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The LED-Lenser (Coast) David 15 is an aluminum bodied,
single high-output-LED light, which is powered by one
AA cell and a built-in boost circuit. It has a clickie
switch on the tailcap and is available in matte silver,
blue, or black finish colors. Internally, gold plated
contacts are used to improve electrical conductivity.
Now I hope no one takes this the wrong way, but LED-Lenser
uses the most imaginative language when describing their
products. In some cases, these terms need translation
to to the common terms we all use. Here's some examples
of their terminology and the generally equivalent common
terms:
"Light Chip" = LED, generally this seems
to refer to 5mm LEDs
"Digital Power Light Chip (DPLC)" = LED,
generally seems to refer to 1 Watt or greater
"computer calculated lens" or "strongly
focusing axial collimator" or "Light Centering
Collimator (LCC)" = collimator lens
"eco-friendly Nickel-hybrid accumulator"
= NiMH rechargeable battery
"Power Transformer Technology" = boost circuit
In an attempt to market products, companies sometimes
use new terms to describe the features their product
has in order to distinguish them from those same features
(and benefits) that the competition has. I've had several
people ask me enthusiastically about the apparently
new technology LED-Lenser uses (an assumption based
on the new terminology) only to be very disappointed
when I explained that the folks at LED-Lenser had not
come up with some magical new technology that was vastly
different from all the rest. They still use LEDs, collimator
lenses, and sometimes boost circuits or regulator circuits
to produce light.
Body: The body of the David 15 is aluminum with
a diamond checker pattern around the center of the body
tube and around the tailcap. There are 8 holes around
the front end of the light, an LED-Lenser trademark,
which allow light to bleed out to the sides. This serves
as an indicator that the light is on when it is placed
face down on a flat surface. The clickie is on the removable
tailcap which has a tab and a ring for the attachment
of a lanyard. Overall construction and machining is
very good, demonstrating precise technique and good
quality control.
Bezel/Head: The front of the light contains
a very concave collimator lens. I was surprised by the
fact that the polycarbonate collimator was not protected
by an outer window. A drop in the mud will fill this
rather large space with muck which will need to be washed
out, not just wiped off. Surrounding the lens is a cylinder
of blue plastic which helps seal the holes around the
head and gives the light filtering through the holes
a bluish tint. Behind the lens is the high output LED
and boost circuit designed to increase the voltage from
a single AA cell to levels which will power the LED.
Output: Output is in the form of a rather tight
beam of white light with a bright central spot, square
corona, and round spillbeam. No significant tinting
can be seen in most of the beam of the sample tested.
I did note that at a projection distance of about 12
inches, one corner of the square corona has a blue tint.
Remember that some variability in LED tinting is always
possible. This is just the nature of LEDs.
The David 15 does produce a good volume of light for
its size and power source.
Beam at one meter at target center
Runtime Plot: Unfortunately, it looks like it
is a straight boost circuit being used in this light,
as light output is not well maintained at all. Output
declines over time in a manner similar to a light being
driven directly by batteries with no regulation circuit
at all. This was a bit disappointing to me. On the good
side, you do get well over 2 hours of bright output
followed by a long tail of diminishing light, so you
don't have to worry about the light just "going
out" when you need it.
Runtime
completed with LEDLenser brand batteries. More information
on runtime plots is available HERE.
Switch: The switch is advertised as water resistant
and consists of a metal clickie on the tailcap. It is
machined and fitted in such a way to protrude slightly
above the contour of the rest of the tailcap. Press
gently to blink, press until it clicks for constant-on,
press again until it clicks for off.
I was able to click the switch on and off by pressing
the tail of the unit against a flat surface, so there
is a definite possibility of accidental activation when
packed. Remove the battery when you are packing it for
travel.
Seals / Water Resistance: "Water resistant"
is the way the David 15 is advertised. It has O-rings
at both ends, but I'm not sure about the clickie switch
or the area around the lens. I'd say it's "splashable"
at the least. If it gets wet inside, just disassemble
it as much as is possible without tools and let it dry
before next use.
Ergonomics: It's small, lightweight, easy to
use, and the switch operates without any problems. The
switch is fairly small, so I'm not sure how easy it
would be to operate the switch if the user had big hands.
Size compared to a common 2AA aluminum light
Batteries: A single alkaline AA cell powers
the light for many hours. To change out the cell simply
remove the tailcap, drop out the old cell, put in a
new cell positive first, and reattach the tailcap. You
should be ready to go.
Accessories: Included with the light is a very
nice nylon belt sheath, a carbiner to clip it anywhere,
and a wrist lanyard.
What I Liked: Good output and runtime,
good general construction and machining.
What I Didn't Like: No protective
lens window in front of the deep collimator lens. Not
truly regulated.
Picky Little Things: Strange blue
tint in only one little part of the beam. No way to
lock-out the switch to prevent accidental activation
during packing.
Conclusions: Well, in general I'd
give it a "Thumbs Up". It produces good output
for a reasonable amount of time. Construction is much
better than you would generally find for a flashlight
and its design appears to be fairly well thought out.
It throws a good spot for such a small light, and the
fact that it runs on just one AA cell is a great bonus.
Even if you can only find one good cell, you'll have
light.
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