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Most of us have had the annoying experience of the bulb failing in our flashlight, usually at a less than opportune moment. Even when there's a spare handy, changing it can be a challenge in the dark. How appealing would you find a flashlight with a bulb that never burns out, or at least not for tens of thousands of hours?
Then there's battery life, or lack thereof. If the bulb isn't failing, the batteries are petering out. The light dims and is extinguished just about the time you need it the most. Changing batteries in the dark, even when you have them, is usually a trial. How appealing would you find a flashlight whose batteries last tens of hours, or even hundreds of hours?
We're talking about flashlights that use LEDs (Light
Emitting Diodes) instead of conventional incandescent bulbs. Yes, these are the
same LEDs you've seen in electronic equipment, digital signs, cheap key ring
lights, and the like for years. The
problem has been that while LEDs came in an array of colors, they didn't come
in white--until very recently. Other
colors might suffice to light up a keyhole or to read a chart without
diminishing your night vision, but for general practical use they left a good
deal to be desired. Some have tried using a mixture of primary colors, with
varying effectiveness, but that's not exactly an elegant solution.
In the early 1990s Shuji Nakamura of Nichia Chemical (now Nichia America) developed the first viable white LED (Read: about his significant accomplishments in this a related fields as well as a fascinating interview about his battles to develop this and other ground breaking devices in a Scientific American interview). Actually, the term “white LED” is not technically correct. The LED itself generates blue light, but a micro-thin coating fluoresces when struck by the blue light, generating a white light.
In part because of this two-stage process, initial examples were pretty dim. They were also very expensive, as with most newly developed technologies. Recently they have been getting brighter and brighter and, if not inexpensive, at least much more affordable. While still far dimmer than other LEDs of comparable size and energy use, they are bright enough to make a white LED flashlight practical, at least for some uses. Brightness is also a function of the beam angle built into the LED's integral reflector. The advent of narrow angle (20 degrees) LEDs has also made a big difference in usability.
Not all white LEDs are equal. When they produce LEDs, and especially
white LEDs, there is considerable variability among them, both in terms of
brightness and the actual color, a problem that was at times very evident in
our tests. Like pearls, LEDs are graded and can be matched, in this case for
output and color. One fallout from this has been that the brighter and whiter
you want them, and the better color matched they are if more than one, the more
expensive these LEDs are. That
translates to a more expensive end product.
In any case, the bluish white color is far different than
that from a typical incandescent bulb. No matter what type incandescent it is,
there is a yellow cast to the color, to one degree or another. The white LEDs'
color is far closer to that of natural sunlight, thus colors are rendered more
naturally. However, some find this color “unnatural” since it's so different
from what they are used to from a conventional bulb. It can take a while to get
comfortable with the color.
We collected all such white LED flashlights we could find for our review. Developments and new entrants into this market are coming so fast, it's difficult to keep up, so inevitably we're going to be a bit behind the power curve for a while.
There are numerous single-LED "key chain" style lights available that operate only via a momentary switch, they do not have a constant on mode. We feel that constant on mode operation is an essential element for any flashlight, so we have not reviewed any new lights which do not have this feature.
NOTE: If you manufacture or distribute an LED flashlight we haven't covered here, please email us and we'll make arrangements to evaluate your light(s) to add to this review.
Some of these lights claim to be waterproof or
water-resistant. However, with the exception of one manufacturer's product line, these
are not truly waterproof in the same sense as we think of a dive light being
waterproof. (Actually, the proper
technical term is “submergible” for which there are accepted standards and
tests.) For the most part these lights
don't claim to be waterproof--if you read the fine print. We tested the lights claiming to be
waterproof by submerging them for a few days in four feet of water and all
passed that moderate test. Those
claiming to be water-resistant, we submerged in the sink for five minutes. All did just fine. We then tested the water resistant lights in the pool as
well. Only a few, as noted, continued
working.
Many of the water resistant lights function even though they were flooded inside and drying them out after getting wet is all that is needed to maintain their usefulness. Failing to do so results in a rusty mess that sooner or later quits functioning.
Shock resistance is another advantage claimed for LEDs. We drop tested the flashlights four times from six feet onto concrete with not a single LED failure and little in the way of any other visible damage to the body of the lights themselves. That's an impressive showing.
In some instances with tubular design flashlights with multiple AA-cell or larger batteries we had some functional failures. This occurred intermittently and only when dropped squarely on the head or tail. The weight of the batteries combined with the force of impact deformed the positive terminal (the "nipple"), forcing it down into the body of the flashlight. When this occurs, either contact is lost between the batteries or internally there is some sort of damage, either of which can prevent electricity from flowing. This is no different that what can happen with a conventional flashlight of similar design.
While some makers claim the LEDs will last upwards of 100,000 hours, others only claim 50,000. Experts tell us that LED life may vary considerably depending upon how they are powered and what voltage is used. Many of these lights are pushing more volts through them than the LEDs were originally designed for in an effort to increase light output. Even so, you should expect the LEDs to last, as we noted above, tens of thousands of hours, even when over-powered to a degree. They can be burned out if too much power is applied, but none of the lights we tested exhibited that problem.
Another significant advantage of LED flashlights, as noted
above, is that battery life is extended far beyond anything we have come to
expect, though in our tests actual results varied from manufacturer's claims,
both plus and minus. With no real standards
for measuring battery life with this new technology, all claims must be taken
with a grain of salt. Moreover, you are rarely comparing apples to apples as
light output is also often much less than typical incandescent bulb
flashlights.
As the battery charge declines below nominal, the LED doesn't go out, it simply gets dimmer. In many cases this residual illumination will last again as long or longer than the nominal light output and the flashlight may still be useable for many chores at these reduced light levels. In many cases battery life overall can be measured in days, not hours.
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 “visible 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.
 ETS is pleased to collaborate with Craig Johnson on LED matters. His LED Museum offers additional LED flashlight reviews, technical data, and photos; as well as a slightly different perspective.
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NOTE: Prices are suggested retail as of May 2001 for comparison purposes only. Many, but not all, of these lights are available at discount.
NOTE: Information on country of manufacture was provided by the manufacturer and covers primary components only. Many of the smaller components in products, such as screws and electronic bits and pieces of larger electronic components, are made in low cost of production countries and then assembled elsewhere and it would be unwieldy to list all these small parts. Nor do we list separately common components such as batteries that are almost always made in low cost of production countries. Only significant component part(s) manufactured elsewhere than the country of manufacture are listed separately.
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LED Flashlight Review (click to continue to next page) or Select link below |
ManufacturersLightwave Company (Lightwave 2000)
Conclusions – Multi-LED Flashlights
Conclusions – Single-LED Flashlights
Additional LED Flashlight Information:
(LED flashlight reviews by Craig Johnson with whom ETS collaborates on LED matters.)
(Brock Neverman's page provides addtional LED flashlight reviews, information and photos.)
(Discussion of LED flashlights, from the frivolous and inane to technical and astute.)
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Publisher and Editor: Doug Ritter
Email: Doug Ritter
URL:
http://www.equipped.org/led_lights.htm
First Published: June 7, 2001
Revision: 04 June 21, 2001
Email to: info@pulvertech.com
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