Flashlights: Questions and Answers
Flashlights designed and built by Applied Innovative Technologies inspire people to ask a wide range of fascinating questions. Listed below are detailed answers to questions we've recieved through the years. If you have a question regarding our rechargeable LED flashlights please contact us and we'll post your question and our answer for others to learn from.
How do NightStar and LightStorm flashlights compare to one another?"
With only one moving part in the linear generator that converts mechanical energy into light, NightStar rechargeable LED flashlights have unsurpassed reliability. LightStorm flashlights use a high power brushless dynamo generator connected to a crank arm through a series of step-up gears. Unfortunately, as mechanical systems become more complex they inherently have more components that can potentially fail. The generator and gear system in LightStorm flashlights however, have been engineered to provide years of unfailing performance. In terms of durability, NightStar flashlights also have the edge because their polycarbonate (bulletproof glass) housings are nearly unbreakable, even in cold temperatures. LightStorm flashlight housings are constructed of ABS, which is tough but not nearly as strong as polycarbonate. NightStar flashlights also require only one hand to charge, LightStorm flashlights require two and are noisier. NightStar flashlights also feature glow in the dark switches, which allow them to be easily found and operated in dark environments. Finally, NightStar flashlights have been thoroughly tested by a variety of independent laboratories. LightStorm wind up torch lights on the other hand are significantly brighter because they incorporate a 1/2 watt Quasar LED which is powered by a 30 farad Carbon Ultra-Capacitor. The larger capacitor can be used in LightStorm flashlights because the dynamo generator produces far more energy then the linear generator used in NightStar flashlights. LightStorm flashlights also have more features than NightStar flashlights. For example, LightStorm CL1 has a spot light and flood light beam. LightStorm DL1 has a spot light beam and green flood light that can also be set to an emergency flashing mode. LightStorm SL1 has four different light settings; standard and super bright flood light, red flood light, and flashing red flood light. In addition, all LightStorm flashlights have a charging port for recharging cell phones and other electronic devices. Without a doubt however, owning a NightStar and LightStorm flashlight will prepare you for any situation where light is needed and both of these lights are unmatched in value because they will pay for themselves by never needing batteries or replacing.
"Can batteries be included in NightStar and LightStorm flashlights to allow for a longer, brighter light output?"
Batteries will power the LEDs in NightStar and LightStorm flashlights for several hours at maximum light output (the same light output obtained when a capacitor is fully charged and the light is first turned on). Additionally, the linear generator in NightStar flashlights and the dynamo generator in LightStorm flashlights can be used to charge batteries. However, the energy storage capability of a battery is many times greater than a capacitor. Consequently, it would require hours of shaking or cranking to recharge batteries using the charging systems in NightStar and LightStorm. Also, rechargeable batteiest have extremely short lifetimes when compared to capacitors. The Gold-Film capacitor used in NightStar flashlights and the Carbon Ultra-Capacitor used in LightStorm flashlights can be recharged over one hundred thousand times. Rechargeable batteries, such as NiCd, NiMH, and Li Ion, can only be charged and discharged several hundred times.* Batteries also fail to work effectively in cold environments; capacitors do not suffer this problem. Finally, batteries are both costly and considered a hazardous material. Batteries that depend on chemical reactions not only pose a danger to the environment but are also corrosive and can destroy a flashlight. Adding batteries to NightStar and LightStorm flashlights would therefore weaken their design and marketability. One of the most unique and significant features of NightStar and LightStorm flashlights is that they will never need parts or replacing. NightStar and LightStorm flashlights can be relied upon to light the way anytime, anywhere.
*The rated lifetime of these devices is determined by the number of cycles it takes to reach 80% of their rated energy storage capacity. The user will still get additional cycles after the rated life; however, the diminished storage capacity means less useful battery life.
"What is the shelf life of NightStar and LightStorm flashlights?"
