factors including power draw, battery quality and temperature. Premium quality batteries are required to get full performance from our flashlights. Poor quality batteries will result in poor performance - it's that simple. Low temperatures will reduce a battery's performance. Lithium batteries will continue to work down to -40°C (-40°F) but their performance is significantly reduced by that temperature. Battery performance peaks a bit above body temperature.
All runtime tests are conducted in an integrating sphere at room temperature using American made premium quality primary (non-rechargeable) lithium batteries. We use Battery Station brand batteries for our testing.
How does power level affect battery runtimes? As a rough approximation, every two levels brighter will halve the battery life and every two levels dimmer will double the battery life. You can maximize battery life by using the minimum brightness level compatible with the task you are performing. The lowest brightness setting will help preserve your night vision adaptation without using a red filter.
The main difference between primary and rechargeable batteries is that primary batteries are used once and thrown away while rechargeable batteries can be used and recharged hundreds of times. This can make a dramatic difference in the overall cost of operation of your flashlight. If you assume $1.67 for primary batteries and $54.00 for two rechargeable batteries and the charger, the break even point is at 32 primary batteries.
Rechargeable batteries have a lower power capacity than a primary battery. However, you can swap a partially used rechargeable battery for a fully charged one so you always leave home with a full capacity battery. People that use primary batteries usually find it too expensive and wasteful to put in a fresh battery until the current battery is mostly depleted. Thus primary battery users often leave home with less available runtime than if they had used rechargeable batteries.
Primary batteries will retain more total capacity at lower temperatures than rechargeable batteries. And primary batteries will operate to lower temperatures than rechargeable batteries.
Rechargeable batteries can be damaged by over-charge, over-discharge or reverse charging so these conditions must be prevented. Lithium-ion (Li-ion) batteries are electrically delicate and special precautions must be taken to ensure safe use of thes batteries. When used within their design limits, Li-ion batteries are both safe and inexpensive over the long term and we recommend their use with our products.
There are several different kinds of Li-ion batteries currently on the market but only certain kinds can be used safely with our products. The common Li-ion chemistries are Lithium Cobalt Oxide (LiCoO2), Lithium Manganese Oxide (LiMn2O4) and lithium iron phosphate (LiFePO4).
Both the Lithium Cobalt Oxide and the Lithium Manganese Oxide Li-ion battery chemistries operate at a higher terminal voltage - 4.2V when fully charged with a nominal voltage of 3.6V - 3.7V. These are the only two Li-ion battery chemistries supported by our products.
Do not use the new lithium iron phosphate batteries with our products. Although this is a very safe battery chemistry, it cannot be reliably distinguished from a primary lithium battery and must not be used.
The Lithium Cobalt Oxide chemistry is more common due to its higher capacity but these batteries should always contain a protection circuit for safely. The Lithium Manganese Oxide chemistry has a lower overall capacity but it is considered safe enough to be used without a protection circuit in the 123 battery size. The capacity of a 123 (17345) Lithium Cobalt Oxide battery with a protection circuit is essentially the same as the capacity of a 123 Lithium Manganese Oxide battery without a protection circuit at higher power settings. The advantage of the 123 Lithium Manganese Oxide battery without a protection circuit is better performance at the highest power setting.
Li-ion batteries are sensitive to temperature. Higher temperatures accelerate aging and contribute to the permanent loss of capacity. Li-ion batteries may be used from -20°C (-4°F) to 45°C (113°F). However, they should be brought to room temperature before recharging - from 15°C (59°F) to 35°C (95°F).
Over-charging takes place when a charger does not properly regulate the charge voltage or current. Many (most) chargers continue charging to the high side of 4.2V and do not cut off after charging is complete This will damage the battery over time and reduce the number of charge cycles. Only use a high quality charger and remove batteries from the charger when the batteries are fully charged.
A high quality charger will either cut off the charging power when the battery reaches full charge or will use a voltage that is slightly lower than the maximum value. If a lower voltage is used, such as 4.1V, the battery can be left charging for an extended period without damage to the battery. When properly charged, a battery will accommodate 500 or more recharge cycles over a multi-year period. You are better off recharging a Li-ion battery after less use and more often rather than after longer use and less often.
Over-discharge takes place when the cell voltage is allowed to drop below a specified minimum voltage. For Li-ion batteries, this is around 2.7V. However, most of the charge has been removed by the time the battery reaches 3.0V. Any device that uses Li-ion batteries must be built to specifically recognize a Li-ion battery and to warn the user prior to reaching these limits. If the user does not heed the warning, the device must turn off to prevent over discharge.
All high quality Lithium Cobalt Oxide Lithium-ion batteries sold today contain a protection circuit to prevent over-discharge. When the protection circuit detects an over-discharge, it turns off the battery. This effectively causes the sudden failure of the device containing the battery. Our flashlights identify and properly handle Li-ion batteries and prevent this sudden failure by gracefully stepping down through the power levels as needed and then blinking the lowest power level.
