We arbitrarily defined battery life as the point at which light output was noticeably dimmer and full original functionality diminished.?Most of these white LED lights have a brief initial period of greater brightness after which the light settles down to a slightly lower level of illumination that will continue for some time. Also, in normal use, where flashlights are generally used intermittently, battery life may be longer because batteries are at their worst when current draw is continuous.

On a related note, battery price and availability can be an issue worthy of consideration, depending upon your use and where you reside or plan to travel. Conventional alkaline AAA-, AA-, C-, and D-cell batteries are easy to find almost anywhere and are inexpensive. An unusual size, such as an AAAA-cell alkaline battery or 3.6 volt AA-cell size lithium battery can be very hard to find and expensive to boot, often over $10 each. In the middle range are coin and button cell lithium batteries, often used in watches, hearing aids and similar devices, that are fairly widely available, even in non-specialty stores, and the cost, while not cheap, is not outrageous.

Lithium batteries generally offer more power for a comparable package size. This may be greater voltage or longer life or a combination. Lithium batteries also have a much longer shelf life than alkaline batteries, up to 10 years with 90% to 95% capacity, or better, retained. A conservative storage life for undated lithium batteries would be 6 years. Expect only 4 to 5 years from alkaline batteries with a conservative storage life for undated batteries of 2 to 3 years. Lithium batteries also deliver far better cold weather performance. An added benefit is that they are much lighter than alkalines by over one third for a comparable size. For example, an AA-cell lithium weighs in at 14.5g vs. 23g for an AA-cell alkaline.

The flashlights we tested ranged from single LED lights to a 24-LED Flashlight.?Even the brightest won't punch a beam out as far as a bright, well-focused halogen or xenon beam from a conventional incandescent flashlight, regardless of size.?That hasn't prevented some from claiming they are isible for over a mile,?which isn't a false statement, just a bit misleading if you don't read carefully.? That someone can see the light a mile away doesn't mean you can illuminate anything a mile away, a different thing altogether.

However, for many uses, bright, tightly focused beams are counterproductive and the best of these lights provide excellent quality, diffused light, along with generally exceptionally long battery life and those nearly indestructible "bulbs."? One flashlight we tested doesn't even require batteries.?

Size also varied a great deal, from diminutive lights smaller than a quarter using miniature lithium cells to lights the size of a conventional three D-cell flashlight. Smaller lights designed for pocket carry need to be really small to be functional, in our opinion.?Few people care for a big bulge in their pocket, it's uncomfortable and unsightly. Larger lights had best provide enough added performance to warrant the extra bulk and weight.

The news come from www.bossgoo.com

LED lights           LED Flashlight