The shelf life of every NightStar and LightStorm flashlight is limited to the capacitor – and the capacitor’s lifetime is driven primarily by the average storage temperature. In hot environments where the average year round temperature is 80ºF (27ºC), such as Phoenix , the capacitor will reach the 85% storage capacity point after approximately 19.7 years. By comparison, the capacitor will reach the same point after 78.8 years if subjected to the average year round temperature of 45ºF (7ºC) common to Minneapolis . In fact, the expected service life will double for every 10ºC reduction in temperature, as predicted by the Arrehenius Equation given by 2(70 – x)/10, where x is the average temperature in degrees Celsius . All other components should remain operational for considerably longer since they are either sealed within a polycarbonate or ABS housing and are only susceptible to possible degradation if subjected to prolonged temperatures above 176ºF (80ºC). Of course, these expected lifetime values are theoretical (though values used in the equations are based on manufacturer’s component test data). What can be said with absolute certainty is that the first NightStar flashlights were built and sold over 12 years ago and since then only a handful have been replaced due to component failure, and most of these were failures due to broken reed switches (possibly resulting from severe abuse).
"Can light output of NightStar be made brighter by replacing the StarCore LED with an incandescent bulb?"
An incandescent bulb is highly inefficient and requires significantly more energy than a StarCore® LED. The capacitor in NightStar can only power a filament light bulb for several seconds but can power an LED for more than 20 minutes. An incandescent bulb also has a lifetime of approximately 500 hours and is extremely fragile. Quite frequently, a bulb will break before it burns out. By comparison, the StarCore LED used in NightStar will operate for more than 50,000 hours and is nearly unbreakable. Therefore, for reasons of energy efficiency and reliability, a StarCore LED is the logical choice for the entire family of NightStar LED flashlights.
"Can adding more LEDs increase the light output of NightStar flashlights?"
The ETS (Energy Transformation System) Cell within the NightStar flashlight can power more than one LED, and with each LED added, the light output will increase. However, power consumption will also increase with each LED added to the system. Consequently, the duration of light output obtained from a fully charged capacitor will diminish, thereby requiring the flashlight to be shaken more frequently. Adding more LEDs will also increase the cost of the device. Therefore, one StarCore LED was chosen in order to maximize the time between recharge cycles and to minimize the unit cost.
"Why is NightStar 3 brighter than NightStar CS2 ?"
The difference in brightness between NightStar 3 and NightStar CS2 has to do with beam divergence. NightStar 3 has a more collimated beam, and therefore more concentrated. The reason for this is that the distance from the LED to the lens is greater in NightStar 3 than CS2. In NightStar 3 the distance is approximately 0.70" (which is very close to the separation required to obtain a collimated beam). In NightStar CS2 the distance is only 0.55". Consequently, at a distance of 10 feet (3 meters) the beam divergence of NightStar 3 produces a 2.5 foot (0.76 meter) diameter field of illumination whereas the beam divergence of NightStar CS2 produces a 1 meter diameter field of illumination. In terms of overall light output from the LED however, the two lights are nearly the same because their circuitry is identical.
"Regarding "Peak Brightness", what is the definition of lux and lumen?"
The difference between lux and lumen is that lux takes into account the area over which the luminous flux is spread. One lux (illumination) is equal to one lumen per square meter: 1 lux = 1 lumen / square meter. For example, a flux of 1000 lumens, concentrated into an area of one square meter, lights up that square meter with an illuminance of 1000 lux. The same 1000 lumens, spread out over ten square meters, produces a dimmer illuminance of only 100 lux. In the case of NightStar 3 and CS2 the light output was measured directly in front of the lens where the illuminance is greatest. At maximum or "Peak Brightness" the illuminance for NightStar 3 is 16,000 lux which is contained within a .0008 square meter area. By rearranging the equation above we can determine the corresponding lumen output of the light; we therefore have 16,000 x .0008 = 12.8 lumens. In the case of CS2 which has a lux of 9500 contained within a .0007 square meter area, the corresponding lumen output is 6.7. At a distance of 3 meters from each light, the illuminance (or lux) for NightStar 3 (where the beam diameter is 0.76 meters) is equal to: 12.8 / (pi x [(0.76/2) x (0.76/2)]) = 12.8 / 0.45 = 28 lux and for NightStar CS2 (where the beam diameter is 1.0 meters) the illuminance is equal to: 6.7 / (pi x [(1.0/2) x (1.0/2)]) = 6.7 / 0.79 = 8.5 lux. As one can see, the illuminance drops off quickly with distance. By comparison, the illuminance of NightStar 3 and NightStar CS2 (at a distance of 3 meters) are 28 and 8.5 times brighter (respectively) than the illuminance produced by the full moon (which is 1 lux). To really put things into perspective, the peak brightness of the sun as seen on the earth is 25,000 lux!
