Action Light 24-3V headlamps and flashlights

The Action LightTM Technologies

Safety, Useability, Reliability, Longevity

The Action Light family uses many special technologies to provide you with the best light available. Many people are satisfied just knowing that the light uses these technologies. But there are people like yourself who want to know how those technologies work. We have provided a detailed explanation of these technologies so you can appreciate why the Action Light is so superior.

We have organized the material into the following articles:

Designing a Light For the Human Visual System

When you sit down to design a light, you always remember the obvious things like the batteries, bulb, reflector, switch and case. But do you think about how the results will work with the human visual system? Your eyes, after all, must be able to use the resulting light efficiently or the light is wasted.

In this article we will touch on the important aspects of how your eyes work, examine how current lights interact with your eyes and discuss how to optimize a light for night vision. You should skip any parts that you don't understand and perhaps come back to them at a later time.

How your eyes work

A good place to start is how your eyes respond to light. Your eyes have a non-linear (logarithmic) response to light, much like a camera. In order to notice a significant increase in brightness, you must double the amount of light. In photography, this doubling is referred to as an f-stop. For our purposes, the f-stop is a convenient unit of measure and we will use it when referencing relative brightness. To put this in perspective, if you suddenly change the brightness by 20%, you will notice just a slight change in brightness. In fact, if the change takes place over a couple of seconds, you may not even notice.

Your eye's lens system includes the iris. Your eye's iris is just like the iris in a camera - it controls the amount of light entering the eye. The size of the opening changes in response to the amount of light available. When less light is available, the iris opens to let in more light. When too much light is available, the iris closes to reduce the amount of light entering the eye.

On the back wall of the eye is the retina. The retina is covered with rod and cone cells. When plenty of light is available, the cones are used and provide the best visual acuity. However, when very little light is available, the cones no longer function and the rods take over. The rods can become very light sensitive over a 20 minute adaptation period but cannot provide the high visual acuity of the cones because the central visual area of the eye has very few rods. This is why a very faint object can be seen better if you look slightly to the side of the object rather than directly at the object - there are more rods outside the central visual area.

The eye has limited ability to see objects of different brightness, especially when they are right next to each other. It is very difficult to distinguish a dimly lit object next to a brightly lit object when the contrast is over 4 f-stops. There is a significant safety issue here because a hazard can easily hide in the dimly lit area (a hole, a rattle snake or an attacker).

The cones provide your color vision by being sensitive to three broad, overlapping bands. The three bands roughly correspond to red, green and blue. Your eyes are most sensitive to the yellow-green part of the spectrum, which also has the highest overlap and peaks of sensitivity in the red and green bands. The rods also have their peak sensitivity in this part of the spectrum although they are incapable of distinguishing color.

This is probably a good place to dispel the myths about red lights preserving your night vision. As it turns out, red is nothing special. Any light will preserve your night vision as long as it is of a low intensity. Moonlight does not destroy your night vision even though it is a full spectrum light because it is such a low intensity. What is important here is keeping the contrast low between what you must adapt to and any lighted surfaces.

The appearance of color objects is dependent on the color of the illuminating light source. Different light sources provide different spectrum and thus the same object can appear to have very different colors depending on the light source. This is why your local printer uses a special light booth to check color quality. Noon day sun is considered to be a full spectrum light source.

Taking advantage of your eyes

Now that you understand how your eyes work, it becomes clear what must be done to take advantage of them.

The first thing we want is high visual acuity. This is easy to achieve by simply providing enough light to let us use our cones. As long as we can perceive color, we will have high visual acuity.

The second thing we want is to minimize contrast. This takes special optics to generate a light pattern that is smooth and wide. The ideal light pattern is a central bright area where you are looking that slowly and smoothly decreases as you get further off center. There should still be sufficient light at 45° off center to see clearly. Ideally, the light pattern will extend well past 45° so your peripheral vision is covered.

The third thing we want is a high luminous intensity on the surfaces we are looking at. That way, the luminous intensity on our work surfaces can be similar to those we would find inside a well lit building. We only need to light the central visual area to this intensity as this is where our visual acuity and attention are highest.

