How much more efficient are LED lights?

I distinctly remember when LED lights were first promoted by Art Bell on his radio talk show. I believe CC Crane was selling little 2AA 5mm LED lights and they were primarily promoted as having extremely long run time. Now of course, the trend has been to brighter and brighter lights with of course shorter run times.

Just how much more efficient are LED lights than top quality Incad lights? Never mind the fact that they don't break - just thinking about efficiency. Tks.

Until recently incans were ahead or even, but now LED's are slightly ahead. Thing is, for an incan to be at max efficiency, it has to be overdriven somewhat. As soon as the voltage starts to sag, efficiency drops. LED's keep putting out useful light way into the dim dim tail. Lots of times I don't even notice when my LED light is putting out 1/10th of its normal output because its batteries are pooped.

3mm, 5mm, and 10mm LEDs that run in the 10-40ma region, are significantly more efficiant than incandecent (2-4x+)... but high power LEDs are only slightly more efficiant.... A really good lux5 might use around 5-6W and make 100 torch lumens... A well designed high pressure lamp can achieve almost similar results.. (best example... the DRB-9VHP, uses about 7watts, and has somewhere around 150 torch lumens)... Most other incans are not nearly this efficiant though.... The P91- a solid 200 lumens from surefire- consumes nearly 20 watts- making it half as efficiant as the afformentioned lux5.

well for hotwire mods, most of the "light" produce are IR and UV light. so not so many energy is converted into visible light( don't tell me about heat produce, where did you think IR come from?)

I felt like bumping this from the dead, and extolling the virtues of an underdriven Luxeon LED.

I like the benchmark maglight 2AA vs LED with similar brightness. In this case the Peak Pacific on 1AA.
The graphs says most of it, but stop at 8-10 hrs. I got an additional 12+ more hours of "useable" light after that.

Pacific on 1AA: Inital Overall Output 6.5, runtime to 50% = 6hrs 15min, over 24 hrs to failure.
Minimag 2AA: Initial Overall Output 5.8, runtime to 50% = 41 min, with 5 hr 31 min to failure

I can't link to just the graphs so here are the full reviews:
http://www.flashlightreviews.com/reviews/peakled_pacific.htm
http://www.flashlightreviews.com/reviews/maglight_minimag.htm

0.8x to 20x

The new high efficiency 5mm operating at 10 t0 20mA is tens of times more efficient than the 1.5v incandescent keylight bulb.

The high wattage LED is probably not quite as efficient as a 12V 55W halogen.

I found that an SL4AALUX put out very nearly as much light as SF P60.

The P60 will be dim or out completely in about an hour. The 4AA will be just as bright in 4 hours...

Any questions?

Yukon_Jack said:

Just how much more efficient are LED lights than top quality Incad lights? Never mind the fact that they don't break - just thinking about efficiency. Tks.

Click to expand...

It depends upon whether you're talking about white light or color, and the wattage and voltage of the incandescent light you're comparing to.

Let's start with the area where LEDs do best-small light sources. Indicator incandescent lamps average around 2 lm/W. If you filter them to get colors then you do even worse since the filter absorbs most of the light. You end up with around 1 lm/W for amber, ~0.5 lm/W for red and green, and perhaps 0.25 lm/W for blue. LEDs do much better than that. Reds and greens are typically in the 20 to 40 lm/W range, or about 40 to 80 times better than filtered incandescent. Ambers typically give about 15 to 30 lm/W, or 15 to 30 times better. Blues average around 10 lm/W, about 40 times better. Whites fare the worst, but even commodity white LEDs these days give around 30 lm/W, or 15 times better than incandescents. The best 5mm whites are around 80 lm/W, or 40 times better. Therefore, in the area of very small amounts of light, LEDs are anywhere from 15 to 80 times more efficient.

Now let's look at low wattage, low voltage incandescents such as 6 volts and 5 watts. These are typically in the 10 lm/W area. Power LEDs these days such as Luxeons are around 30 to 50 lm/W, or 3 to 5 times better.

LEDs start to lose when you get into fairly high wattage, low voltage lamps such as 55 watts and 12 volts. These can better 30 lm/W, especially with an infrared coating. This is about in the same ballpark as power LEDs. However, power LEDs still have the advantage of much longer life. Of course, even in this area LEDs have a huge advantage if we're talking about colored light. A 55 watt, 12 volt incandescent puts out perhaps 1500 to 2000 lumens. If you filter that to get blue light you're down to 200 to 250 lumens. 12 watts worth of blue Luxeons will accomplish the same thing.

I've fabricated some navigation lights for a small sailboat using red, green, and white Luxeon LEDs driven at about one watt each. Light output is visibly greater for each color than the incandescent lights they are replacing, and the LED system is consuming 5 watts total compared to the 24 watts consumed by the incandescent system that has been replaced. That makes a huge difference when the lighting system is powered by a small lead-acid battery like this one is, and reliability should be much higher too.