Underwater Kinetics 4AA eLED

Provided for review
by the kind folks at:

5 Stars

Light Type: Luxeon I LED
Light Class: Rough Use / Hazardous Environ.

Short Description:

The Underwater Kinetics 4AA eLED (UK 4AA eLED, henceforth) is a compact LED light which runs on common AA alkaline batteries. The body and form factor is very similar to the regular UK 4AA xenon. The regulated LED module found in these lights is available separately as a drop-in replacement part for people who already have the xenon 4AA model. You can get the complete light or just the regulated LED lamp assembly from BrightGuy.com.

The UK 4AA eLED is made of a high impact polymer (ABS) with a rubber shrouded bezel. The body has molded grooves for grip, helmet and lanyard strap attachment points, and a pressure equalizing vent on the tail end. There is an o-ring seal to prevent the entry of water around the bezel. The light is advertised as watertight and dustproof. The lamp module contains a side emitter Luxeon I LED, an integrated smooth silvered reflector in a ring shape around the emitter, and a regulator circuit to provide constant light output for 10-12 hours with diminishing light provided thereafter for around another 80 hours. The rubber covered and textured switch is a press on-off type with a momentary blink option available by partially depressing the switch. 4AA batteries are required for power and are included in the package.

This light is designed for industrial applications and has the following hazardous location ratings listed on the packaging:


Size Reference
Size vs. common aluminum 2-AA light
Bezel picture
Beam Profile

Detailed Information:

Underwater Kinetics has done it again! This time taking their very popular 4AA form factor and adding in a Luxeon Star LED for light which will never "blow" like a regular bulb and a regulator circuit that produces dead constant output from the light. My meter readings indicate that the eLED puts out 50% more light than a common 2AA aluminum flashlight and it should continue to produce about that much light for around 10 hours as a result of its regulator before starting to dim. All of the features found in the 4AA eLED make for one super light.

The body is made of impact resistant ABS. Very solid construction, advertised as drop tested to 6 ft. You should be able to beat this light up pretty good without any problems. The spring holding the batteries in place inside seems pretty durable as well. On the side are loops formed in the plastic for straps or a lanyard and on the tailcap is a vent to equalize pressure in the light.

Loops behind head for lanyard/straps

Pressure vent in tailcap

The separately available eLED lamp module with integrated regulator circuit fits the UK 4AA AS2, Mini Q40 and the UK 2L. Because the bulb is a Luxeon LED it should never blow and it will take a very long time (thousands of hours) to wear it out. The module also contains a hydrogen catalyst to try to neutralize any hydrogen gas that builds up inside the light during use (from the natural action of the batteries as they are used up).

Output is very good, about 50% greater than an aluminum 2AA flashlight (you know which one I mean :-). Beam quality is very good with a smooth spot and bright surround. It is permanently focused, so no adjustments are ever necessary.

I decided to do a runtime test to see how good the regulator really was. After 10 hours I gave up on the runtime testing. The result? Here it is!

Now keep in mind that my testing may not be perfect, but the light was clamped in place, the meter was not moved, and I checked on it about every half hour long enough to turn on the meter and get a reading. Over 10 hours there was about a 6% drop in output. It was still shining about 94% as bright as when it started! During the inital 30 minutes where there was a slight drop of less than 3% and during the next 9½ hours there was again less than a 3% drop in output. This is really good regulation!

If placed on its head while on, the light from the lamp filters between the rubber shroud of the bezel and the body of the light through the clear polycarbonate bezel material. This creates a glowing ring which indicates that the light is on.

The switch, protected by a ribbed rubber cover, makes a barely audible spring-type click when depressed and locked on. The switch allows one-handed operation of the light. The bezel can be rotated about 1 full turn to "lock out" the switch, preventing the light from coming on accidentally in a toolbox or backpack. Although exposed, the O-ring does not disengage the bezel when "locked out", so the water resistance of the light is not compromised.

Water resistance is very good, equating to my rating of "dunkable". It is waterproof, but not rated for diving applications. The O-ring should be kept lubricated with silicone grease when necessary. If the light floods, it should be disassembled and allowed to dry.

As should be obvious from its name, the 4AA takes 4 AA batteries. Simply unscrew the bezel all the way and remove the lamp module to insert the batteries. Battery polarity is indicated on the body of the light.

The light comes with 4 Duracell AA batteries in the package. Separately you can purchase 3 types of helmet clips, a safety (traffic) wand, and nylon belt pouch.

What I Liked: Waterproof, Dustproof, Smokeproof, Tough/impact resistant, Great battery life, Good output, Easy battery change, Lightweight, Hazardous location approvals, Dead solid regulation for many hours

What I Didn't Like: Would have preferred brighter output, but still more than adequate for most uses.

Other Things I Noticed: Cannot stand on end, Not dive capable.

Conclusions: Output was quite a bit dimmer than I expected, due in part to the fact that the body is plastic and there is no way to get rid of the damaging waste heat that would have been created by driving the Luxeon at higher current levels. Overall the eLED puts out about 50% more light than a common 2AA aluminum light (per my readings) which isn't too shabby. Couple this with its advertised 10 hour flat regulated runtime and you have a great long running, practically indestructible, extremely reliable flashlight. Add in to all of that the hazardous location ratings and the really great initial price from Brightguy.com (and a not-so-bad regular price at any rate) and we have our FIRST 5 POINT POLYMER FLASHLIGHT !!!!. Congratulations to Underwater Kinetics!

Quick Facts Table:

Review Date ............................. February 2004
Case Material ........................... High impact ABS
Case Features .......................... Grooved for grip, lanyard and helmet attachment points, safety vent
Case Access Type .................... Unscrew Bezel
Switch Type ............................. Click on/off with momentary capability
Reflector Type ......................... Smooth silvered ring around bulb
Lens Type ................................

Clear plastic

Bulb Type ................................. Luxeon I side emitter LED / reflector lamp assembly (one piece)
Beam Type ............................... Spot with bright surround
Beam Characteristics ............... Bright center, bright surround, and wide corona
Throw (Lux) at 1m (click for description) ~ 203 at beam center. (14.26 Comparison Chart equivalent)
Overall Output (click for description) ~ 890 (8.90 Comparison Chart equivalent)
Battery / Power Type................ 4 AA alkaline batteries
Battery Life (advertised) ........... 10 hours regulated constant brightness, 80 hours diminishing
Environmental Protection ......... O-ring seal, Waterproof vent and switch
Special Items of Note ............... Hazardous locations approvals on side of light
Warranty .................................. Lifetime (!)
Retail Cost ................................ Special: $20 US$ at BrightGuy.com at time of review


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