My current favorite practical light

Solstice

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Underwater Kinetics Unilite 4AA eLED. Here's a Pic and a cheap place to buy: http://www.premieronlineproducts.com/scripts/prodView.asp?idProduct=345
This light is an update to the very popular UK 4AA eLED light reviewed by Quickbeam here: http://www.flashlightreviews.com/reviews/uk_4aaeled.htm
Mini Review:
The light is basically a combo of UK's existing incan Unililte (the fact that body says eLED and its got the LED lamp are the only differences from the original Unilite) and their the 4AA eLED model. Read Doug's review to see why the eLED is so great- almost waterproof, long flat regulation, etc. Compared to the eLED, there are two differences/additions: the right angle bent head swivel adapter and the clip. The 90 degree head w/clip combo offers an amazing amount of additional utility to an already excellent light- the body of the light can be clipped vertically in a pocket or even to a belt/top of your pants or shirt, and the light projects forward for hands free use without the headlamp geek factor. The very wide spill of the side emitter w/reflector make specific aiming uneccesary. Additionally, the body of the light w/the clip are very stable lying on their side on the ground, so the "neck" may be rotated to whatever upward angle is desired or shoot straight up to light up a room. On the minus side, since the neck has to rotate, you must use the switch- no twist on, and one more o-ring seal is another potential in route for water. However the utility of this system combined in a hazardous environment rated light w/cheap batteries makes for an awesome practical light for camping or what have you. As others have said, I feel it could be a bit brighter and have a bit more throw vs. flood, but in an actual emergency situation, this light would be a hard one to beat for versatility and general user friendliness.
 

Solstice

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Sorry about the double post. I tried deleting to no avail. Mods, please delete the other post (spelling errors).
 

LightObsession

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It's interesting that premiereonlineproducts lists the output at 30 lumens, twice that of the original 4AA eLED, but keeps the run time the same as the original. That must be a type-o. It doesn't seem likely that the output doubled, but the run time stayed the same unless the LED efficiency doubled. A doubling of efficiency would be great.
 

Solstice

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No, I definately don't think this light is 30 lumens- The marketing hype is from Underwater Kinetics. They're probably just listing what the LUX I is rated for, not what its actually driven at.
 

LightObsession

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Thanks for the review Solstice. I may consider the Unilite eLED rather than the original 4AA.
 

asdalton

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Yes, it's a mistake. Other parts of the product discription say that it's as bright as five 5mm LEDs, which is accurate since the Luxeon is underdriven. The "30 lumens" figure comes from carelessly copying a number from the Luxeon spec sheet. Even if the emitter were driven at the full specified current, a claim of 30 lumens would still be an overestimate due to losses in the optics.

Lumileds is going to need to release some more efficient emitters soon, or other products will overtake them. The Nuwai 2xAAA LED light has a single emitter that gives the same brightness and runtime as the UK 4AA eLED, and that's using 2xAAA instead of 4xAA. The Nuwai has inferior regulation to the UK, but the disparity is still amazing.
 

LightObsession

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The UK 4AA eLED has a regulated run time of 11hrs (verified independently). The Nuwai 2AAA output drops rapidly and run time is nowhere near the 4AA eLED.
 

PJD

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On Roy's run-time plot of the Nuwai 2XAAA (using lithium AAA's), it shows a run-time of over 9 hours to 50% output...3 hours more than the same light with alkaline cells, with a much flatter drop-of rate.

PJD
 

asdalton

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[ QUOTE ]
PJD said:
On Roy's run-time plot of the Nuwai 2XAAA (using lithium AAA's), it shows a run-time of over 9 hours to 50% output...3 hours more than the same light with alkaline cells, with a much flatter drop-of rate.


[/ QUOTE ]

I am using lithiums in mine, so this is the performance curve that I was thinking of. Also, the Nuwai running on lithium batteries is noticeably brighter than the UK. I'm sure that the UK will run for even longer from lithium AA cells (15+ hours?), but the runtime is not commensurate with the UK having > 4X the battery capacity of the Nuwai.
 

LightObsession

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Yes, the Nuwai 2xAAA does have a much longer and much flatter run time with lithiums, but the UK 4xAA also has much longer run time on lithiums. The Nuwai 2AAA .5w doesn't have the same brightness as the UK 4AA for anywhere near the same amount of time when both are using alkaline or both are using lithium. The UK has flat output on alkaline or lithium. The Nuwaii only has flat output using lithium. The Nuwai output drops significantly in the first 30 minutes of use. Nuwai .5w 2xAAA initial brightness is great if you get a bright white one - not so great if you get a dimmer blue one. I have two brighter white Nuwai .5w 2xAA lights and two of the dimmer blue. The UK 4xAA lights don't appear to have this inconsistency of brightness and tint (I don't own a UK 4xAA light, so I'm basing this on what I've read). I wish my Nuwai .5w 2xAAA had the constant brightness and run time as the UK 4xAA light.

