Shake-To-Charge Flashlights

Regardless of the brand name, the technology in the new shake-to-charge flashlights seems to be the same. The new shake-to-charge flashlights are based on simple electromagnetic induction through a unique dual-coil design to charge a high-capacity capacitor instead of a battery. Unlike a battery, the capacitor will never lose its ability to store a charge. Shake-to-charge flashlights use the Faraday Principle of Electromagnetic Energy to create the electricity they need to charge themselves. The Faraday Principle explains and examines how a magnetic field can produce electric current in a wire coil as it passes through. When a shake-to-charge flashlight is shaken, a magnet slides back and forth through a copper wire coil, by bouncing off a rubber pad at each end of the flashlight. The electricity produced as a result is then stored in a capacitor instead of a battery. A capacitor is a basic electronic component that stores electrical charge. A capacitor is used in the shake-to-charge flashlights instead of a battery because the power is always available by shaking the flashlight, thereby requiring less electricity storage than normal flashlights. An LED, or light emitting diode, is an electronic component that emits light when an electrical current is passed through it. LED’s, long used for electronic indicator lights, have become very popular for other lighting applications over the past few years in everything from street lights to roadway hazard lights and vehicles. A big reason for their popularity is their efficiency and lifespan. An LED is many times more efficient than a halogen or fluorescent bulb, and uses much less power.

If you’ve spent any time surfing for these shake-to-charge flashlights on the internet – you may have noticed a vast difference in price, as well as the claim of just how good these flashlights are. Like thousands of others, I was tempted by the television commercial to make a purchase, hoping the claim “the last flashlight you will ever buy” was true. I purchased the standard size model, the super size model, and received the pen light model as a free gift. Tucked inside each flashlight’s box was a small instruction sheet, and also the first discrepancy between the advertisement I’d made the purchased based upon and the actual product now in my hands. The television commercial touted “Shake for 30 seconds, flashlight lasts for up one full hour!” Untrue. The only time you can shake the flashlights for only 30 seconds and get light is when and if you have already charged them and are simply trying to maintain that charge. You must shake the super size flashlight model for a minimum of 3 full minutes to attain a full charge, the standard size flashlight and the pen size flashlight models for a minimum of two full minutes. The only way to maintain a charge for up to one full hour is to continue to shake the flashlights for 30 seconds in five minute intervals. Otherwise, all three flashlight models will completely lose their charge within ten minutes.

The next claim that seems less than authentic is “Flashlight beam visible for up to one mile!”. I’m not sure what test the manufacturers used to base this claim on, but in normal conditions outside of your home, the super size and standard size flashlights only provides adequate lighting within a 4 to 5 foot range. The pen light model only provides adequate lighting within a 2 to 3 foot range. One problem seems to be the clear (or slightly purple) plastic that the body of the flashlights are constructed from. The clear plastic allows for a great deal of “back lighting”, a significant amount of the light is wasted by emitting from the flashlight’s body instead of being focused to emit from the lens. The LED lamp is a good choice for any flashlight, it offers the high visibility blue or white light that greatly cuts down on glare and diffusion. The overall illumination capabilities of these flashlights could be greatly improved by manufacturing them with a solid color, non light emitting, body. This would enhance the LED’s reach by focusing all the available lighting through the lens of the flashlight.

The claim that the flashlights are water proof is also a bit deceptive. This is true of all the flashlight models except the pen light size. I have found some advertisements that claim the floating flashlight will also serve as a compass, with the flashlight beam always pointing toward the North. I have tried this with my flashlights and I can see how this claim could be made, the flashlights do tend to “tip” toward the North when floating. However, this really only works when the flashlight is completely still in the water. Any wave action or movement of the flashlight causes the light beam to tilt erratically in the water, with the beam shining in all directions. However, the claim that these flashlights are maintenance free, is true. None of the models contain owner serviceable parts, and any tampering with the flashlight’s seals will void any warranty the flashlights may have. The warranty seems to be at the discretion of the marketer. I have seen some as short as 30 days from the date of purchase, to full replacement warranties for the length of the original owner’s lifetime. In any case, I suggest you keep your receipt! In most cases you are not purchasing these shake-to-charge flashlights from the manufacturer, rather, a re-seller or marketer.

Overall these shake-to-charge flashlights fall a bit short of the fantastic marketing claims that sell them, but they actually are worth the purchase price as an emergency source of light. The fact they can be charged by the user, repeatedly, and for extended periods of time makes them a perfect addition to the automobile emergency kit, your boating tool kit, out buildings, garages, or anywhere emergency light might be required. If you make your purchased with the understanding that these shake-to-charge flashlights do not provide adequate lighting to perform brain surgery, and you will be shaking them vigorously for 30 seconds every five minutes, you won’t be disappointed.