The fourth thing we want is multiple brightness settings. The apparent surface brightness is dependant on the distance from the light to the surface. It's called the inverse square law. If we move the lamp twice as far away it takes 4 times the amount of light (2 f-stops) to get the same surface brightness. Therefore, we need to be able to adjust the amount of light to match the task we are performing.

The fifth thing we want is the spacing between brightness settings to be such that it is easy to adapt to lower light levels. If the brightness settings are spaced too close together, there is no significant difference and you tend to have "brightness creep" - always in the brighter direction. If the brightness settings are spaced too far apart, it is difficult to see while your eyes are adjusting. The optimum brightness spacing is about 2 f-stops.

And finally, we want a full spectrum light source. This is needed for accurate color identification.

What is wrong with standard electric lights

So what is wrong with existing light systems? Let me count the ways...

A conventional light uses an incandescent bulb that works by passing an electric current through a tungsten filament to heat it. This glowing hot filament is what generates the light you see. A parabolic reflector concentrates the light into a narrow and tightly focused beam.

The first major problem is less than 5% of your main visual area is properly illuminated. The typical beam is only 15° wide so that is all you get to see - a 15° part of the scene in front of you.

The second major problem is the extremely high contrast at the edge of the light beam - 6 f-stops typically. The contrast is so high it is very difficult to see anything outside of the beam. This becomes a safety issue because you may miss a hazard and become injured or worse.

The third problem is that the typical beam is blotchy. This is caused by the interaction between the bulb filament and the reflector. The bulb filament is a coil of fine wire and the reflector is smooth. Therefore, the spot is actually a poor quality image of the bulb filament. The parabolic reflector depends upon precise alignment of a point source of light. Unfortunately, a filament is not a true point source of light and so it produces an uneven spot even under the best of circumstances. This situation can be improved by using one of the more expensive facetted reflectors if one is available.

The fourth problem is that a conventional light cannot be efficiently dimmed. Because incandescent lights are black-body radiators, their efficiency is dependant on the temperature of the filament. During dimming, the filament temperature cools and the bulb rapidly loses efficiency. Because the filament temperature cools, the color temperature also shifts to the red end of the spectrum.

And finally, conventional lights are red-shifted from the ideal spectrum and preclude accurate color identification. Whereas noon day sunlight has a color temperature of 5800°K, regular incandescent lights only have a color temperature of 2800°K and appear yellow orange by comparison. Even the more expensive halogen bulbs only get to 3200°K - not much better.

You may find the following application note from Gilway Technical Lamp useful: Tungsten Filament Lamps (PDF format).

The following photographs should illustrate the differences between a standard halogen flashlight and an LED light of comparable output. The first photo is a side-by-side comparison of the two beam patterns on a wall.

High versus halogen
The beam pattern from an Action Light (left)
and from a conventional light (right)

The following scene is looking at a saguaro cactus about 30 feet (9 meters) away. The lamp is pointed about half way up the cactus..

Action Light illuminated scene Flashlight illuminated scene
As seen with the Action Light
As seen with a typical flashlight

The next scene is looking up a stream bed. The lamp is pointed at the ground about 15 feet (4.5 meters) ahead.

Action Light illuminated scene Flashlight illuminated scene
As seen with the Action Light
As seen with a typical flashlight

The following scene is looking into the distance up a stream bed. The light was pointed at the large tree about 150 feet (46 meters) upstream.

Action Light illuminated scene Flashlight illuminated scene
As seen with the Action Light
As seen with a typical flashlight

The last scene is a close look at some cactus. Notice the subtle colors.

Action Light illuminated scene Flashlight illuminated scene
As seen with the Action Light
As seen with a typical flashlight

What the Action Light does for you

The Action Light has been optimized for your eyes. The Action Light takes advantage of the way your eyes work to provide a better, safer light. The light beam is smooth and illuminates a broad area with the minimum of contrast. Multiple, properly spaced brightness settings are provided to allow you to match the amount of light produced to the amount of light needed and to make it easier to adapt to lower light levels. The light provides plenty of light for high visual acuity and can provide high luminous intensities when desired. However, the low settings allow for good dark adaptation while still providing enough light to distinguish colors and to read by. And finally, the light produces a high quality white spectrum that allows for accurate color identification.

