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I am working as a night delivery driver and when its dark and/or rainy it's almost impossible to read many of the house numbers/names I am looking for.

I've heard of Maglite and in fact my friend has a large Maglite which is 680lm and very powerful but it cost him a fair bit and uses huge batteries.

I look on auction website and see ones boasting 900,000 lumen output! (for about £5 :D) I then google 'worlds most powerful flashlight' and it seems one made by 'Wicked Lasers' is considered one of the most powerful at 4,100 lumens. (https://www.wickedlasers.com/torch)

So why on auction site are they allowed to state 900,000 lumens. And how can i trust the output specs on any advert? (is there any other spec I should be checking)?

Really need it soon, and I need to be able to see stuff that is about 20-30 metres away in heavy rain at night.

Any help would be greatly appreciated. Thanks

(Ps. I could put links showing the adverts boasting 900,000lm but didnt want to put their links anywhere in case they are a scam)

Additional Edit:- Well I have continued looking and the specs vary massively. This one I am thinking of buying boasts 20,000 lumens and 500m range. But it only takes 1x AAA battery ??!?!? - Surely this cannot be 20x more powerful than a top Maglite? https://www.ebay.co.uk/itm/Tactical-20000LM-L2-Zoomable-LED-Flashlight-Rechargeable-battery-Torch-with-BOX/322609536378?epid=16031184130&hash=item4b1d06dd7a:g:SwQAAOSwmcNdIJWc)

Conclusion: For what it's worth I decided not to buy a 'No-name' brand. And after finding this one at Toolstation: https://www.toolstation.com/ledlenser-tt-police-tactical-torch/p41307 I realised their pricing is actually very competitive. It is a few quid cheaper in Toolstation than the same torch is on Amazon or ebay. I can just go into the shop and buy it today :D

I am happy now, thanks again all you guys. PS. You have inspired me to begin learning electronics as a new hobby too

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closed as off-topic by Wesley Lee, Chris Stratton, Michael Karas, Oleg Mazurov, Justin Sep 17 at 19:28

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    \$\begingroup\$ By any chance is it actually 900,000 candlepower rather than lumens? \$\endgroup\$ – 1N4007 Sep 16 at 13:37
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    \$\begingroup\$ Are you taking into account lumen vs lux vs candela? A standard 60W lighbulb easily produces 800-1000 lumens. \$\endgroup\$ – EasyOhm Sep 16 at 13:38
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    \$\begingroup\$ They lie. It's as simple as that. \$\endgroup\$ – Janka Sep 16 at 13:45
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    \$\begingroup\$ My quick first impression from that ebay listing is: "Lies, lies, lies". \$\endgroup\$ – Jack B Sep 16 at 13:45
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    \$\begingroup\$ There's no way it's 900,000 lumens. If, somehow, it is, then you don't want it for your stated purpose because it's a directed energy weapon, not a flashlight. Here's a 72,000 lumen handlamp for reference: youtube.com/watch?v=-vgNh3fLxJc \$\endgroup\$ – Perkins Sep 16 at 23:44
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Well in your eBay-Link they are providing enough material to debunk themselves. They say they use a Cree XM L2 LED. So let's just look up what that thing can output.

Datasheet XM L2 LED and we see: even if it is driven with 2000 mA - which is quite the stress on the battery - it outputs 600 lm.

And they kindly provided a picture showing that they only use one LED and not multiple.

So they are lying or they measures the first production batch in unison and forgot to say they used 400 of these things.

Generally, you can expect around 100 lm / W and a handheld device is probably using 10 W maximum (okay might be 20 W or so with a good battery), so anything beyond 2000 lm is just unrealistic.

If they tell you the 4000 mAh battery will last 6 hours, you can calculate the wattage:

4000 mAh / 1000mAh/Ah * 3.7 V / 6 h = 2.5 W.

So 250 lm would be a realistic guess for the brightness. And yes, the 4000 mAh are faked as well - currently 18650 LiIon are around 3200 mAh maximum.


Okay, so how does the "brightest torch" from wicked lasers hold up with these estimates?

They claim 4100 lm using a 100 W OSRAM halogen bulb. The datasheet of that bulb tells us it emits 2800 lm. (Edit: the reflector does not affect the luminous flux, sorry about my mistake I often mix up the luminous units) I'm not really sure how they arrive at the 4100 lm figure - with 100 W it would be 41 lm / W, which is unrealistic high for a halogen bulb. So probably a bit of overadvertisement to stay with the claims of the cheap competition.

