What does the luminous efficacy depend on and how efficient can a white LED actually be?
www.dial.de
If you believe these guys, then there will be no breakthrough of 500 lm/W with the current technology. Perhaps in the future some nanotechnology or new materials will be able to do this, but this is still unknown
Well, I watched the movie, Wishmaster, where something like a genie granted wishes exactly as it was said, without considering the accompanying effects. Something like the old joke, when a man ordered enlarge one of the intimate parts of the body from the genie, and when it turned out that it cannot stand up and be firm, but hangs like a snot, it became clear that desires needed to be formulated more clearly. I think the same should apply to the consideration of any contracts before signing them.
If we have 1AA, then we can make a flashlight that produces 500 lumens, but we'll have to cut some corners:
The maximum efficiency of LEDs, if nothing has changed in technology, is around 5 mA
Advantages and drawbacks of higher drive currents for LEDs including the effect on reliability, efficacy, luminosity, chromaticity, design complexity and cost.
www.digikey.fr
The size of the lantern is indicated as 3 inches, but it does not say in which direction, which means we can make a Cube measuring 3*3*3 inches and powered by 1 AA
There were also no requirements for weather protection, which means we can make IP00
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This will also increase efficiency, since we will not use protective glass and any optics other than the primary LED optics
There were no requirements for the quality of light other than that it be white, so you can use diodes with the highest color temperature, or use XLamp XP-G3 Royal Blue and add a little phosphor (very little) to bring the CRI to at least 10-15. Or from real LEDs, I found these, the highest efficiency that can buy
Here 267 lm/w, at a current of 5 mA I think the efficiency will be higher, say 270 lm/w. To get 500 lumens, we need 1.8 W. At a voltage of 5.52 V, the current should be 326 mA. If we drive diodes with 5 mA, we need 65 LEDs. 49 pcs (7*7) can be quite comfortably placed on a 3*3 inch board - on a grid with 5 mm of space between diodes for current paths, and 16 diodes can be placed on the side plate
We also need a very efficient driver with 1 operating mode. For example, we can find it with an efficiency of 80%, then the flashlight will consume 2.25 W from the battery.
And we must not forget about losses, so all conductors and contacts should be made of pure silver (after all, we were not given a price limit for the flashlight in the task)
To prevent the battery from being too depleted, you can use PWM, I think 1 Hz will be optimal
Of course I made too many assumptions, but if there is an AA battery that can pulse 2.25 W, then we met all the conditions, since the operating time of the flashlight was not indicated
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