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The AL-91AA 5mm Nichia Pocket LED flashlight is a very nice
little light which utilizes a single 5mm LED, driver circuit,
lens, and one AA cell to produce a spotlight-like beam.
Body description: The body of the AL-91AA is anodized
aluminum with a very nice finish. Machining appears very good and
there was obviously some quality control in place when making the body. There
are grooves running the length of the body, tailcap, and head to
provide grip when twisting the head or tailcap. A large flat
panel is machined into the side for logo printing. The head and tailcap
are removable and are sealed for water resistance. The tailcap contains a
spring for the negative contact and is flat which allows the light
to stand on end when the keychain attachment is removed. The head serves as the
switch.
Bezel/Head: The front of the light contains the single 5mm LED used
to produce light, a driver circuit to power the LED with one AA cell, and
a convex lens which allows the light to produce a tight spotlight-like beam.
The driver circuit also acts as a regulator to provide fairly constant
output from the light during the life of the batteries. I did notice that
there was a little "crud" on the positive contact under the head. Since the
head is completely removable, it was a simple thing to unscrew the head and
scrape off the gunk with my fingernail. Two well lubricated O-rings seal the head and protect
against the entry of water.
Output: Output is in the form of a concentrated spot with two
dark lines on either side. These are artifacts produced by the bond
wires on the LED which are then projected by the lens at the front of the head. Based
on the position of the bond wire artifacts, I can tell that the
LED is not quite centered behind the lens. There appears to be no
way to open the head further to straighten the alignment of the LED.
Besides, it really doesn't impact usage
at all. Rings of light surround the main spot providing a spillbeam of sorts.
Overall, the beam is quite useful for close tasks without being excessively tight.
The beam is a high color temperature and has a visible bluish tint.
Personally, I'm not a big fan of spotlight-type lights
because they often produce such a concentrated beam
as to make them nonfunctional as a flashlight. This
one really doesn't have that problem thanks to the slight
spillbeam which becomes bright enough at close range
to be genuinely useful.
Beam at one meter at target center and enhanced picture
at target edge to show spillbeam.
Runtime Plot: Pretty nice regulation going on here! 6 hours to 50%.
Runtime
completed with Duracell batteries. More information
on runtime plots is available HERE.
Switch: The head of the light is the switch. Tighten for on, loosen for off.
The action is very smooth without any catches or snags. There is enough
resistance that it should not turn on accidentally, but it can be
activated with only one hand.
Seals: Two well lubricated O-rings seal the head and one large O-ring
seals the tailcap. I'd call it dunkable at the least. If it gets wet inside,
just disassemble as much as possible without tools and let it dry
before next use.
Ergonomics: Nothing special to report here. It's a small light but
a convenient size and easy to use. The switch works well and the grooves
on the body/head/tailcap provide adequate grip to turn it on and off and to
change the batteries.
Size compared to a common 2AA aluminum light
Batteries: A single AA cell powers the light (included). To change
the cell, unscrew the tailcap, drop out the old cell, drop in a new
cell positive first, reattach the tailcap fully.
Accessories: A keychain attachment is included and attached
to the tailcap via a small hole in the tailcap. I personally think
it looked goofy and removed the keychain with a pair of needlenose pliers.
What I Liked: Water resistant,
Inherently tough and impact resistant, Regulated/long battery life,
Good output, Easy battery change, Lightweight, Stands up, Nice machining
What I Didn't Like: I'm not a fan of spotlight-type
flashlights, but this one isn't too bad at all.
Other Things I Noticed: Positive contact inside
the head needed a quick cleaning.
Conclusions: Good little AA cell utility light. Nice output
and great runtime. Very handy size and weight. Campers may find it useful for
tasks around the campsite. Good for reading maps in the car.
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