What about the power of this thing? They claim 100 W which sounds ridiculous. But they use 4 18650 batteries in series and give a low estimate of 20 minutes lifetime. Sadly the capacity is not given, but this is a really high current application, so the capacity will be a bit smaller - I guess 2500 mAh for a high quality cell.

4 * 2.5 Ah * 3,7 V / 20min = 111 W

So the math actually checks out and I think that it does what they say.

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    \$\begingroup\$ wow thanks man. Makes a lot of sense that! I really need to learn about this stuff more as I do find it very interesting and wish I could deduce this myself rather than asking help from you kind folk. \$\endgroup\$ – Big T Larrity Sep 16 at 13:58
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    \$\begingroup\$ @BigTLarrity well the faked specs aside, they usually come with bad engineering and you might end up with a burning torch (which will briefly output more lumens). \$\endgroup\$ – Arsenal Sep 16 at 14:11
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    \$\begingroup\$ As a flashlight fancier I really appreciate this answer showing how to do the arithmetic given available specifications. \$\endgroup\$ – davidbak Sep 17 at 2:20
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    \$\begingroup\$ Mostly very good answer, however the part about the reflector is incorrect. The lumen figure is luminous flux, which is the total output of the lamp, and does not change whether it’s dispersed in all directions or “concentrated” in a small cone. The figure that would change is the luminous intensity, which is measured in candela. \$\endgroup\$ – jcaron Sep 17 at 6:55
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    \$\begingroup\$ I think there are a few torches which measure battery and LED temperature and dim after a few minutes at maximum brightness if/when the temperature reaches unsafe levels. \$\endgroup\$ – Michael Sep 17 at 9:20
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TL/DR: It's a scam.

Long answer:

Current LEDs that work well in flashlights have luminous efficacies in the 100-200 lumen/Watt (roughly, not factoring in driver losses etc).

Thus a 900 000 lm flashlight would require 4500-9000W of power... thus a huge battery and about the same cooling fan as a hairdryer.

Also LEDs for flashlights are usually rated between 1 and 10W and a common LED power for a flashlight is 3W. So if you look at the flashlight and only see ONE LED in it, and it is rated for more than 1000-1500 lm, expect trouble!

Then you can check for battery lifetime. An AA 1.2V 2500mAh alkaline can deliver about 3 Wh (Watt Hours) of power which means 3W for 1h or 1W for 3h, you get the idea. So a flashlight with 300 lumen (about 2-3W) with a battery life of 2 hours on 2 AA batteries sounds good. A bit optimistic considering AAs lose capacity at high current but... not in scam territory. If it is advertised for 1000 lumen and 10 hours battery life on 2 AAs, then... you know something's off!

Lumens describe the total amount of light out of the flashlight. Candlepower (candela) is a misleading number as it describes lumen/steradian, ie light flux in the beam. The same LED, same lumen, will have much less candela with a flood optic than with a tight beam optic, because the tight optic concentrates the light more. Using candelas is a good way to get impressive numbers which look good!

Also cheap flashlights tend to have gotchas, like no spring contacts for the battery, so when you shake it a bit it will turn off or switch to blinking mode.

In other words, go to a flashlight geek review site and pick one by a good manufacturer.

So why on auction site are they allowed to state 900,000 lumens.

How is ebay supposed to check?

If you want a good light, first decide on the batteries you want. 18650 Lithium are better, especially in the cold, but require a specific charger. NiMh AAs are more convenient, but lower capacity.

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  • \$\begingroup\$ Thank you for the help here mate. I had badly worded by question with the 'Why are they allowed by ebay to state xyz lumens....' of course I didn't expect ebay to check. But I thought maybe if they lie like this there would be more 'calling-out' or 'shaming' of such practices by experts such as you guys \$\endgroup\$ – Big T Larrity Sep 16 at 14:01
  • \$\begingroup\$ Ideally I would like a torch with rechargable AA. And it would be perfect if I can somehow charge it via USB (even if extremely slowly charged). But you all have given me much food for thought and more info to fight against the tidal wave of BS that is eBay :D \$\endgroup\$ – Big T Larrity Sep 16 at 14:03
  • \$\begingroup\$ Yeah, I wouldn't buy a flashlight on ebay... especially a no-name Chinese product... there are TONS of scams. \$\endgroup\$ – peufeu Sep 16 at 14:08
  • \$\begingroup\$ sadly i think you are right, but much more expensive for me to buy locally and the shops do love to overcharge for everything. I'd love to find a reasonable one on ebay but probably will give up and by from Toolstation or something :| \$\endgroup\$ – Big T Larrity Sep 16 at 14:13
  • \$\begingroup\$ Check candlepowerforums.com they have reviews of cheap flashlights. Also other flashlight geek forums. Some people measure the actual lumen. \$\endgroup\$ – peufeu Sep 17 at 15:15
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Note that in some regions, a comma is a decimal separator - the manufacturer could claim that the nominal light output is 900 point 000 lumens. Obviously, there is questionable faith in gaming such conventions.

