What is the general power savings of an LED?

For example, what if you had two lights. One was an LED, and one was a typical incandescent. They both put out 100 lumens of measurable light. What wattage is the LED going to be sucking down? And what wattage will the incandescent be using? In short, how much more efficient are LED's, than incandescents? (of the exact same amount of light output, of course)

BennyLava said:

For example, what if you had two lights. One was an LED, and one was a typical incandescent. They both put out 100 lumens of measurable light. What wattage is the LED going to be sucking down? And what wattage will the incandescent be using? In short, how much more efficient are LED's, than incandescents? (of the exact same amount of light output, of course)

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maybe using 10-20% of the power of incan the LED could give off more light.
why? well consider....
humanity has yet to fully comprend the significance of LED lighting's properties.

rising above the Earth, compare a baloon to a kite to a plane or bird then compare all 3 to an ANTIGRAVITY device or vehicle. that partially explains the difference between 'traditional' thermally based lighting like fire, candles, oil lamps gas lamps and solid state lighting like LEDs. Flourscent lighting uses electricity to excite gasses, yet is not that efficently, LEDs are far more sophisticated.

other folks can give more technical info,comparing LEDs to incans, yet the significant difference in the operting principals by which each creates light are as different as the way altitude or "flight" is achieved by a bird, a kite, plane is to how an equal elevation or altitude would be achieved by an antigravity device!

Within the Surefire lineup...

Surefire A2 incan (90Lu), 8.4Vin:
10.7 Lu/W :candle:

Surefire E2L-KX2 (110Lu), 8.4Vin:
HI = 79.7 Lu/W :twothumbs

Despite this the A2 is still my preferred light... for various reasons beyond overall efficiency.

My back of the envelope calculations suggest about 10 to 1 efficiency ratio. This of course would be highly dependent on the type of LED and how hard it's driven. From my understanding, incandescent efficiency is more uniform, and less dependent on specific bulb/light/current combinations.

2xAA MiniMag ≈ 6 lumens for 5 hours (300 minutes) ≈ 1800 lumen minutes

2xAA Quark AA2 ≈ 210 lumens for 1.33 hours (80 minutes) ≈ 16,800 lumen minutes

2xAA EagleTac P20A2 MKII ≈ 230 lumens for 1.33 hours (80 minutes) ≈ 18,400 lumen minutes

So basically, the general rough estimate would be that an LED only requires about 10% of the power to output the same lumens that an incandescent does. And they last 10x longer. So how long until the gov't passes a law requiring only LED's for normal household use lol. I bet that could take a boatload of strain off the grid.

The 2AA incandescent torches run for ~2 hours.
When the first LED torches came out 10 years ago they all claim 10X runtime but they are so dim.
Now that LEDs are so powerful many 1AA LED lights only have runtime of 50 minutes. Much brighter but actually have less runtime.

Note the minimag calculated numbers are not useful as the light output is constantly dropping. It is not 6 lumens for the entire 5 hour run.

From
http://www.smartdeviceresource.com/device-reviews/maglite-led-flashlight-review-and-guide/#specs
Model - Bulb Type - Lumens (OTF) - Throw - Runtime
2 AA - Krypton --- 12 -------------- 104M -- 5H 15M
2 AA - Xenon ----- 14 -------------- 96M --- 5H 15M
2 AA - LED --------- 69 ------------- 101M -- 18H
The web page also have numbers for 2D and 3D Maglites.

You can surf through the bigchelis 10.5" sphere sticky and calculate approximate efficiency (Lumens / Watt) for yourself.

On many lights he lists the tailcap current in addition to the cells used. Lumens per Watt is Lumens / (Voltage x Tailcap A draw)

Its an estimation because Voltage is the nominal cell voltage, not the actual voltage under load.

BennyLava said:

So basically, the general rough estimate would be that an LED only requires about 10% of the power to output the same lumens that an incandescent does. And they last 10x longer. So how long until the gov't passes a law requiring only LED's for normal household use lol. I bet that could take a boatload of strain off the grid.

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And they cost 100x more. And they are extremely susceptible to heat, requiring elaborate thermal strategies for the brighter emitters. I love LEDs, and have been flirting with the idea of trying to build myself an SST-90-based light fixture, but "LED replacement bulbs" simply will not work as a "drop-in" replacement for regular or fluorescent light bulbs, except for things like desk lamps, night lights, etc. Without a fixture designed to pull the heat away from the emitter, the 100x cost LED ends up with only about 2x the lifespan of a regular bulb.

Thanks for the replies everyone, but I see a lot of seemingly unrelated posts here. I am just asking a very broad and general question, and as such I expected a broad and general answer. If you have a typical LED, and a typical incandescent, how much less power (in wattage) would the LED consume than the incandescent, if they were both rated at 100 lumens output? Not really concerned about specific flashlights and specific brands, or battery power/life. One member said the LED would likely only consume 10% of the power that the incan would. Anyone else agree? Disagree?

The 10:1 efficiency ratio applies to cold white LEDs. For general lighting you should compare incandescents to low color temperature and high color rendition LEDs. In that case I think the ratio is more like 6:1. That is about the same as fluerescent lights compared to incandescents. Current LEDs are not much better for home illumination than the CFL and other fluerescent lights they should be compared to.

It is depend on the efficiency of led and incan and this changes with working conditions.

Incan has higher efficiency when the light is more white, i.e. the filament temperature is higher A incan driven at the edge of destruction can reach 30 watt/lumen.

For led the efficiency depends on the led generation and how much current is going through the led. At full current the efficiency will be lower maximum. The maximum efficiency is around 150 lumen/watt.

Next you have to reduce for the loss in the flashlight, incan will usual have larger losses, because they radiate in all directions, where a led mostly radiates in a narrow cone. Only 60 to 80 percent of the light will get out of the light.

Note: Some uses efficacy instead of efficiency.

Also, the efficiency of an LED is highly dependent on temperature. As any LED gets hotter, it will be less efficient. So, your LED:incan ratio is dependent on manufacturer, emitter type, bin code, lot number, tint, current applied, and operating temperature on the LED side, and probably filament material and voltage on the incan side. (Did I miss anything?)

I think what everyone here is getting at is that there is no "broad and general answer", because it depends on a large number of factors. About all you can say is that LEDs are more efficient than incans. If you just need a SWAG for some reason, I second Jarzaa's 6:1 ratio (quite a few available emitters are still only advertising 70-80 lm/W or so, if you're not looking at the bleeding edge).

It will not be very long before we use Led in all our households and cars.Many cars are now using Led,s as a standard fit and my auto bulb catalog from my employer is coming out with upgrades with nearly every drop of the post mans call.The lighting section in my kitchen side of my catalog is now just full of Led lights and no others anymore.