EDC-series
Frequently Asked Questions
Please review the following frequently asked questions. Please also review the User's Guide for each product and the product comparison chart. If you still have a question after reviewing this material, please contact us by e-mail or phone.
Should I order the glass lens or the polycarbonate lens?
The ultra clear coated glass lens is 98% transparent, meaning it is very efficient. Since it is made of glass, it resists scratching better than the polycarbonate lens. Although the glass is quite strong, if dropped for head height in a 45° down orientation, the lens is likely to break due to deformation of the bezel. Once deformed, the head must be replaced in order to fix a broken glass lens. There is a small charge to replace a damaged head and lens.
The plastic polycarbonate lens transmits about 88% of the light, making it less efficient than the ultra clear coated glass lens. The polycarbonate lens is also easier to scratch than the glass lens but the scratches tend to accumulate toward the center of the lens where they have the least affect on light output. However, the polycarbonate lens is nearly unbreakable and will tend to remain water-tight even after the bezel has been damaged. The polycarbonate lens is recommended for applications where maximum ruggedness is required.
All light measurements are made with the ultra clear coated glass lens. Using the polycarbonate lens will reduce your flashlight's output.
How far can I see with my light?
There is no industry standard for measuring the distance you can see with a light. In order to measure the distance you can see, you have to define the surface illumination and the surface area to be illuminated. Let me explain.
A flashlight beam emits a certain amount of light. That light travels some distance between the flashlight and the object you are trying to illuminate. As the light gets further from the flashlight, its ability to illuminate the object decreases by the inverse square of the distance. That is, if you move the object twice as far away the surface brightness (luminous intensity) will decrease to 25% of the original surface brightness. But at the same time, the flashlight will illuminate 4 times the surface area. Or if you move the object 10 times as far away the surface brightness will decrease to 1% of the original surface brightness while illuminating 100 times the surface area. This is known as the Inverse Square Law of light. As you can see, you have taken the same amount of light and spread it over a larger surface area with a corresponding decrease in surface brightness.
Let's say your flashlight can illuminate a surface to 1500 lux at one meter. At 10 meters (33 feet) you can illuminate the surface to 15 lux. If you pick 2.5 lux as the required brightness, you can see 25 meters (80 feet). if you pick 1 lux as the required brightness, you can see 39 meters (127 feet). If you pick 0.1 lux - the brightness of full moon light - as the required brightness, you can see 122 meters (402 feet). The practical limit on distance is controlled by your level of dark adaption, beam pattern and other factors.
How can you apply this in a practical way? Let's assume your eyes have adapted to a low brightness beam while taking a walk with the beam pointed a few body lengths in front of you. You hear a twig snap in the distance - is it friend or foe? You point your light into the distance but the inverse square law effectively "dims" the light - making it difficult or impossible to see the distant object. Press the button to get the high setting and suddenly the distant object is well illuminated. After you have identified the distant object, release the button and go back to your walk. During this process you have not asked your eyes to suddenly change 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 adaptation, you have increased the effective range of your flashlight many times.
Which beam pattern is best?
There is no one "best" beam pattern. For instance, focusing all the light into a very narrow beam may be perfect for looking at an object at great distances but is lousy for walking across rugged terrain because the contrast is too high to see outside 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 with the same surface brightness but we can see four times the area with the same brightness at the closer distance.
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.
Why is power to the LED regulated?
Power regulation maintains a consistent amount of power to the LED and hence keeps the light output constant as the battery is used up. The regulation circuit - also called a power supply - transfers a specific amount of power from the battery to the LED while converting the battery voltage.
The sophistication 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 simplest or least expensive circuits tend to do a poor job of regulation and/or are inefficient. More sophisticated circuits, such as switching current or switching power regulation circuits can do a very good job of keeping the brightness constant and can be quite efficient, but tend to be more expensive.
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.
There is a third type of switching power supply circuit used by HDS Systems that can raise or lower the voltage to match the requirements of the LED. The advantage to this circuit is that it can accommodate many different types of batteries within a wide range of voltages. And it allows certain battery, LED and power combinations that would not work with a pure boost circuit or a pure 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 gracefully step downs in brightness as the battery is used up so you have notification and time to find a safe place to change batteries.
What is visually even brightness spacing?