LEDs - the Unbreakable Wonder Light

People have dreamed about an efficient unbreakable dimmable white light for years. Now that dream has become reality with the introduction of the bright white Light Emitting Diode (LED) and light systems built to use them. In this article we will touch on the basic characteristics of these fabulous white LEDs and discuss why they are superior to the conventional incandescent light. We will also touch on some of the special considerations that go into the design of a successful light using these LEDs. Some parts of this article are a bit technical and you should skip over the parts you don't understand, perhaps returning to them later.

What is a white LED?

A LED is a light emitting diode. In general terms, it is a special solid state semiconductor device that emits light. You have probably seen red and green LEDs used as indicator lights on computers, answering machines and many other devices. The high brightness white LEDs are actually a highly efficient blue LED with phosphorescent materials added to produce a high quality white light. Unlike other lighting technologies that use phosphors, the white light produced by these LEDs will generate a very complete rainbow when the light is passed through a prism.

The advantages that all solid state semiconductors share are their ruggedness, long life, compact size, low power requirements and low heat generation. All of these characteristics are very valuable when designing a light system.

The problems with conventional light bulbs

A conventional light uses an incandescent bulb that works by passing an electric current through a tungsten filament to heat it. This glowing hot filament is what generates the light you see. The filament is reasonably rugged but if you drop your light you will most likely break the tiny filament. Instant darkness. Even if you don't drop the light, the filament can only work for a small number of hours before it burns itself out. Unexpected instant darkness. This could quickly become a life threatening situation if you are in a precarious position or have no spare bulb. Think about the difficulty in disassembling your light to change the bulb on a cold, windy and rainy night in the wilderness without loosing any of the small pieces.

Another problem with incandescent bulbs is that the light is red-shifted from the ideal spectrum and precludes accurate color identification. Whereas noon day sunlight has a color temperature of 5800°K, regular incandescent lights only have a color temperature of 2800°K and appear yellow orange by comparison. Even the more expensive halogen bulbs only get to 3250°K - not much better.

Incandescent bulbs cannot be efficiently dimmed because they are black-body radiators. Their efficiency (and color temperature) is dependant on the temperature of the filament. During dimming, the filament temperature drops and the bulb rapidly loses efficiency and the color shifts in the red direction. Any reduction is voltage has the same effect.

For optimum performance, incandescent bulbs must be driven at a constant voltage with a current limit to prevent bulb failures when the switch is first turned on. However, all conventional flashlights are battery driven without any electronic voltage control or current limits due to cost considerations. Batteries lose voltage as they are used and alkaline batteries loses voltage faster than most. This is why conventional flashlights start slowly dimming almost as soon as you turn them on. By half way through the battery's life the flashlight is much dimmer than it was when the batteries were fresh.

Further, most bulb failures happen when the switch is first turned on due to the high current that flows in a cold filament. The current in the filament is regulated by temperature -- a cold filament draws far more current than a hot filament. The life of the bulb could be extended if there were proper current limiting circuitry built into flashlights.

And finally, have you ever looked at a used incandescent bulb and noticed how dark it was? What you were looking at was a layer of filament material that had been deposited on the interior of the glass. As a bulb ages, this layer of material accumulates on the interior of the glass and acts just like window tinting -- it absorbes the light and prevents it from getting through the glass envelope. An old incandescent bulb can be loosing a large part of its total light output to this tinting.

Designing a light with white LEDs

The ideal light provides plenty of high quality white light, has multiple brightness settings, never needs bulb changes, dims slowly just when the batteries are dying and can be made to run for hours on nearly dead batteries. And of course, we want to use the optimum beam pattern for best night vision. White LEDs allow us to come very close to designing the ideal light.

The white LEDs are almost indestructible. Because they are solid state devices encapsulated in plastic and physically small, they will withstand an unbelievable amount of abuse without breaking. These LEDs have an expected life of over 100,000 hours at full power - that's over 11 years of continuous operation. When run on the lower power settings, these LEDs will last for decades of continuous use.

The white light produced by the best quality high brightness white LEDs is a full spectrum white light with a superior color rendering index of 85. The light has a color temperature of 6500°K which is just slightly bluer than sunlight.

High quality white LEDs can produce 15 lumens per watt or about 1 lumen per LED. When matched to an optimized lensing system with a 20 half angle, each LED can produce a luminous intensity of 4 candela at the center of the beam. Unfortunately, because of the different beam patterns, color temperatures and eye response, it is not possible to compare the light output numbers with a conventional flashlight in any meaningful way. Therefore we have included the following photographs to make it easier for you to see the difference for yourself.