It would be dangerous to simply turn off the flashlight unexpectedly to prevent over-discharge. Instead, our products reduce the output brightness as the battery is discharged. When the lowest brightness is reached, your flashlight will begin to blink about once a second. When your flashlight begins to blink, you should immediately find a safe place to change your battery, wait for the sun to come up or wait for rescue. Your light will continue blinking for an unspecified amount of time before the voltage reaches a critical level for the battery and your flashlight turns off to preserve the battery. You can turn your light back on again for another short burst of light as needed.
Reverse charging takes place when you have several batteries in series and one of the batteries is weak. The weak battery is over-discharged and then driven into reverse charge by the stronger batteries The mechanism discussed above effectively prevents reverse charging. So does using a single battery.
The 123 battery size is known by many names: 123A, CR123, CR123A, ANSI/NEDA 5018LC and IEC CR17345 and these names normally are used for primary (non-rechargeable) batteries. Putting an R in front of the name is a common way to distinguish a battery as a rechargeable battery. Hence a R123 is just a rechargeable 123. In the 123 battery size, rechargeable batteries are always lithium-ion (Li-ion) batteries.
In the international cell size designations, the first two digits are the diameter in millimeters and the last three digits are the length in tenths of a millimeter. Thus an IEC CR17345 battery will be 17mm in diameter and 34.5mm long. It is common usage to shorten the IEC designation to just the 5 digits - i.e., 17345 instead of IEC CR17345.
A typical protected R123 (R17345) is manufactured using a 16340 rechargeable Li-ion cell. By the time you add the protection circuit, the resulting battery grows to the 17345 size. It is incorrect to refer to these batteries by the internal cell size. Batteries should always be referred to by their true external size. Unfortunately, many battery vendors refer to protected batteries by the internal cell designation used to build the protected battery.
In the international cell size designations, the first two digits are the diameter in millimeters and the last three digits are the length in tenths of a millimeter. Thus an IEC CR17670 battery will be 17mm in diameter and 67.0mm long. It is common usage to shorten the IEC designation to just the 5 digits - i.e., 17670 instead of IEC CR17670.
Putting an R in front of the name is a common way to distinguish a battery as a rechargeable battery. Hence a R17670 is just a rechargeable 17670. In the 17670 battery size, rechargeable batteries are always lithium-ion (Li-ion) batteries.
A R17670 battery has more than double the capacity of a rechargeable 123 size battery (R17345) and will provide over twice the runtime compared to the smaller battery.
Most manufactures advertise both bare R18650 cells and protected R19670 batteries as being 18650 batteries for historic reasons. When 18650 cells first came out many years ago, they were only available in the unprotected format so the 18650 size designation was correct. But over time, protection circuits were added to the 18650 cell for safety reasons. Adding the protection circuit increased the size of the resulting battery to 19670. Hence the proper size designation for a protected 18650 cell is 19670. But because these protected batteries were built around the original 18650 cells, most of the suppliers continued to use the older incorrect 18650 designation instead of the newer correct 19670 designation. This has proven to be very confusing to most customers.
More recently, higher capacity batteries have been introduced, providing capacities of 3400mAh and higher. Although they are based on cells norminally called 18650, the completed battery size is typically 19700.
A R17670 battery has roughly 70% of the capacity of the standard capacity R19670. In most applications, this will not have a significant impact on the utility of your flashlight. For most applications, you will find the R17670 will last a full shift. And for those marginal cases, carrying a second battery to swap part way through the shift will provide plenty of cushion.
We do not recommend you use your flashlight as a dive light. The rotary seals are not designed to seal when in motion and the water pressure will eventually press the button - as if you were pressing it manually. However, you can configure the flashlight so the press-and-hold preset setting is the same as the turn on preset setting so water pressure activating the switch will have no unexpected effect.
If you get water inside the battery compartment - especially salt water - the battery voltage will power electrolysis and release an explosive mixture of hydrogen and oxygen gas. Electrolysis will also cause corrosion.
If water gets into the battery compartment, rinse the battery and the interior of the battery compartment with fresh water and dry.
The pocket clip for the EDC Executive and EDC LE flashlights installs between the battery compartment and the switch cap in a special groove between the two items. Your flashlight is shipped without the pocket clip installed. Instead, an optional external O-ring has been placed in the groove for a nicer appearance.
Follow these steps to install your packet clip:
The installation is now complete. You may want to save the optional external O-ring if you later remove the pocket clip - to provide a nicer exterior appearance. However, the optional external O-ring is not necessary and can also be thrown away.