Your eyes respond to light in a logarithmic way. That means that a significant increase in brightness requires a doubling in the amount of light - and power. Photographers refer to this change as one f-stop. As an example, to increase the brightness 4 full shades of brightness requires 16 times as much light. The brightness levels on your light are spaced to provide small, visually even changes in brightness. 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.
Why are the lights calibrated?
The efficiency of LEDs vary from one LED to the next. That means for a certain amount of input power the light output varies or for a certain light output the input power varies. We have chosen to hold the light output constant and allow the input power to vary. This results in constant light output but causes variations in the battery runtime from one flashlight to the next. We guarantee a minimum battery run time at the rated light output.
How long will the batteries last?
Battery run times depend on the brightness setting, LED efficiency, type of battery used and battery temperature. The following will help you estimate runtimes at room temperature:
| |
Duracell |
SureFire |
Battery Station |
MP Li-ion |
Battery Station Li-ion |
| 60 Lumens |
25 minutes |
20 minutes |
17 minutes |
32 minutes |
18 minutes |
| 60 Lumens XR |
38 minutes |
36 minutes |
33 minutes |
37 minutes |
32 minutes |
| 42 Lumens |
80 minutes |
75 minutes |
55 minutes |
60 minutes |
60 minutes |
| 10 Lumens |
8.5 hours |
8 hours |
6.5 hours |
5 hours |
5 hours |
| 2.5 Lumens |
37 hours |
34 hours |
29 hours |
19.5 hours |
21 hours |
| 0.3 Lumens |
300 hours * |
275 hours * |
235 hours * |
155 hours * |
170 hours * |
* These values are calculated.
The 60, 60 XR and 42 lumen entries in the table are associated with flashlights having those maximum output setting. The differences in output and runtimes are due to the relative overall efficiency differences in those flashlights. The 10, 2.5 and 0.3 lumen entries are from a flashlight having 42 lumen maximum output - flashlights with higher outputs will have longer runtimes due to their increased overall efficiency.
Runtimes are based on worst-case test data using current production specifications and generally represent the shortest expected runtimes. Many users will experience significantly better runtimes. These runtimes are intended to be a guide and are not a guarantee of performance.
Why do battery runtimes vary?
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 and allow the input power to vary. This results in constant light output but causes variations in the battery runtime from one flashlight to the next. We guarantee a minimum battery run time at the rated light output.
The type of battery used will have an impact on battery runtime. The most significant difference in batteries is how they handle the highest brightness setting. You should always choose batteries that can handle high continuous currents. Alkaline batteries are a poor choice in this type of application. Lithium and nickel metal hydride are the preferred battery chemistries for high power applications.
Temperature can also have a significant impact on battery runtime. As the battery temperature drops towards and below freezing, the performance of the battery will deteriorate. How much power is lost with temperature depends on the battery chemistry and construction. Lithium is the preferred battery chemistry for cold environments.
LEDs and batteries are significantly less efficient at higher power levels. Therefore, the highest brightness levels consume disproportionately larger amounts of power and thus battery life drops at a faster rate than expected.
What is the difference between Duracell brand batteries and Battery Station brand batteries?
Duracell brand batteries are premium batteries. They provide a superior combination of high current performance and low current capacity. That means Duracell brand batteries provide top-rated performance at high currents as well as provide the longest run times at lower power settings.
The Battery Station brand batteries provide a lower overall performance. However, the Battery Station brand batteries are significantly less expensive than the Duracell brand batteries.
Why are rechargeable batteries treated special?
Rechargeable batteries can be damaged by over-discharge or reverse charging so both conditions must be prevented. Over-discharge takes place when the cell voltage is allowed to drop below a specified level as the battery is used up. The voltage below which the battery cannot safely discharge is mostly determined by battery chemistry. To prevent over-discharge, the battery chemistry must be recognized and the battery voltage must be carefully monitored.
It would be dangerous to simply turn off the flashlight to prevent over-discharge. Instead, the output brightness is reduced, which has the effect of raising the battery voltage slightly. Every time the battery voltage drops, the output brightness is again reduced to maintain the battery voltage above the safe level. Obviously, this cannot go on forever. When the lowest brightness is reached, it is assumed you have an emergency - i.e., you cannot change batteries and you still need light. At this point, we sacrifice the batteries to save your life.
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.
How long will the LED last?