The following scene is looking at a saguaro cactus about 30 feet (9 meters) away. The light is pointed about half way up the cactus..

Action Light illuminated scene Flashlight illuminated scene
As seen with the Action Light
As seen with a typical flashlight

The next scene is looking up a stream bed. The lamp is pointed at the ground about 15 feet (4.5 meters) ahead.

Action Light illuminated scene Flashlight illuminated scene
As seen with the Action Light
As seen with a typical flashlight

White LEDs can be efficiently dimmed. As a matter of fact, white LEDs become more efficient when they are dimmed. The best efficiencies are achieved by running more LEDs at lower power settings. The great part about efficient dimming is that you can match the amount of light produced to the amount of light needed. This allows for huge savings in battery power because of the way your eyes work. Unlike their incandescent brothers, there is no large color shift when LEDs are dimmed.

You may notice slight differences in color and brightness between the LED bulbs, typically on the Low setting. These differences are normal unit-to-unit production variations which do not affect the overall functioning of the lamp. Please do not look directly into the bulbs on the Medium or High settings because they are very bright and may hurt your eyes.

The following photographs show the dramatic difference between the Action Light and a conventional light using a halogen bulb with facetted reflector. Three brightness levels are shown.

Action Light on the High setting compared to a halogen flashlight. Both lights are drawing about 1.4 watts. High versus halogen
Action Light on the Medium setting compared to a 2-cell halogen flashlight. The Action Light is drawing about 0.3 watts. Medium versus halogen
Action Light on the Low setting compared to a 2-cell halogen flashlight The Action Light is drawing about 0.05 watts. Low versus halogen
LED array

Individual LEDs are bright, but in order to produce a really bright light for general lighting applications requires an array of at least 20 LEDs. And with a proper lens system, we can generate the optimum beam pattern for best night vision.

Powering large LED arrays

For optimum results, LED arrays must be driven with a sophisticated power supply. LEDs are very sensitive to changes in voltage, unlike their incandescent light cousins. As a result, very slight changes in voltage will have a tremendous effect on the power consumed and light produced by an LED.

Large LEDs arrays also have problems with heat dissipation at high power. Whereas an isolated LED sees the true ambient temperature, an LED in the middle of an array sees the cumulative temperature of all LEDs between itself and the edge of the array. This is not an issue at low power levels, but can cause thermal runaway if not carefully controlled at high power levels.

Both of these issues are easily solved with a sophisticated power supply. The best power supplies for driving LED arrays are know as constant current power supplies and should be used because they automatically compensate for changes in temperature while the array is in operation. Switching constant current power supplies can be very efficient (>90%) so the batteries will last as long as possible.

Other benefits of a sophisticated power supply include multiple evenly spaced light settings, constant brightness until the battery is nearly dead and end of battery detection with automatic dimming to prevent you from running out of light at a critical time. By adding a microprocessor, the power supply can safely overdrive the LEDs for short periods (4 times the light for up to 60 seconds) while providing many other useful features.

Safety and nearly dead batteries

Handling nearly dead batteries is a very important safety issue so it bears looking at it in more detail. Remember we have two goals: provide a constant amount of light and provide light for as long as possible. There comes a time in every battery's life when there is only a little power remaining and it is time to give up on the constant amount of light and go for time. We have implemented our exclusive SlowDieTM circuitry to detect this condition and to slowly dim the light, no matter what setting the light is on. On the higher brightness settings, this process can take over half an hour, depending on the type and size of batteries you are using. When the light starts dimming, we recommend you switch to a lower setting.

However, the user is presented with an additional option for even greater safety. By selecting the lowest setting, the user enters into FOREVER modeTM. This special setting can extend an almost dead set of batteries to provide hours of additional light. The FOREVER mode is a great safety feature because it provides you with enough light to return to safety even on a nearly dead set of batteries.

What the Action Light does for you

The Action Light has been optimized for efficient, reliable light generation. The white LED bulbs never need replacement and are not damaged by rough handling. The light provides a bright, even, full spectrum white light that gives you the best color perception. The light provides multiple efficient brightness settings to maximize battery life. The FOREVER mode on the lowest setting keeps the light going for hours on almost dead batteries for added safety and security.