"How is the charging magnet reflected at either end of the NightStar flashlight?"
Neodymium magnets are mounted at both ends of the flashlight and are oriented to repel the charging magnet. The magnetic repulsion recoil system smoothly decelerates and accelerates the charging magnet back through the coil without loss in mechanical energy. Consequently, the loss of energy due to friction is extremely small and is only the result of the cylindrically shaped nickel-plated charging magnet sliding through a polished tube. Kinetic energy is therefore efficiently coupled into electrical energy with almost no degradation to the system. Lasting performance is obtained with this design.
"Why do NightStar 3 and NightStar CS2 require different amounts of shaking?"
First of all, NightStar 3 rechargeable torch and NightStar CS2 rechargeable LED flashlight both use a 1.5 farad capacitor. The time it takes to recharge the capacitor is dependent upon the amount of electrical energy produced with each passing of the charging magnet through the coil. Because NightStar 3 uses a much larger magnet, the magnet field line density is far greater. Coupled with this is that NightStar 3 has a much larger coil, which has a larger cross sectional area and more windings. Because of the longer throw distance in NightStar 3, the magnet can travel faster as it passes through the coil; ultimately, the energy pulse generated as the magnet goes through the coil in NightStar is greater than in CS2 or RS, and is proportional to (N)(A)(B)(v), where N is the number of coil windings, A is the cross section area of the coil, B is the magnetic field strength, and v is the velocity of the magnet. As you can see, the capacitor in NightStar 3 will charge more quickly then the capacitor in NightStar CS2 or RS.
"What are the magnets made of in NightStar flashlights and how are they magnetized?"
The magnet is an anisotropic sintered ceramic containing neodymium, iron and boron (NdFeB). The anisotropic nature of the material (meaning that it has properties that differ according to the direction of the measurement) is due to the tetragonal crystalline structure of the NdFeB molecule. The magnetic dipole associated with each crystal lattice site aligns itself along a well-defined axis within the bulk material. As a consequence of its molecular magnetic structure, the material is remarkable in two ways: First, it possesses a high-density magnetic field because of the alignment uniformity of the magnetic dipoles; and second, it will hold this field for an extremely long time even when oriented for repulsion with another magnet or subjected to extreme temperatures. All of the magnets in NightStar are initially slugs or disks of ceramic NdFeB. They are then plated with either nickel (the charging magnet and the switch activation magnet) or zinc (the repulsion magnets mounted on either end of the light). The plating, which gives the magnets a metallic look, serves to protect the magnet from corrosion, chipping and scratching. Nickel is a standard, tough, smooth coating and zinc protects the magnet and provides an excellent bonding surface. Finally, the coated ceramic pieces are placed in a toroid chamber that converts electricity into an extremely high strength magnetic field. The ceramic pieces become magnetized within a few seconds and will remain so for thousands of years.
"Why is the NightStar flashlight housing made from plastic?"
Most importantly, any type of metallic housing will prevent the charging magnet from moving effectively through the coil. This is due to free electron eddy currents being set up in the metal housing when the charging magnet travels through the barrel. Consequently, magnetic fields generated by the eddy currents in the housing oppose the magnetic field of the charging magnet. The faster the charging magnet tries to move, the stronger the opposing fields will be in the housing. Therefore, the charging magnet will never pass through the coil with enough speed to charge the energy storage capacitor. The plastic housing is superior to a metal housing in several other ways as well. The material and manufacturing costs of plastic are far less expensive then aluminum (aluminum is a likely choice for a metal housing). Additionally, NightStar's plastic housing will never rust or oxidize and weighs less then an aluminum housing that would provide the same amount of crush resistance. The plastic used in the stealth black NightStar red and green LED flashlights is an alloy of polycarbonate and ABS. The transparent housings of NightStar 3 and NightStar CS2 however, are made of pure polycarbonate because polycarbonate/ABS is not available in clear). Polycarbonate/ABS was chosen for two reasons: First, it is difficult to break even at cold temperatures; and second, it is unaffected by salt water, mild acids, alcohol, methanol, and ammonia based cleaners and is corrosion resistant when briefly exposed to petroleum products such as gasoline, oil and grease. Clear NightStars are not as chemical-resistant against petroleum products but have slightly higher impact strength.