The LED in your flashlight will last for 6,000 to 18,000 battery changes depending on what brightness settings you are using. In practical terms, the LED in your flashlight will never need replacing.
The life of an LED depends on a number of factors. The most important of these are heat and current. Your flashlight uses a sophisticated regulation technique to manage the heat and current in your flashlight to protect the LED from catastrophic failure and to prevent premature aging. The aging slowly reduces the light output of the LED.
Are all white LEDs the same color?
No. Achieving a consistent white color is very difficult to do with current LED technology and so each LED has a slightly different color. From the aesthetics point of view, this can be annoying if you compare two lights because they are bound to appear two different shades of white - which always leads to the question of which is whiter. White light only takes on an independent shade of color without reference to another light if the white is too distance from the Planckian black body radiator line or too distant from daylight. From a practical point of view, if both lights are used separately, each will work equally well and you may never notice one or the other has a tint.
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 stimulated the three color receptors in your eyes. This can be done with only two colors but generally requires at least three colors for acceptable results.
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. As you raise the temperature of the black body radiator, the color shifts from red toward 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 5000°K to 7000°K with typical daylight being in the range of 5500°K to 6500°K. Incandescent lights generally lie in the range of 2800°K to 3200°K and have a distinct orange cast when compared to daylight. The very 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 5469°K.
The guaranteed tint LEDs have a typical correlated color temperature in the range of 5700°K to 6300°K and lie close to the Planckian black body radiator line.
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.
What is tint control?
The typical way to dim an LED is by reducing current flow. However, as the current is reduced, the tint of the LED can shift toward the green part of the spectrum. HDS Systems uses a more sophisticated algorithm for dimming the LED which minimizes the amount of tint shift, thus preserving the original tint.
Do you over drive your LEDs?
No, we do not over drive our LEDs. Over driving an LED produces excessive heat, reduces the efficiency of the LED, 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 temperature prevents the flashlight from becoming dangerously hot and injuring someone who touches it.
Our advanced technology allows our lights to provide superior light output and battery run times without over driving our LEDs.
Is the single button interface difficult to use?
Like anything else, the single button interface takes a little bit of practice before you become completely comfortable with it. Pressing the button once turns it on and pressing the button a second time turns it off. When the light is on, other brightness settings are just a press, double-click or triple-click away. Most people find the light easy to use after they play with it for a few minutes.
Although the light has menus for setting the configuration, you normally change the configuration once or twice to customize it to your needs and then leave it that way. From then on, you turn the light on and off or make use of the other brightness settings. Once you customize the light to your needs, you may never reference the menus again.
Why are there variations in the hard anodize finish?
The anodizing process is an art as much as a science. Slight variations in time, tank temperature, tank concentration, anode current, material or part loading can make a visible difference in the final appearance of the finish. Although every effort is made to ensure consistency, there will always be slight variations in color from part to part.
If you look closely, especially at a smooth part of the finish, you will be able to see the grain of the metal. The grain of the metal is like the grain in wood - there are variations in the grain from one area to the next. This is a natural part of the finish.
You will sometimes see differences in color in the form of bands or occasional pin holes - especially in the knurling. These tend to darken with use and blend into the rest of the surface. The laser engraving will change from a bright white to muted gray with use. These are all considered a normal part of the finish.
What are the Arc4 and Arc4X?
The Arc4 is the 30 lumen predecessor to the EDC-series flashlights. The Arc4 was also know as the Arc4+ and the Arc4 Premium. The Arc4 Standard was never manufactured. The Arc4X is a 42 lumen variant of the Arc4 and only 5 were every produced.
All of the technology used in the Arc4 came from the Action Light headlamp and was repackaged to fit into the one inch flashlight form factor. HDS Systems was the exclusive developer and financier of the project. The completed design was licensed under non-disclosure to Arc Flashlight for the sole purpose of manufacturing and sales. The license was terminated for cause in April of 2004. The flashlights manufactured and sold under license were commonly know as the Arc4 Rev 1.
After the license was terminated Arc Flashlight modified the design and continued to manufacture and sell a version of the flashlight commonly known as the Arc4 Rev 2. The Rev 2 flashlights proved to be very unreliable with a failure rate estimated in the 25 to 50% range - which contrasted sharply with the Rev 1's solid reputation for reliability. Arc Flashlight closed their doors a few months later.
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