Reliable Battery Contacts, Cords and Connectors

Battery contacts, connector contacts and power cords have been the bane of electric lights since they were first invented. In this article we will discuss the important issues of reliability, contact resistance, corrosion and material selection.

Getting electricity from here to there

All electric lights require getting power from the battery to the light. Anything that interrupts the power between the battery and the light causes the light to stop functioning. Causing failures is easy. Preventing them is the difficult part.

Electricity travels through conductors such as wires or metal strips. The better the conductor, the less resistance it has to electricity. Generally, the shorter and heavier the conductor, the less resistance it has. Within a conductor, the resistance is fairly uniform and nothing will cause it to suddenly stop conducting unless something physically damages it.

Every time one conductor ends and another conductor begins we have a point of contact, usually referred to as just a contact. The electricity is passed from one conductor to the next conductor through that contact. The amount of resistance at the contact is dependent on the size of the contact area and any contamination or dirt that may be present. Small contact areas and dirty contacts are the cause of bad contacts.

From this understanding, we can now see that having large clean contact surface areas and minimizing the total number of serial contacts the power must flow through will reduce any future contact problems.

Why electric lights go bad

All the common conductors used in lights corrode. Copper and brass are the two most common conductors used in light systems and they corrode also. The oxides and salts that build up on the surface are usually poor conductors so all it takes is a thin layer to substantially increase the contact resistance and reduce the overall brightness of the light. Just the change in appearance from the bright shiny metal to a dull tarnished finish shows that corrosion has taken place. By the time you can see powdery build-ups on the surface, corrosion is severe.

Dry contacts will corrode very slowly. However, if you add water or high humidity, the rate of corrosion increases dramatically. The rate of corrosion makes another dramatic increase if you add salts, alkalies or acids to the mix.

Corrosion buildup on contacts is one of the major causes of the dim or flickering light problem. Your average flashlight has 6 to 10 contacts that the power must flow through to make the light work. Only one of those contacts needs to be bad to cause the light to fail. However, all the contacts will tend to corrode and become dirty at the same time resulting in a "tired" light.

Headlamps, with their cords and plug connectors, have even more contacts. Cords are also susceptible to another form of corrosion that is usually not seen in flashlights. The copper wires will wick water and chemicals up into the cable and cause the individual strands of wire to corrode. Over the course of time, the corrosion can be bad enough to reduce the capacity of the wire or even cause it to fail altogether.

Dirt is the other major cause of the flickering light problem. Dirt is an insulator and does not conduct electricity. So when the tiny dirt particles get in between two conductors they tend to hold the conductors apart, or only allows them to make contact intermittently as the contact moves.

Both corrosion and dirt work together to cause contacts to go bad.

Fighting corrosion and dirt

There are several methods to fight corrosion and dirt. The best method or collection of methods is dependent on the environment the device will be used in.

The first method is to isolate the conductor from the corroding environment by enclosing the conductor in a sealed container. As long as the seals remain intact there and no corrosive agents in the container, there will be no corrosion.

The second method is to pick corrosion resistant conductors. You need to choose a conductor that has all the desirable characteristics and none of the undesirable ones.

The third method is to apply a coating or plating that makes the conductor corrosion resistant. Two examples are tin plating on brass makes great connector material while tin plating on copper wire prevents the wire in a cable from corroding in harsh environments.

Dirt is very difficult to deal with because it is a good insulator, has small particles that get into everything and its abrasiveness can cause physical damage whenever it's rubbed between two surfaces. The best method is to exclude dirt whenever possible. When this is not possible, then an easy way to clean the affected area is required, with the option of replacing damaged parts.

However, the best way to prevent contact problems is to eliminate the contact all together. How? Whenever possible use a continuous conductor and then solder all connections so they no longer form a contact. An example of this is attaching connector lugs to wire. The connector lug can be crimped and be a contact or it can be crimped and soldered and thus eliminate the lug-to-wire contact.

What the Action Light does for you

The Action Light uses a combination of environmental isolation, inherently corrosion resistant materials and plated materials to solve very difficult corrosion problems. We solder all connections that are not designed to be moveable. When contacts cannot be avoided, we provide large contact areas made out of corrosion resistant materials. We picked the optimal solution that provided the highest quality and excellent durability to maximize reliability.