"Why was a lens chosen for the output window in NightStar?"
Placing a specially designed acrylic lens at the appropriate point effectively collects and images the light output from the LED. The lens also serves as a window, and due to its design it is able to withstand tremendous pressure, shock and hazardous chemical environments. Therefore, with a single component, optimum light output and durability is obtained.
"Why doesn't the beam from NightStar flashlights interfere with night vision?"
NightStar doesn't affect your night vision because it isn't overwhelmingly bright. If you're using a Maglite for example, and you're looking at the area illuminated by its beam, your eye's natural tendency is to aperture down to obtain a comfortable light level. If you now look away from the beam, everything looks dark and will remain so until the eye's iris dilates to allow more light in. With NightStar, the iris remains open to the point where objects outside the beam are still visible. This is one of the reasons the military prefers NightStar for extended night time operations.
"Can NightStar's beam penetrate through smoke?"
Experiments conducted in the "Zero Visibility Smoke Chamber" at the firefighting training and test facility in Loveland, Colorado demonstrated that NightStar's blue-white beam, though not useful as an illumination source, is quite effective as an emergency signaling light and can be seen through smoke over 20 feet away. By comparison, the high power lights typically used by firefighters penetrate only a few feet through smoke while simultaneously back scattering off the smoke particles and blinding the searcher. NightStar's beam appears as a blue-white shaft of light that extends out 3 to 4 feet from the searcher and has no blinding backscatter problems. (All tests were made possible by the tremendous support of the Loveland Fire Department. Smoke in the chamber was produced by burning hay and couch fabric material.)
"Is a pacemaker sensitive to the magnetic field that surrounds the NightStar flashlight?"
NightStar can affect a pacemaker's normal mode of operation. If the heart rate of a person with a pacemaker drops below a preset value (typically 85 beats per minute), an internal sensor monitoring the person's heart rate activates the pacemaker. A pacemaker will not send electrical signals to a person's heart unless their heart rate drops below the preset value. In order to test whether a pacemaker is operating properly, a Reed switch is built into the unit so that an external magnet held up to the patient's chest will close the Reed switch and deactivate the internal heart rate sensor. When this happens, the pacemaker turns on and begins sending electrical signals to the heart at the preset value. Pacemakers are typically tested once or twice per year in specially equipped hospitals. If a pacemaker begins sending signals to the heart at a rate of 85 beats per minute and the heart is already beating at a greater rate, an arrhythmia condition can be triggered. The possibility of this occurring is extremely rare; less than 1 percent of the people with pacemakers would be susceptible to this condition, and in many cases these susceptible people are already bedridden. A magnetic field with a strength of 90 gauss brought within 1.5 inches (40 cm) of a pacemaker will close the Reed switch. The magnet in NightStar has a surface field strength of over 5200 gauss. Consequently, in order to avoid turning on a pacemaker, NightStar should be held no closer than 2 inches (5 cm) to the chest. At this distance the field strength has dropped to approximately 30 gauss. A cautionary statement regarding the effect NightStar has on pacemakers is printed on the product packaging.
(This information was obtained from a telephone conversation with one of the largest manufacturers of pacemakers in the United States).
Who Invented the Shake Flashlight?"
NightStar is the world's first renewable energy shake flashlight. Invented in 1997 by Steve Vetorino, co-founder of Applied Innovative Technologies Inc. Jim Platt and Doug Springer; it first entered production in 1998. The NightStar flashlight was issued its first patent in 1999 (Patent #5,975,714). In 2001 it was issued its second patent (Patent #6,220,719) for the magnetic recoil charging system. Using magnetic repulsion to rebound the charging magnet is far more efficient and quieter than springs. In 2004 it was issued its third patent for the reflector and lens optical system that effectively collects and projects a uniform beam of light.
