When investigating modern flashlight technology, advances in bulbs and design are indeed revolutionary, but the most fundamental aspect of the flashlight, the power source, has also enjoyed the most remarkable change in design. Indeed, in the beginning of flashlight history was defined by the challenging aspect of reliable power. The initial flashlights used non-efficient carbon-filament type bulbs, “resting” was essential at short intervals. The name, flashlight, is in existence because, although a life-saving piece of equipment, the first design could only sustain its illumination in sporadic intervals… leading to the nickname highlighting a temporal ‘flash’ of light.
Modern incantations of the flashlight are indeed often defined by their power source, or their batteries in most cases. Batteries provide a consistent, reliable, and an increasingly environmentally efficient power source for the modern flashlight. Modern flashlights vary in numerous ways shapes and sizes, and this is also true of their batteries. Separated into two main types, primary and secondary, or disposable and rechargeable respectively – with many different kinds in between them, flashlights use both types.
The battery is the most common source of power for flashlights. Types of batteries include: button cells, lithium batteries, alkaline, and rechargeable nickel cadmium, NiMH, and lithium ion varieties. Battery choice depends on the particular light source needed and the desired size of the flashlight.
Disposable batteries, either alkaline or lithium, have extended storage life, 7 to 10 years approximately, but the inefficiency of disposable batteries makes them undesirable for prolonged usage and disposal of spent battery casings is incredibly toxic to the environment. Disposable batteries are known for longer run-times for particular bulb strength and are typically lower in initial cost and easy to store when back ups are needed. Their overall usage cost is much higher compared with re-chargeable batteries, and not as bright as Lithium batteries. Lithium Batteries were created for higher energy output, although more expensive.
Rechargeable flashlights come in two forms. Nickel cadmium is a durable, rechargeable choice providing the most impressive performance to cost ratio. Lithium-ion batteries, known for their light weight and supremely low operating expense and are perfectly suited for frequent use. Both can support a brighter bulb or LED utilizing charger holders. Their preliminary investment is relatively expensive and can be prone to release energy at an increased degree while in free storage.
Flashlights are solar powered, using the energy generated from a solar cell to charge an on-board battery for later use.
Mechanically powered flashlights have become increasingly popular. Flashlights built with a winding crank connected to a conveniently sized electrical generator powered by a capacitor. Some newer flashlights utilize electromagnetic induction. These flashlights use a heavy-duty permanent magnet that can loosely slides up and down in a cylinder, passing through a coiled wire as it moves. Shaking the flashlight will charge a capacitor or a rechargeable battery that supplies a current to a light source. Such flashlights can be most used as backup during an emergency, not ideal for high beam prolonged use.