A few examples will illustrate our attention to detail. Lets start with the number of contacts. The Action Light All-in-One model has only 3 serial contacts: one for the switch and one for each end of the battery. All other connections are soldered.

The switch contacts are multiply redundant and swept to provide a constantly low contact resistance. Multiply redundant means there are multiple switch contacts in parallel so even if one of the switch contacts should become dirty, another contact will be functioning properly. We use swept contacts because they are self cleaning. If a switch contact were to become dirty due to a failed seal, you can clean the contact by simply working the switch back and forth between settings.

The battery contacts are large and flexible. On a conventional light, each battery contact is composed of a bent piece of metal. Because the bent piece of metal is necessarily stiff so it can hold it's shape, it will only touch the battery at one or two points with a tiny contact area and a relatively high contact resistance. The Action Lights, by comparison, use a flexible screen material that provides dozens of parallel contact points and a consistently low contact resistance. The contact material is a hard cobalt-gold especially designed for low resistance electrical contacts.

On models with separate battery packs, we use gate terminal blocks and strain reliefs to attach the cord, both at the light end and at the battery end. The gate terminal blocks provide a solid low resistance connection. The cord itself is heavy gage finely stranded tin plated copper wire for superior flexibility and corrosion resistance. The stripped ends are solder tinned. The outside jacket is extra-rugged polyurethane.

Battery Systems

The power needed to run your light is provided by a chemical battery. Each battery chemistry has its own unique set of characteristics which include size, weight, power density, rechargeability, cost and lots more. We are going to talk about the most common battery chemistries and contrast their differences.

The following table is a rough comparison between battery chemistries based on the information available from specific manufacturers -- specifications between manufactures vary widely. Numbers were scaled if no matching battery could be found. You should assume these numbers are optimistic values under ideal conditions.

"D" Size Battery Comparison
Weight Voltage
Shelf Life
(years to 70%)
Carbon Zinc 3.1oz/89g 1.5V/1.2V 6AH/4AH 25/4 3 No
Alkaline Manganese Dioxide 4.9oz/140g 1.5V/1.2V 16AH/7AH 190/9* 5 No
Lithium Sulfur Dioxide 3oz/85g 3V/2.8V 8AH/7.5AH 132/16* 10 No
Lithium Thionyl Chloride 4.2oz/120g 3.7V/3.5V 9.5AH/9AH 190/24 10 No
Lead Acid 6.3oz/180g 2.1V/2.0V 3.5AH/3.2AH 20/4 0.1 Yes
Nickel Cadmium 4.6oz/130g 1.2V/1.0V 4.0AH/3.9AH 27/5 0.1 Yes
Nickel Metal Hydride 3oz/85g 1.2V/1.1V 5AH/5AH 30/6 0.1 Yes
Lithium Ion 5.9oz/160g 4.1V/3.6V 6.0AH/5.6AH 80/12 0.3 Yes

*Actual test results using an Action Light 24-3V-series (CV) light. NOTE: these tests illustrate relative battery power relationships under specific conditions and should not be used for any other purpose. Your mileage will vary.

Comparing battery power

The first question that most people want to know is how long will my light work with a battery. The answer to that question is not simple because it depends on a large number of factors including battery size, battery chemistry, temperature, power draw and duty cycle. The best way to answer that question is to test under the conditions of use.

By looking through the table, you will see that the power density (weight divided by power -- power is roughly average voltage times current capacity) varies considerably from one battery to the next. The non-rechargeable lithium sulfur dioxide batteries are the best. They also have the best shelf life.

Internal battery resistance and wasted power

All batteries have internal resistance. The internal resistance turns part of a battery's power directly into heat and is wasted. In addition to internal resistance, a battery's capacity can drop from other effects, such as the local depletion of chemicals used to produce power, reduced effective surface area and low temperatures. For simplicity we will lump all these effects together under the term of internal resistance.

The internal resistance of a battery increases as the battery is used. The larger the resistance, the lower the battery voltage. As a direct result of this resistance, each battery has a characteristic voltage curve (voltage over time). The flatter the voltage curve, the lower the internal resistance is over the life of the battery.

