Headline: LED Spotlight May Actually Work

Sunbolt LED spotlight

When I read about the 11,000-lumen, 200-watt, two-kilometre-naked-eye-range, waterproof, $US7400 FoxFury Sunbolt 6 Mega Spotlight, I naturally assumed its specs were pretty much 100% claptrap.

It's very hard to make a super-powered LED light. Durable, efficient, bright-for-its-size, not-terribly-expensive; all that, LEDs can do. But they're not quite there for spotlights yet.

It is, however, very easy to throw around some weasel words concerning the capabilities of a non-super-powered LED light, so that's what I assumed FoxFury had done.

But I was wrong. They're actually only fibbing a little bit.

Their first bit of close-to-the-wind sailing is their claim - which I presume came from a press release, since it doesn't seem to be mentioned on the Sunbolt's product page - that the spotlight has the power of "7 car headlamps". 11,000 lumens is indeed about seven times the output of the 1962-vintage basic "H1" halogen headlamp bulb, but many more powerful and more efficient automotive lamps exist today.

The "naked eye distance vision" part is questionable, too. The Sunbolt is claimed to have an eighteen-degree beam, which at the stated maximum throw range of two kilometres will light a circle about 634 metres in diameter, with an area of 315,696 square metres. Distribute 11,000 lumens over that circle and you get 0.035 lumens per square meter, or lux.

The average dark-adapted human naked eye can see - in grainy monochrome - in light levels down to 0.1 lux; 0.035 is just barely possible, but practically speaking it's completely useless for spotlight applications. That's because dust in the beam will glow much brighter than the beam can light such a distant target.

It's possible that the FoxFury beam is sufficiently centre-weighted that there's a smaller spot in the middle that makes it to 0.1 lux at 2km, but it's disingenuous to pretend that this gives it a real, useful, two-kilometre throw. Much better to specify maximum throw as the range at which it averages one lux over its whole beam circle; going by the quoted output and beam-width numbers, that'd be a range of only about 375 metres, if I haven't flubbed my inverse-square-law calculation.

The raw power and output numbers, though, are usually where the claptrap lies in LED-lamp publicity. But getting twelve LEDs to draw (very slightly) less than 200 watts and output 11,000 lumens actually is a plausible specification, today - provided you use multi-die fifteen-watt LEDs. Those are technically each six LEDs in one package, so this is really more of a 72-LED spotlight. But who's counting.

The basic luminous efficacy number - 11,000 lumens from 200 watts gives 55 lumens per watt - is nothing special these days. If the LEDs are reasonably well-cooled then they ought to last a long time, too. They'll slowly lose brightness, which could cause problems for scientific or movie applications, but won't be perceptible to most users for a long time.

So yes, this really is a pretty serious spotlight. Don't expect it to actually create a circle of daylight at two kilometres, but the rest of the specs seem pretty much kosher to me.

10 Responses to “Headline: LED Spotlight May Actually Work”

  1. Changes Says:

    The big question is, of course, why go to all the trouble and expense of a multi-LED-multi-die contraption when a HID will do the job just fine for less money.
    I love LEDs and pride myself on not having a single incandescent flashlight (much like you, I seem to have a growing collection), but if I had to get a Serious Spotlight I'd get a HID.

  2. demiller9 Says:

    I think their claim of "7 times as strong as a headlight" is not a stretch. Remember that they are in the US, and our headlights are limited by law and are weaker than other parts of the world. The high beam on many current US cars is only 1200 lumens (an 9004/HB1 lamp). There are others (9007/HB5) with 1350 lumens.

  3. FuzzyPlushroom Says:

    Maybe they mean low-beam headlamps? I know my car (an American-market Mondeo) has some of the worst low-beams possible - I could do better if I JB-Welded a pair of cop-issue six-D-cell incandescent Maglites on my front fenders.

  4. evilspoons Says:

    How I loathe US headlight laws and how they affect me in Canada. I wish we followed the Commonwealth and had REAL headlights around here! My old '87 Volvo 740 is suffering from absolutely horrible high beams and pretty bad low beams thanks to the Americans dictating it had to have quad rectangular sealed-beam bulbs instead of the excellent European E-Code reflectors.

