When people find out that technology has progressed to the point at which we no longer need to recharge batteries for particular flashlights and that some can be charged with a simple couple of shakes, they are almost always floored with surprise. The entire process that allows this to be possible is surprisingly simple to understand. Flashlights, by design, require very few parts to function. When aligned correctly, the basic components produce portable, sustainable artificial light. In order to construct a flashlight that can be shaken to be charged, all that is needed are rare earth magnets, capacitors, wire coils, and light bulbs placed and pieced together in an incredibly deliberate, correct way.
When a magnet is passed through a coil of wire, an electrical current, albeit small, is generated. In this type of flashlight, the current is stored in the part called the capacitor and is used almost like a battery to power the light bulb.
When the flashlight is shaken, the magnet moves vertically along wire coil inside the length of the flashlight. The capacitor is lined up with the light bulb in order to provide it power.
Quality of an item such as this depends almost solely on the quality of the components that put it together. A magnet with a higher power and a coil with a higher amount of wire will generate more electricity naturally, making the flashlight charge to full power more quickly, and similarly, a bigger capacitor stores more power, and a bulb that uses less energy will stay brighter longer.
Because magnets are a key component in the creation of the flashlights, the most powerful of all magnets, rare earth magnets, are used. As one might be able to tell from the name, these rare magnets are made of alloys from more rare elements. They are the strongest magnets available, period.
The thickness of a wire coil has no real value in comparison to the amount of times the wire goes around. More windings means more surface area and a greater time frame for the magnet to generate more and more power.
The greater the size of the capacitor, the longer the flashlight can stay lit at a time. The variables that effect the storage capacity are physical size and quality.
Nearly all flashlights that can be shaken to recharge them require LED light bulbs. These bulbs produce a higher amount of light for a far lesser amount of energy in comparison to other more traditional light bulbs. This translates to not draining the capacitor as quickly for sustained energy.
Although a flashlight that needs no batteries seems complicated, in actuality, as is apparent, it is not. All that is truly necessary to create a great flashlight are rare earth magnets, capacitors, wire coils, and LED bulbs.