Looking through the table, you will notice that some batteries have a very dramatic difference between their open voltage and their average voltage. Alkaline and carbon zinc batteries are a good example of this. As a result, much of their power is lost as heat in the battery -- especially when drawing high currents.

Take another look at the entries for the alkaline and lithium sulfur dioxide batteries. You will notice that the capacity of the alkaline cell at high currents drops to only 45% of the capacity at medium currents whereas the lithium battery can still produce over 90% of the medium current capacity at high currents. So the moral is that the actual capacity of a cell is highly dependent on the rate of discharge.

Internal battery resistance is why smaller batteries perform much worse than would be expected from the volumetric size difference. The power lost to internal resistance goes up as the square of the current and internal resistance is related to remaining cell capacity so if you were loosing 25mW due to internal resistance in a D size alkaline battery you could be loosing 110mW after the same time in a AA battery.

The internal resistance gives rise to another phenomenon you may have seen when using a flashlight. If the light gets dim, you can turn it off for a few minutes and let the batteries rest. When you turn it back on, it will be bright again -- at least for a short period. Suffice it to say that allowing the battery to rest allows the internal resistance to go down temporarily.

Recharge or throw them out

If you compare the first part of the table with the second part of the table you will see the differences between primary batteries and rechargeable batteries. Rechargeable batteries tend to have lower capacities, weigh more and have very short shelf lives but on the plus side they tend to have low internal resistance and can be very inexpensive over their life time. If you use a device often for modest periods there may be significant benefits to using rechargeable batteries.

A typical rechargeable battery can be recharged 150 to 300 times if it is properly cared for. Proper care includes recharging the battery before it becomes excessively discharged and not excessively over charging it. What this means is that you should NEVER use a rechargeable battery until it appears to be dying. If you discharge a multicell battery too far, the weak cell in the battery gets reverse charged by the stronger cells which leads quickly to its destruction and the failure of the whole battery. You should plan on using less than 50% to 75% of a rechargeable battery's capacity in any use and fully recharging it.

The recharging system is also important. First, get the recommended charger for the batteries you have. Different batteries require different charging methods and chargers are tailored to the type and capacity of battery they were designed to recharge. Second, only charge the battery for the length of time specified. Excessive charging will damage most batteries. If the charger does not automatically turn off or go into a maintenance mode and you have trouble remembering to turn off the charger, put the battery charger on a timer. If a battery has not been charged for a long time (over a month), give it a maintenance charge to bring it up to full before you use it.

All rechargeable batteries can exhibit some memory effect under the right conditions. However, most problems attributed to memory effect are actually caused by cell abuse. In general, memory effect is mostly urban legend and the average user will never see real memory effect.

What the Action Light does for you

The All-in-One model uses the lithium sulfur dioxide batteries because of their high energy density and long shelf life. This lamp was designed primarily for reliability and these batteries provide a very cost effective solution for that design.

The other Action Light models allow different configurations of batteries to be used. We supply battery packs using various battery chemistries to suit the needs of our clients. However, our clients are free to use other battery packs with these systems.

Surviving the Extremes

When someone says rugged, what comes to mind? Hot dusty deserts? Jagged wintery mountains? Pounding surf on a rocky shore? Something being thrown around and bouncing off rocks? Something being dragged through mud, sand and dirt?

Something that can stand up to these harsh conditions is a rugged piece of equipment. In this article we will talk about why things fail and how to build a rugged, reliable light system.

Brute force (or why things break when you drop them)

There is nothing more irritating than knocking something off a table and having it break. This is especially true when it was your only source of light. It is amazing to think that dropping an object just one meter (3 feet) and stopping it in 2.5mm (0.1") will generate forces of hundreds of Gs. Try it. Just divide the acceleration distance by the stopping distance to get the stopping deceleration in Gs.

When you start working the numbers, you will be amazed at the forces generated. To go further, multiply the G force by the weight of the object and start comparing that number to the strength of the materials the object is made out of. You very quickly gain an understanding of why things break.

The human body can withstand a constant 23Gs in a reclining position without injury. But as the forces go beyond that, things begin to break. The parts in your light also have their limits, although they are usually much higher.