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  • \$\begingroup\$ lol , after learning everything i have read here, i really doubt it is even 900 lumens. Ended up buying one locally with 280 lumen and it does the trick :D \$\endgroup\$ – Big T Larrity Sep 17 at 10:51
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    \$\begingroup\$ "specification suggested that the light output is calibrated at 1ppm tolerance or less. Wouldn't buy again" :) \$\endgroup\$ – rackandboneman Sep 17 at 13:10
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The 900000lm figure is just a lie. The maximum amount of lumens (i.e the turbo mode) you can expect depend on the LED, the driver, the battery chemistry (Alkaline, NiMH, lithium primary or Li-Ion) and to a lesser extent on its discharge rating. The size, mass and design of the flashlight affects how long that maximum can be maintained without overheating. Flashlights using standard 5mm leds won't have much output. To obtain high output you need high power leds like the Cree XM or XP series, Luminus SST20/40, Nichia 219/319 or Samsung LH351D, to name the most popular emitters. While COBs are feasible they are not as popular in high power flashlights for their lower luminosity per area and often higher voltage requirements, except on some flooders and worklights.

For a tube light using a single 18650 or 21700 that fits easily in a pocket you can expect at most 1600lm in turbo mode but it will need to step down quickly to 600-800lm to avoid overheating. See for example this Convoy S21A review for that behavior, that's one of the highest output single LED flashlights in that size. Some small flashlights like the Emissar D4 or the BLF FW3A can obtain higher turbo output using multiple high power LEDs (thus being called triples or quads) but they need to step down faster, often in matter of seconds to avoid overheating. Also using multiple LEDs doesn't allow as much intensity (throw) as a single LED for the same head size.

Larger flashlights can use LEDs with multiple dies like the Cree XHP70.2 or many high power LEDs. Examples of that are the Convoy S11 (single XHP50.2, 26650 battery), Convoy L6 (single XHP70.2, 2x26650 batteries), the Sofirn SP36 (4xXP-L2 or 4xLH351D, 3x18650 batteries) or the Emissar D18 (18 SST-20, 3x18650 batteries). Their larger mass and area allow them to maintain their higher output for longer but none of them fit easily in a pocket.

One thing you need to take into account is that the ANSI flashlight standard can be easily abused. The output is recorded at 30 seconds while the runtime is the time until output drops below 10% of that stated output, so some brands game the standard by dropping the output to near 10% after 1 or 2 minutes. Furthermore the throw is the distance where the illuminance drops to 0.25 lux, while many people argue that you actually need at least 1 lux to see clearly.

Another thing to take into account is that batteries specifications often are faked as well. As September 2019 any 1.2v NiMh AA over 3000mAh (over 2500mAh if low self discharge), 3.7v Li-Ion 14500 over 1000mAh, 18650 over 3600mAh, 21700 over 5000mAh or 26650 over 6000mAh is faking its capacity. See HKJ's site for batteries reviews. Batteries with fake capacity often are junk or worse, a fire hazard.

Zoomable flashlights have some advantages like an uniform beam in flood mode and no spill but also some disadvantages like non uniform beam in focus mode (Coast and Led Lenser avoid that issue in focus mode using a patented mechanism but still have some artifacts in intermediate modes), less waterproofness and reliability as well as larger size because of the zooming mechanism. Some consider that no spill is more a disadvantage rather than an advantage. For these reasons many flashlights enthusiasts prefer fixed focus flashlights.

Personally I would recommend you to make a Reddit account, go to r/flashlight and fill the recommendation form.

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First, 680lm is a lot. It is the equivalent of a 50 watt incandescent bulb, but in a spotlight. That wasn't even possible in flashlights until LED.

