Output per watt: Who's the king?

Output per watt: Who\'s the king?

It's easy to design a good $40,000 car. It's much harder to design a good $15,000 car.

Similarly, it's easy to produce a light with great total output by feeding it 5 watts. It's not so easy to produce a light with great output on 1 watt.

Which lights yield the highest lumens per watt?

In QuickBeam's Relative Total Output figures, recent lights seem to generate about 1000 output units per watt. By this measure, I believe that I've found two standouts:

Nuwai 2611X (1xCR23A), 1650/0.8W = 2062 units per watt.
Peak Glacier Bay (1xCR123A), 2400/1W=2400 units per watt.

Any others?

Re: Output per watt: Who\'s the king?

I would *assume* lights that are direct driven would be a starting point. I would then think that it would a question of the BIN. The new Nichas are probably tops for 5mm. When it comes to Luxeons, I am not sure if a 3 watt is more efficient than a 1 watt, but then it would also depend on the bin of the Luxeon.... Of course I could be completely wrong.

Re: Output per watt: Who\'s the king?

[ QUOTE ]
Geologist said:
I would *assume* lights that are direct driven would be a starting point.

[/ QUOTE ] So would I...but the Nuwai and Peak are fully regulated!

Re: Output per watt: Who\'s the king?

Lumens/watt or efficacy is independent of any driver efficiency and will be a function of the LED's inherent flux potential and its drive level. By that I mean a high flux bin will win out over a low flux bin. Any of the LED's will have increased efficacy as they are driven at lower levels of current. For a king, I would look towards a light using the new Nichia 5 mm's and one that is underdriving the LED's.

However, if you are looking at light output per watt of input, then the efficiency of the driver is significant and I would look to a DD light that is underdriving the LED.

I don't know how Quickbeam arrives at his light output units but certainly the efficiency of the optic package or the percentage of light transmission through the front end is a key factor and for this reason I would again look to the Nichia 5 mm's as likely candidates.

With a proper output measuring system, I am confident you will find the king is not a "bright" light. Of all of the LED lights I have, if I had to pick an entrant for efficacy king based on watts of input VS luminious output, it would either be a PD driven at 30 mA (low mode) or a LC I have in candle mode and under driven on a CR123. At the source of the LED, the PD would be better but given the loss of light through the optics of the PD, the LC in candle mode might prevail even though the LED is being driven at a higher level. Actually I have a HDS that would also be a contender on its lowest setting as well. /ubbthreads/images/graemlins/icon3.gif

I think my point is that you will probably find your "king" in a light that would be considered an under achiever in normal comparisons with other lights.

Re: Output per watt: Who\'s the king?

Interesting thought,
My most efficient lights are a Lambda MicroIlluminator running a R3J Luxeon at 155mA off a single AAA battery. It calculates out to around half a watt and is very, very bright for what it is.
My nFlex (variable output) equipped "8AA in 2D Mag" runs a WX1S LuxeonV LED. With the 9.6V NiMH battery pack providing 40mA on the lowest level (~10Vx.040x.92% regulator efficiency = 0.37 watts) it is brighter than the MicroIlluminator. The huge reflector in comparison to the Micro helps out alot but it can't beat and severely underdriven LuxeonV.
Maybe Don could run 1 watt into a X3T LuxV and see what it will do?

Re: Output per watt: Who\'s the king?

Then I'm guessing that an EternaLight with the newest Nichas using PWM on low power (or maybe just one LED) would be a major contender also, in spite of the extra juice used in the circuitry and microprocessor.

Re: Output per watt: Who\'s the king?

My Tri-LuxIII light (fatman driver) on low nearly matches my HDS EDC-U60 on the 30 lumen level, while consuming half a watt of power or less.

Re: Output per watt: Who\'s the king?

If you want to see a sampling of lumens/watt at the bare LED level, look at the "LED DB" link in my signature ... just keep in mind the huge margins of error when it has to calculate lumens from mcd and a beam angle. Much of the error is due to the 50% intensity figured used for beam angles - you lose a great deal with a tight beam angle because the omitted spill is a signifigant amount of light.

Re: Output per watt: Who\'s the king?

This mod of mine would be a good contender. It uses one 5 mm, 100 mA LED that is underdriven and direct-driven from a single 123A cell.

Re: Output per watt: Who\'s the king?

Here's a site that appears to use the same forumlas I do in the LED DB for converting Cd x beam angle to lumens:

http://led.linear1.org/lumen.wiz