    I installed sealed-beam to H4 conversion bulbs and have rectified some of the absurdly bad high beam problem, but the beam pattern of these conversion units is lousy and installing brighter bulbs will just mean a larger lousy mess.

    Incidentally, this H1 bulb you speak of (from 1962) only became legal in the United States (and therefore Canada) in 1997.

  5. Changes Says:

    Our roads are lit enough that I find myself forgetting about high-beams completely. I only ever use them to signal to incoming cars when I see a speed trap... which is technically illegal, but if they ever fine me for that I'll put a frame around the slip and set it on my wall for all to see.
    (Lest you think that I'm a speed demon, there are places around here where limits are absolutely ridiculous; it's those I have a problem with, not the traps on the highway.)

    FuzzyPlushroom: can't you replace your bulbs with better ones while staying inside the legal limit?

  6. FuzzyPlushroom Says:

    Changes, Probably - that's gonna be the next thing up. Part of the problem is the yellowed polycarbonate lenses.

    evilspoons, the Mystake (Mondeo) is a '97... hmmmm.

  7. rocketfire Says:

    Does this mean North American BMW X5's don't have unbearably bright HID headlights? And the sporty merc's aren't blinding all oncoming traffic. Does it mean even fools in regular euro car can't drive day and night in North America with their foglights shining all over the place?

    If so then count your blessing....unless you are a tosser in an X5, in which just ef-orf with your rediculous low beams.

  8. Stark Says:

    Hmmm.. there are plenty of vehicles with HID beams here (California) - those blue eye-searing lights are a menace I tell you.

    That being said I've been trying to find a retrofit HID bulb for my motorcycle - where I actually want to cause oncoming drivers some annoyance. An annoyed driver is one who's aware of you after all. I've already wired up 2-watt leds (8 of em) into my taillight and rigged em to flash from normal to "holy cow, what the hell was that?!?!" for the first 10 seconds after I engage the brakes. I wish I could leave 'em on super bright but the cops frown upon tail lights brighter than many headlights. Ah well.

  9. Daniel Rutter Says:

    A lot of the worst HID headlights are cheap retrofit kits, which aren't aimed properly. A proper HID headlamp may look a bit weird - classically, that freaky blue flash at certain angles that makes your "Aaah! A cop car!" neurons fire - but it shouldn't be any more annoying for other drivers than an old-fashioned filament bulb. But lots of people have mis-installed HID lamps that're too bright at other angles.

    (Just setting them up for a plain symmetric beam is actually likely to be illegal; low-beam headlights are actually meant to give an asymmetrical beam, illuminating less of the side of the road with oncoming traffic. So they favour the left, here in Australia; the right, in the USA. This is one of the several things that can bite you if you insist on driving a left-hand-drive vehicle in a right-hand-drive country, or vice versa.)

    The popularity of SUVs is another problem, here; if you're not driving a vehicle that's just as tall as they are, your eyes will probably be below their headlights, which makes glare an issue again.

  10. Jonadab Says:

    > How I loathe US headlight laws and how they
    > affect me in Canada.

    And here I was thinking how unnecessarily bright US headlights have gotten these last few years, to the point where you never actually need to turn on your high-beams even on unlit country roads. Just the regular beams, if your car was made any time in the last two and a half decades or so since the popularization of halogens, are enough that you can see objects *in color* at a quarter of a mile (provided the road is sufficiently straight and flat that you have line-of-sight down the road to anything that distant, which in some parts of the US goes without saying, and in other areas would be rather unusual).

    IMO, if you think US headlights are too dim, you probably should make an appointment with an ophthalmologist and get yourself checked for cataracts.

    > those blue eye-searing lights

    Those things *definitely* ought to be illegal for low-beams. (For high-beams it isn't as much of a problem, provided the law against shining the high-beams into oncoming traffic is enforced. You seldom need high beams in central Ohio, because there's almost always oncoming traffic, but in places like northern Indiana you do use the high beams sometimes, and a bit of extra brightness doesn't really hurt anything there, even if it isn't strictly necessary.)

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