NightStar Flashlights: Questions and Answers
Since the global introduction in 1997 of shake flashlight technology by Applied Innovative Technologies, people have asked a wide range of fascinating questions. We appreciate the questions and welcome the opportunity to share our answers. If you have a question regarding our rechargeable LED flashlights please contact us so we can post your question and our answer for others to see.
Who invented the first commercially available Shake Flashlight?
Answer – Applied Innovative Technologies, Inc. NightStar is the world’s first commercially available renewable energy shake flashlight. Invented in 1997 by Steve Vetorino, Jim Platt and Doug Springer; the flashlight first entered production in 1998. 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.
Over the years AIT has discovered numerous companies claiming technology ownership. To that we say imitation is the ultimate form of flattery!
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 than the linear generator used in NightStar flashlights. LightStorm flashlights also have more features than NightStar flashlights. LightStorm SL1 has four different light settings; standard and bright flood light, red flood light, and flashing red flood light. In addition, LightStorm SL1 has a 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 lights are unmatched in value because they will pay for themselves by never needing batteries.
“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 SL1 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 batteries have extremely short lifetimes when compared to capacitors. The Gold-Film capacitor used in NightStar flashlights and the Carbon Ultra-Capacitor used in LightStorm 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 costly and considered a hazardous material. Batteries that depend on chemical reactions not only pose a danger to the environment but are corrosive and can destroy a flashlight. Adding batteries to NightStar and LightStorm flashlights would therefore weaken their design. One of the most unique and significant features of NightStar and LightStorm flashlights is they will never need parts. NightStar and LightStorm flashlights can be relied upon to light the way every time, 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, Arizona 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, Minnesota. In fact, the expected service life will double for every 10ºC reduction in temperature, as predicted by the Arrhenius 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 the first NightStar flashlights were built and sold in 1998 and continue to shine.
“Can light output of NightStar be made brighter by replacing the LED with an incandescent bulb?”
An incandescent bulb is highly inefficient and requires significantly more energy than a 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 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 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 LED was chosen in order to maximize the time between recharge cycles and to minimize the unit cost.
“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 a luminance of 1000 lux. The same 1000 lumens, spread out over ten square meters, produces a dimmer luminance of only 100 lux. In the case of NightStar the light output was measured directly in front of the lens where the luminance is greatest. At maximum or “Peak Brightness” the luminance for NightStar 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. At a distance of 3 meters, the luminance (or lux) for NightStar (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. As one can see, the luminance drops off quickly with distance. By comparison, the luminance of NightStar is 28 times brighter (respectively) than the luminance produced by the full moon (which is 1 lux). To really put things into perspective, the peak brightness of the sun as seen on 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.
“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 than an aluminum housing that would provide the same amount of crush resistance. The plastic used in the stealth black NightStar LED flashlights is an alloy of polycarbonate and ABS. The transparent housings of NightStar JP 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 NightStar is 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 high intensity light 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.
“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 pre-set 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 pre-set 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 measuring 90 gauss brought within 1.5 inches (40 cm) of a pacemaker will close the Reed switch. The magnet in NightStar surface field strength is 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).