There is an external groove between the switch cap and the battery compartment that will accept a bezel down pocket clip. When the pocket clip is not installed, an optional thin O-ring may be placed in the groove to improve the exterior appearance. The optional external O-ring has no effect on the operation of the flashlight and is not required.
The groove width can be adjusted by loosening or tightening the switch cap slightly, and should be adjusted to be large enough to allow the O-ring to sit down into the groove so it is flush with the outside surface. This provides the best appearance and keeps the O-ring recessed so it will not snag on anything.
Tail standing is not an advertised feature. The air-tight seal on the battery compartment can cause the flush button to bulge out when the air pressure inside the flashlight is higher than the outside air pressure. Changes in elevation, weather and temperature can affect the relative air pressure within the flashlight.
You can improve tail standing by equalizing the air pressure inside the flashlight. The easiest way to accomplish this is to loosen the switch cap until you can see the O-ring that is normally covered by the switch cap. The entire O-ring should be visible. Then, gently press the button and hold the button down while screwing the switch cap back down. You can release the button once the O-ring has been completely covered by the switch cap. The switch will probably activate while you are screwing down the switch cap - this is normal.
The same procedure can be done with the head - such as would happen when changing the battery. However, older battery compartments with V-threads do not have the vent hole and will not produce the same results. This is because the head threads are usually coated with a generous amount of grease and that grease will seal the threads long before reaching the O-ring seal, thus trapping and compressing a large volume of air. The switch cap threads typically have a minimal amount of grease and so those threads will leak air until the O-ring is reached, minimizing the amount of trapped and compressed air.
HDS Systems designs and builds its flashlights in Tucson, Arizona from parts that come from all over the world. We prefer using American parts whenever practical, but sometimes it is just not possible. As we build leading edge flashlights, we must have top-of-the-line parts to make our designs work. For example, we use the best LEDs available. Even though the wafers - the heart and sole of the LED and the part that converts electricity into light - are manufactured in the USA, the wafers are packaged into LED emitters outside the USA, so the LEDs are considered to be of foreign origin. The microprocessors used to control our flashlights are similar - the wafers are manufactured in the USA but packaged outside of the USA and hence they are not considered to be made in the USA. The major electronic components mostly come from overseas because the required top quality power transistors and power capacitors are not made in the USA.
All of the design, testing and assembly work is done in the United States. And our machined parts are manufactured in the USA. So the overwhelming majority of value in each flashlight comes from the United States.
In order to claim "Made in the USA", the Federal Trade Commission (FTC) says a product must be "all or virtually all" made in the United States. They define the phrase "all or virtually all" to mean that all significant parts and processing in a product originate in the United States. We consider the LED and other major electronic components to be significant components.
We think we are disqualified from making the "Made in the USA" claim for our flashlights because the LED and major electronic components are not "Made in USA". We prefer to error on the side of not making the claim rather than making an inappropriate or misleading claim of "Made in the USA". We think this is in the spirit of the FTC "all or virtually all" rule.
Although we do not claim "Made in the USA", our products comply with the Buy American Act and are "Produced in the USA".
The European Union (EU) has a body of standards and regulations for safety, interference and environmental considerations. The three primary standards of interest are CE, RoHS and WEEE.
CE is similar to the Underwriters Laboratory's UL rating and the FCC's interference standards. To receive the certification you submit your product to a certification laboratory to be tested. Our flashlights have passed CE testing and are CE certified.
RoHS stands for Restriction of Hazardous Substances Directive. This directive has to do with the removal of certain "hazardous" materials from newly manufactured equipment. Lead - which typically makes up 37% of solder - is one of the listed materials. As of July 2006, EU law forbids the importation of non-compliant products unless imported under one of the many exemptions.
The problem with RoHS is that it legislated changes in the manufacturing process prior to there being a demonstrated reliable alternative process. RoHS compliance currently requires the use of brittle no-lead solders, more difficult to solder surfaces and higher processing temperatures. These three things have detrimental effects on the reliability of all products. Further, many RoHS surfaces incorporate a tin coating, which can grow tin whiskers, producing short circuits months or years after the product was built.
It is interesting to note the list of equipment exempt from RoHS: military, national security, medical, aviation, monitoring and control and transportation vehicles. What do all of these exemptions have in common? Reliability. Suffice it to say we will not be RoHS-compliant until we can build reliable products with RoHS-compliment methods. In the mean time, you can purchase our products under one of the listed exemptions.
WEEE stands for Waste Electrical and Electronic Equipment Directive. This directive requires that the "producer" collect, treat, recover and recycle old products rather than dispose of these old products in land-fills. This directive generally became effective August 13, 2005.
In order to comply with this directive the "producer" is required to take financial responsibility for processing end-of-life products. In this case, the EU importer is considered the "producer" and thus must make provisions for assessing customers and administering any required fees to take care of disposal using an EU-qualified disposal method. There are exemptions for military, national security and other types of equipment.