All that being said. I really like my two Nuwai .5w 2xAAA lights that are white and bright. I usually only use them for a few minutes at a time. They're much smaller than the UK 4xAA light.
 

LightObsession

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My understanding is that the Nuwai .5w lights are dimmer on rechargeables than with alkalines. The 1xAAA has been reported so. I don't know if anyone's tried the 2xAAA.
 

NotRegulated

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[ QUOTE ]
mossyoak said:
my favorite practical light is the princeton tec attitude/rage combo light for every situation

[/ QUOTE ]

Those are great choices. I always keep an Attitude with me in my bag or car. It is low cost, waterproof, long runtime and practical even though I usually EDC a Surefire. I like the newer style body with the clip better than the old body. The rage bulb will also fit inside the Attitude body if you need a light with more throw.
 

asdalton

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There are advantages of having true regulation and constant brightness, and I won't argue with that. But what I said before still stands: the UK 4AA is not very efficient.

Battery capacity (alkaline)

UK: 4xAA, 2850 mAh, ~1.1 V (avg.) during lifetime
Energy content: 12.54 watt-hours

Nuwai: 2xAAA, 1250 mAh, ~1.1 V (avg.) during lifetime
Energy content: 2.75 watt-hours

Light output (on alkalines)

I have observed that both lights are equally bright on fresh alkaline batteries. I will estimate this value, based on what I remember from other threads, as 10 lumens. Since both lights are adjusted to this starting value, any errors in this estimate will affect both lights equally.

UK: constant brightness, 10 lumens for 13 hours (best case)
Integrated output: 130 lumen-hours

Nuwai: dimming, starts at 10 lumens but has an average over the 11-hour battery life of ~5.5 lumens (by integrating Roy's graph)
Integrated output: 60.5 lumen-hours

Net average efficiency (batteries to beam)

UK: (130 lm-h)/(12.54 W-h) = 10.4 lm/W
Nuwai: (60.5 lm-h)/(2.75 W-h) = 22 lm/W

So the UK emits > 2x the total light of the Nuwai over one battery cycle but requires > 4x the battery energy to do so. This is in spite of the fact that the UK has the advantage of stepping down from a high voltage, as opposed to having to boost the voltage.

I now suspect that the UK's regulation uses a transistor-type regulator rather than an inductor. This would make the regulator unable to turn the excess voltage into useful power, and it would require the flashlight to draw the same current from the batteries that it sends through the LED. The quick current calculation (2850 mA-h)/(13 h) = 220 mA supports this hypothesis.
 

LightObsession

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[ QUOTE ]
asdalton said:...The Nuwai 2xAAA LED light has a single emitter that gives the same brightness and runtime as the UK 4AA eLED, and that's using 2xAAA instead of 4xAA.

[/ QUOTE ].... This statement from your first post has a much differtent implication than your most recent statment. This 1st statement implies that both lights have the same brightness and run time.

Your last post explains your understanding that the numbers you present suggest that the Nuwai .5w 2xAAA makes more efficient use of it's power source than the UK 4xAA eLED. This is a different point than saying that they have the same output and run time. I think I now understand what you were trying to say in your 1st post.
 

Doug Owen

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[ QUOTE ]
asdalton said:
I now suspect that the UK's regulation uses a transistor-type regulator rather than an inductor. This would make the regulator unable to turn the excess voltage into useful power, and it would require the flashlight to draw the same current from the batteries that it sends through the LED. The quick current calculation (2850 mA-h)/(13 h) = 220 mA supports this hypothesis.

[/ QUOTE ]

Yes, but actually *checking* it finds out the truth....it's an active converter. Current draw at six volts is about 160 mA, it *rises* (a clear sign it's not linear) to 250 or more as the battery voltage drops.

IMO the UK has earned the praise, it's a mature, well thought out and implemented product. Recommended.

Doug Owen
 

asdalton

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Thanks for the information about the regulator circuit. I tried to look at the innards of my UK, but I couldn't really see anything through the plastic, and I didn't want to take it apart and wreck it. /ubbthreads/images/graemlins/icon15.gif I was lucky and got one with a nice warm-white LED.

It appears that the Luxeon itself (and/or optics) should be blamed for the poor overall efficiency. This means that the UK could be a prime candidate for modding as more efficient LEDs come out.
 

LightObsession

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Doesn't the low capability of the plastic housing of the UK 4xAA light to dissipate heat from the LED assembly limit the amount of power that can be supplied to the LED without overheating the LED. My understanding is that the LED can't be safely driven any harder in this light because of the heat factor. So, as you suggest, a more efficient LED is probably the only way to get more light out of this light.
 
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