Power Sources Of Flashlights
A flashlight is a portable hand-held, battery-operated light used for illumination. Flashlight performance mainly depends upon the power sources of the flashlight i.e., the performance of the battery. Picking the right battery can reduce the cost of operating the flashlight. You can find more about flashlights powered by AAA, AA and 18650 batteries at http://tacticalflashlightexpert.com/best-18650-flashlights/. On the simplest side batteries are like tissues — useful and disposable. But on the other side if you want to see its performance, you need to understand a bit more about these magical, portable power cells. The choice of batteries plays a determining role in the size, weight, run time, and shape of the flashlight. Mainly two types of batteries are used: primary and secondary. Primary battery types are disposable and secondary types are rechargeable battery types.
Primary battery types include button cells, carbon- zinc batteries in both regular and heavy duty types, alkaline and lithium. These are most economical batteries for infrequent use. Regular battery types are cheap and battery of choice for general purpose flashlights. Heavy duty type batteries are heavy and with smaller lights offering similar performance. Lithium battery cells can be stored for years with less risk of leakage as compared to zinc type batteries and moreover these are the primary batteries useful at lower temperatures. Lithium batteries have water- base electrolytes and lithium has lower internal resistance than zinc and so more effective in high drain flashlights. These are the battery of choice for tactical lights because these batteries have two times voltage of alkaline batteries and about half the size.
Flashlights used for extended periods may be more economically operated on rechargeable (secondary) batteries. They use proprietary battery packs, but some of these can also use regular batteries. Rechargeable flashlights are popular among law enforcement and professionals because they can save hundreds of dollars in purchasing disposable batteries. There are several types of rechargeable battery chemistries. Each of them has its own advantages and disadvantages. These include Nickel-Cadmium (NiCd, Typical Life: 1,000 cycles), Nickel-Metal Hydride (NiMH, Typical Life: 1,000+ cycles), Lithium-Ion (Li-Ion, Typical Life: 500 cycles), and Capacitor (Typical Life: 50,000 cycles).
NiCd batteries have been used for many decades and are more robust but less energy dense than newer batteries. NiMH batteries are more energy-dense and provide more runtime as compared to NiCd. Stored NiMH batteries need to be recharged periodically to ensure that the light is ready to use, unless they are marketed as “low self-discharge”. Li-Ion batteries are smaller, lighter, and are more powerful than NiCd and NiMH. These batteries are ideal for use in laptops and portable electronics. Capacitors are new under the category of power sources of flashlights. These are lightweight and can be charged rapidly. They cannot hold as much power as traditional batteries and will discharge within weeks.
Alternate power source of flashlights other than batteries can be mechanically drawn. It consists of a winding crank and spring connected to small electrical generator. Some use the dynamo or light to charge the capacitor while others generate electricity using electromagnetic induction. It can be used during emergencies, when utility power and batteries may not be available.
In short, batteries are the power plant of any lighting system without which no flashlights can be generated.