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Thread: LED versus inc flashlights

  1. #1
    Unenlightened
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    Default LED versus inc flashlights

    Pretty simple question that I'm just too lazy to answer myself. Out of curiosity, what is the battery lifetime of a cheap 2xA battery incandescent flashlight compared to a cheap 1xA battery LED flashlight. On the one hand, the LED consumes a lot less current. On the other hand, the 2xA inc flashlight has two batteries. The LED is probably running 40ma at 1.5v, but I'm not sure what current the inc lamp is running at 3v. Off-the-top-of-my-head answer appreciated. Factor of two? Factor of ten?

  2. #2

    Default Re: LED versus inc flashlights

    Given there are a whole bunch of variables regarding fuel source, output, volts needed and other things, let's just say way more than 2:1.

    Ok, take a 2aa light bulb'd cheapie versus an LED 2aa cheapie with similar output using same kind of batteries figure around 10:1.
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  3. #3
    *Flashaholic* StarHalo's Avatar
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    Default Re: LED versus inc flashlights

    Most LED lights are regulated and most incans are direct drive, so unless "runtime" is counted as time useable light is emitted, the LED will win by a ridiculous margin. But back in the incan days, you counted the time that the flashlight still functioned as a flashlight; a typical incan Maglite will have max brightness on fresh batteries at the very start, and then output will immediately plunge almost straight down for the first ~20% of runtime, then the output levels off to a slow decline for the remaining ~80% of battery life. The result is that nearly all of the runtime curve occurs at ~25% of max output. So as long as you count that, the incan's runtime isn't bad, but once flashaholics came on the scene with output charts, runtime was considered "to 50% output", so if you go by that standard, most 2xAA incans last maybe 15 minutes.

  4. #4
    *Flashaholic* Burgess's Avatar
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    Default Re: LED versus inc flashlights

    I can report for a fact,
    after doing my own Run-Time tests on my
    Mini-MagLite 2AA (with the "pink ring" bulbs)
    and the (then current) Energizer Alkalines in 1997:

    You could count on 5 Hours of light,
    and perhaps even stretch it out to 6.

    Of course, as StarHalo wrote,
    output is decreasing from the very start.

    I had told myself to just expect 5 Hours.



    BTW --
    This flashlight/bulb/battery combination
    managed to serve me QUITE WELL
    for 22 Years of EDC use !


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  5. #5
    *Flashaholic* StarHalo's Avatar
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    Default Re: LED versus inc flashlights

    Yeah, I remember my dad swapping out the batteries in his occasional-use about-the-house MiniMag roughly once a year, it worked for about three decades in that role. I got him a Quark Mini AA Neutral when it came out [which I still consider one of the best 1xAA LED lights ever made,] he never used it.

    Quickbeam's chart of the 3D Mag from way back in the day shows you what to expect from incan direct drive:


  6. #6

    Default Re: LED versus inc flashlights

    Depending on the incan bulb you can estimate it probably draws about 250ma at 2.25v or about 6 times the current the LED does to start.
    The one thing that one also has to consider is useful lumen output of incan vs LEDs as voltage and current output drops as the batteries are depleted. I think the main factor that is hard to quantitize is what level of output is needed or useful if tint (CRI) isn't an issue and low lumen output is useful then a 1AAA LED light can compete with a 2AA incan on output/runtime.
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  7. #7

    Default Re: LED versus inc flashlights

    Quote Originally Posted by bykfixer View Post
    Given there are a whole bunch of variables regarding fuel source, output, volts needed and other things, let's just say way more than 2:1.

    Ok, take a 2aa light bulb'd cheapie versus an LED 2aa cheapie with similar output using same kind of batteries figure around 10:1.
    I'm confused 🤔. The way you've written this, it makes it look like you're saying that the 2aa bulb'd cheapie will shine 10 times longer than the 2aa LED cheapie !!! I could be looking at this wrong 🙄 but syntactically speaking, the order of compared items should match the order of the ratio. My understanding (and again, I could be wrong) has been that LEDs consume MUCH less energy from a battery than does an incandescent bulb that provides a similar level of light output. Unconfuse me 😉.
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  8. #8

    Default Re: LED versus inc flashlights

    Post 1 asked starting with a bulb then LED. And if LED was 2:1 efficient versus a light bulb. I answered 10:1.
    John 3:16

  9. #9
    *Flashaholic* idleprocess's Avatar
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    Default Re: LED versus inc flashlights

    In terms of simple efficiency, LEDs consume perhaps 20% of the power on a LPW or Lumens (useful light output) Per Watt (instantaneous power output) basis relative to incandescents or ~5:1 runtime for LED relative to incandescent. If you use two cells for the incandescent you would expect the LED to run ~2.5x as long on one cell producing identical lumens.

    As others have alluded to previously, the above doesn't take into account the fact that even relatively cheap LED flashlights are regulated and can typically draw cells down to near zero - often without performance degradation (or simply forcing graceful stepdown as the cell depletes). Contrast this to direct-drive incandescent lights which will have you swapping the cells earlier than theoretical maximum runtime since the output will have dropped to a small fraction of peak. The availability of multiple modes on even cheap LED flashlights leads to even longer runtime in practice so long as you're using lower modes for a decent percentage of the time as most users tend to.

    Regulated incandescents exist, but they are vanishingly rare in the wild - presumably due to the modest gain in peak runtime such a device could produce at the expense of trailing runtime and the notification such behavior provides to the user. The circuitry to do so likely also matured with LED flashlights which have eclipsed incandescent flashlights in the marketplace. Of the regulated incandescents out there, I believe their main use is soft start so as to prolong filament life.
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  10. #10
    *Flashaholic* carrot's Avatar
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    Default Re: LED versus inc flashlights

    I recently did a little digging on the subject.