Your question about the MagLite...

  • It makes 680 lm because that's a sensible amount of light (i.e insane) for a tactical flashlight. It is a good compromise between brightness and battery life.
  • It uses huge batteries for a bunch of really good reasons.
    • D-cells have five times the capacity of AA cells and 10 times the capacity of AAA cells. That means powering that very bright 680lm for 12 hours - easily a full shift. You would have to change AA 4 times per shift. AAA, 9 times.
    • Being so large, the battery dims quite slowly, so you can defer the change until you're back at the truck.
    • D-cells are cheap - which should appeal to a miser. They are twice the price of AA but last five times as long.
  • MagLite's entire gig, what they are famous for, is making the flashlight so tough it can double as a nightstick. Ideal for intimidation + deniability! The best way to create this heft is with heavy batteries.

The other lights

This is really simple. LEDs make 100 lumens per 1 watt. Assuming you want to make it through a whole shift, you need 8 watt-hours per 100lm.

A common AA cell is 4 Wh. An AAA is 1.8 Wh. A D-cell is 18Wh. An 18650 is 11 Wh. A lantern battery is 66 Wh. (Actually that seems low).

So your 680lm Maglite needs 55 watt-hours. Four D-cells can do that no problem.

Your 2000lm magic-light needs 160 watt-hours. How the hell you going to get that? That's 9 D-cells or 15 18650's. It's a frickin' railroad lantern at that point.

A 20,000 lumen light for a work shift needs 1600 watt-hours of battery. This is not liftable; it's a backpack.

A 200,000 lumen light - we're way past batteries at this point.

So no, none of those crazy lights are going to happen, even if they were real.

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  • \$\begingroup\$ If you're using it regularly, you're going to want rechargeables. I assume NiMH D cells are available but usually you only see AA and AAA supported by modern chargers. \$\endgroup\$ – Peter Cordes Sep 17 at 8:52
  • \$\begingroup\$ For comparison with this answer, 1600 Wh is about 133 Ah at 12 V. A quick web search turned up a 100 Ah 12 V car battery weighing about 22 kg. That would almost last the 20,000 lumen light through an eight-hour shift. Of course, car batteries typically don't take well to deep discharge, so you'd probably want to limit the discharge to maybe half capacity at most, at which point you're looking at 2-3 hours of runtime for that light in return for hauling around over 20 kg of battery. Or approximately your own body weight in batteries for a full eight-hour shift at reasonable discharge levels. \$\endgroup\$ – a CVn Sep 17 at 11:24
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    \$\begingroup\$ @PeterCordes A quick Amazon search turns up a bunch of different NiMH D-capable chargers in the price range about $20 and up (and one or two that are even cheaper). So while it's true that lots of cheap chargers these days only physically support AA/AAA, larger chargers are definitely available and not even particularly expensive for basic models. Some of them even advertise support for typical LiIon battery form factors like 18650. \$\endgroup\$ – a CVn Sep 17 at 11:25
  • \$\begingroup\$ @aCVn Lead-acid is near the bottom of recharable batteries in terms of watt-hours per kg. Comparing to, say, the 434W·hr Anker Powerhouse 400, that backpack would probably be around 15kg total (including all the casing, electronics, etc.) \$\endgroup\$ – derobert Sep 17 at 20:33
  • \$\begingroup\$ @derobert Indeed. I didn't have a lot of time to look around, which was why I went with what I could find quickly for high-capacity rechargable batteries. I certainly didn't mean to imply that what I found would be the best choice (indeed, often the first hit is a poor choice, especially when you're casting a wide net). There are other reasons as well why a car battery would make a poor choice for such a project. \$\endgroup\$ – a CVn Sep 18 at 13:58
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Blatant false advertizing on ebay is, well, not unheard of.

As for lumens:

A good modern LED makes ~100 lumens per watt. Theoretical limit is somwhere 650 lm/w but the current technology is not anywhere near. And those 100 are the LED itself. The reflector and the lens get their share, so out of the device you will probably get 70-ish lumens per watt. This also means for every 100 lumens you have 0.8 watts heat to dissipate.

900000 lumen LED setup will need some 9000 watts for power and some 7200 of them will become heat - enough to heat a rather large house in winter.

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    \$\begingroup\$ +1 for that fiirst sentence :) \$\endgroup\$ – Fattie Sep 17 at 11:34

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