In your conventional flashlight, the incandescent bulb is the most delicate part of the light. If you drop the flashlight from a height of 1 to 2 meters (3 to 7 feet) onto a hard surface when it is turned on, the filament in the bulb will break. Instant darkness. As the drop height increases, the case and other parts will start deforming and then breaking apart as pieces of the light head off in various directions. By the time you have dropped the light 8 meters (26 feet) the light is damaged beyond repair.

Water, mud and grit

The problem with water is that it rapidly accelerates corrosion. If you add salts or other corrosive agents, corrosion proceeds at a blinding pace. Therefore, it is important to carefully choose corrosion resistant materials.

Mud and grit pose a different set of problems. Fine dirt particles are small enough to easily get into tight spaces. They are very abrasive and can destroy moving parts and gaskets. Further, dirt particles are good insulators and can interfere with electrical contacts. The best method for preventing problems from mud and grit is to exclude them.

Hot and cold temperatures

High temperatures act to accelerate reactions and soften materials. This includes the rate of corrosion, the hardening of seals, the self-discharge rate of batteries and the evaporation of volatile agents in greases. The effects of high temperature tend to be permanent and are caused by premature aging.

Cold temperatures have a different affect. Cold temperatures act to slow down reactions and harden materials and make them brittle. Cold can also cause water to condense and freeze into a thin layer of ice, which can insulate switch contacts. Unlike the effects caused by high temperatures, the effects seen at extremely cold temperatures tend to be temporary and will reverse when the temperature returns to normal.

Hazardous atmospheres

Whenever the air around you contains potentially explosive gasses the light you are using must be explosion proof or intrinsically safe. This is to prevent a light from accidentally igniting the gasses and causing a fire or explosion.

The light must be designed in such a way that any two possible failures (such as a broken lens and a short circuit) cannot ignite an explosive atmosphere. Such failures are easy to imagine in harsh environments.

What the Action Light does for you

The Action Light is built from aircraft aluminum and is very rugged. The light is designed to take a lot of abuse without incurring any significant damage and to always stay in one piece. However, if the light impacts a hard surface with sufficient force you will cause damage that will need to be repaired. The light is designed to continue providing light even after sustaining substantial damage. The Low setting is designed to have the highest reliability so if you have a problem, always try the Low setting.

During testing, we subjected a test light to repeated 8 meter (26 foot) drops onto solid rock and one test with a calculated impact of 8000G's. That's equivalent to a 20 meter (65 foot) drop onto a hard surface. And the light continued to work on all settings. And yes, the light did end up with some significant dings. We should also point out that these impact loads far exceeded the battery manufacturer's limits and that the battery was damaged during the tests. However, the battery continued to function normally in spite of the damage inflicted.

All the electronics are hardened to enable them to stand the severe impact loads. Everything in the lamp is bolted down and then glued in place.

The Action Light is fully sealed against water and mud. Go ahead, use it for a dive light. We recommend you rinse the light after each dive with clean fresh water like you would do with any other piece of dive equipment. And you will need to periodically clean and grease the battery cap O-ring seal. The electronics bay is permanently sealed and the switch seals should not need service under normal use.

The lens is a special coated polycarbonate, which is one of the toughest plastics made. The special surface treatment provides 8 times the abrasion resistance when compared to regular polycarbonate using the Taber abrasion test. Using the same test, glass is an additional 8 times better still -- just in case you were wondering.

The Action Light is designed to be intrinsically safe, which means that the light is not capable of igniting an explosive atmosphere even if it is damaged and remains in operation. However, the Action Light requires use of a protected lithium battery to be considered intrinsically safe. Use of an unprotected lithium battery violates intrinsically safe design principles and will invalidate third party certifications.

Our standard finish is a black Type III hard anodize finish that complies with military specification MIL-A-8625. Hard anodize actually penetrates the aluminum surface structure and hardens it, making it very scratch resistant. It is still possible to dent the surface but the hard anodize will continue to adhere to the dented surface. The hard anodize is also resistant to most commonly encountered chemicals.

We also provide a wide range of colors in the softer Type II anodize for those folks that are more fashion conscious. Sorry, you can't have those brilliant colors and the superior scratch resistance at the same time. You will have to choose which is more important to you.

The Action Light is built tough to last you a lifetime.

Specifications are subject to change without notice.

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Updated February 2021