    It looks like a typical incandescent bulb during the heyday of hotwire is less than 15 lumens per watt. I am guessing there is even lower efficiency in a flashlight incandescent bulb due to not running at optimal voltage with battery sag.

    When LEDs first took over the scene in flashlights, I think the Luxeon III era, we were getting about 40 lumens per watt.

    Cree XR-E came on the scene at more than double that, 80-100 lumens per watt.

    Now current generation Cree XP-L are getting about 200 lumens per watt in best circumstances.

    So you could say a modern LED flashlight is 10-20x more efficient than an incandescent flashlight. Whether you spend that efficiency towards runtime or brightness is on a sliding scale, up to the specific implementation. But at this point, by comparison, you can have both. It is becoming alarmingly “reasonable” to have a 1000 lumen flashlight that fits in your pocket and runs for an hour or maybe two. When incandescent was at its best, we thought 50 lumens for an hour was pretty good.

    Once we got into Luxeon III territory, that basically cut off the entire track of incandescent technology. We had regulated incandescent using circuitry that would only have gotten better. There was an entire avenue of development that would improve incandescent efficiency easily 2x, using infrared reflective coating. There are better ICs now that are wildly efficient compared to what we had back then.
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  11. #11
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    Default Re: LED versus inc flashlights

    Quote Originally Posted by carrot View Post
    I recently did a little digging on the subject.

    It looks like a typical incandescent bulb during the heyday of hotwire is less than 15 lumens per watt. I am guessing there is even lower efficiency in a flashlight incandescent bulb due to not running at optimal voltage with battery sag.

    When LEDs first took over the scene in flashlights, I think the Luxeon III era, we were getting about 40 lumens per watt.

    Cree XR-E came on the scene at more than double that, 80-100 lumens per watt.

    Now current generation Cree XP-L are getting about 200 lumens per watt in best circumstances.

    So you could say a modern LED flashlight is 10-20x more efficient than an incandescent flashlight. Whether you spend that efficiency towards runtime or brightness is on a sliding scale, up to the specific implementation. But at this point, by comparison, you can have both. It is becoming alarmingly “reasonable” to have a 1000 lumen flashlight that fits in your pocket and runs for an hour or maybe two. When incandescent was at its best, we thought 50 lumens for an hour was pretty good.

    Once we got into Luxeon III territory, that basically cut off the entire track of incandescent technology. We had regulated incandescent using circuitry that would only have gotten better. There was an entire avenue of development that would improve incandescent efficiency easily 2x, using infrared reflective coating. There are better ICs now that are wildly efficient compared to what we had back then.
    Can't tell you how many times I dreamed of where incandescent technology could have gone. The A2, and some of the various Willie Hunt regulators/soft start stuff, along with mods here on CPF at least gave us a small taste of what could have been.

    Wasn't there some talk of using nanotechnology in incandescent bulbs?

  12. #12
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    Default Re: LED versus inc flashlights

    Quote Originally Posted by idleprocess View Post
    Regulated incandescents exist, but they are vanishingly rare in the wild
    Actually not so. They are enormously common on people's shelves, even though you surely won't find them for sale anymore. Loads of inc flashlights being tossed these days.

    But what I'm hearing, in answer to my original question is that a runtime differential of x2.5 or so is a best-estimate for a modern LED one-cell flashlight compared with an archaic two-cell inc light.

  13. #13

    Default Re: LED versus inc flashlights

    I think the biggest enemy of incans is radiated heat. Incans are good in houses in the winter as the heat isn't wasted in colder climates but in the summer you pay for the inefficiency of incans twice, once for the light and the second time to remove the heat added to your house.
    The only way incans can make a comeback is if they figure out how to make them as efficient as LEDs either more light for less power or capture the excess heat and turn it back to power. At work on a cold day I was surprised that someone was using a 500 watt halogen light till they told me it wasn't for the light output but was a heater and I had soaked gloves and put them up near the glass about 6 inches or so away and could see steam coming off my gloves had to pull them back to about a foot to keep from burning my hands. Perhaps they can make an incan that works in a liquid solution that can transfer the heat like a steam engine and power a generator to capture the throwaway heat.
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  14. #14
    *Flashaholic* idleprocess's Avatar
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    Default Re: LED versus inc flashlights

    Quote Originally Posted by carrot View Post
    Once we got into Luxeon III territory, that basically cut off the entire track of incandescent technology. We had regulated incandescent using circuitry that would only have gotten better. There was an entire avenue of development that would improve incandescent efficiency easily 2x, using infrared reflective coating. There are better ICs now that are wildly efficient compared to what we had back then.
    Quote Originally Posted by DayofReckoning View Post
    Can't tell you how many times I dreamed of where incandescent technology could have gone. The A2, and some of the various Willie Hunt regulators/soft start stuff, along with mods here on CPF at least gave us a small taste of what could have been.

    Wasn't there some talk of using nanotechnology in incandescent bulbs?
    Vybrant 2x bulbs look to have been a thing ~7 years ago. I believe those just used an IR coating.

    A different approach to IR coatings more recently hit ~3X with some filament redesign, supposedly with potential top go even further with more development of the technology.

    Just not sure that such developments are going to be as cheap as old-school 15 LPW incandescent bulbs were, which is a lot of the appeal for manufacturers seeking to minimize that upfront price. Could still emerge from the labs as a viable commercial product - just not something to bank on yet.
    I apologize that this letter is so long; I did not have time to write a short letter

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