Need help calculating lumens

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klrman
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Need help calculating lumens

Hello, newbie here.

How many lumens would a 240w flashlight put out with 24 Cree T6 LED's using four 26650,  5000 mAh batteries?

Edited by: klrman on 11/07/2016 - 22:52
JockRobbins
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Well I’m new but I know my stuff. 250 watts, it is not. You’d be lucky for it to be 60. It’ll be bright,but not 13,000 (lol) it’ll be under-driven and basically crap. I estimate 3500, if it’s this one ;

https://www.aliexpress.com/popular/led-flashlight-24-led.html

I would say avoid it – buy something like the Q8 that is in its r&d stages here on BLF – you WILL get quality – and actual stated lumens. I believe 4000 is the target.

klrman
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Thanks for replying!  Yes, that is the one from aliexpress.  I contacted them a few times, but they would never disclose any info about the driver!  They always pretend they don't know what I am talking about lol.  They also claim 30,000 lumens.  I don't know how these guys get away with all that false info.

JockRobbins
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Lol that would literally require 30-35 LEDs fully driven, and literally impossible with 4 LiIon batteries. And it’d need kilograms of copper for heatsinking.
They get away with it, because literally 99.995% of any given population don’t know better. And that blows. Look around here bud, and you’ll be blown away with what these guys and girls know. Almost 4000 posts – just for the Q8 – I cannot wait to grab one, knowing that no one I know would know what quality and workmanship/materials are in it. Like my 2X Shooter – unassuming – if you don’t know what you are looking at.

klrman
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I used to be one of the 99.995% lol.  Thanks to you I am now following the Q8 thread.  Can't wait to get my hands on one either.

JockRobbins
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You won’t regret it if you buy one. I can guarantee you’ll be impressed with the way it’s made. And unlike generic s**t, it will not let you down, start to flicker, or just one day putt out. Even if the final price were twice what the objective is, I’d still get one. It’s not often such a thing is ever produced – get in to it.

wle
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4 li ions would (26650) put out maybe 25 amps, say 90 watts, which would more or less fully drive about 12 big leds, so maybe 9000-15000 lumens.
for about 5 minutes.
and will be boiling hot in about 2 minutes.

JockRobbins
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wle wrote:
4 li ions would (26650) put out maybe 25 amps, say 90 watts, which would more or less fully drive about 12 big leds, so maybe 9000-15000 lumens. for about 5 minutes. and will be boiling hot in about 2 minutes.

I can assure you the light the op is looking at is nowhere near 9000 lumens !
The potential is there – given some huge mods. But most certainly not in stock form. Thumbs Up

wle
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Why not though? It has 24 LEDs, seems like it could do that before the batteries died or the head melted.

Wait, 24 amps from these giant batteries, would be 6 fully driven leds, so 6000 lumens maybe?

Enderman
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wle wrote:
Why not though? It has 24 LEDs, seems like it could do that before the batteries died or the head melted. Wait, 24 amps from these giant batteries, would be 6 fully driven leds, so 6000 lumens maybe?

 

Because the drivers in those flashlights do like 300ma per LED or something ridiculously low. The LEDs light up, and there are many of them, but they are all working far below their rated output.

Hey, how are you? :)

wle
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this one..

https://www.aliexpress.com/item/Aluminum-alloy-led-flashlight-Hunting-ex...

..claims to have 24 XML-T6s though.. his link is to a generic search page so we may be talking about 2 different lights.
this one costs $133

wle

klrman
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If it was even 9000 lumens it would be a good deal but ask any of the sellers for a data sheet of the driver and none of them will give it to you.

JockRobbins
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wle wrote:
this one..

https://www.aliexpress.com/item/Aluminum-alloy-led-flashlight-Hunting-ex...

..claims to have 24 XML-T6s though.. his link is to a generic search page so we may be talking about 2 different lights.
this one costs $133

wle

That is the exact light he’s looking at. I linked it further up this thread, not him, and he confirmed it was that first one on the page.
I will repeat what I said prior – it is not 9000 lumens, but with the RIGHT MODS it could be. Stock, as also mentioned, will be waaaaaay under-driven.
Please buy one and do some tests !!! Smile you will be disappointed!

unknown00101
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JockRobbins wrote:
wle wrote:
this one..

https://www.aliexpress.com/item/Aluminum-alloy-led-flashlight-Hunting-ex...

..claims to have 24 XML-T6s though.. his link is to a generic search page so we may be talking about 2 different lights.
this one costs $133

wle

That is the exact light he’s looking at. I linked it further up this thread, not him, and he confirmed it was that first one on the page.
I will repeat what I said prior – it is not 9000 lumens, but with the RIGHT MODS it could be. Stock, as also mentioned, will be waaaaaay under-driven.
Please buy one and do some tests !!! Smile you will be disappointed!


It has Latticebright LEDs in the listing.

However, it very well could be 9000 lumens. There was a random generic ## LED flashlight, it may have been 12 or 15 LEDs I can’t recall exactly, similar Plunger design. In stock form it had essentially a direct drive driver and actually met or came close to the seemingly ridiculous specified output (Stock bypassed springs too iirc).

Granted that was 1 generic light among… a lot… The safer bet is definitely to spend money on flashlights that have been comprehensively reviewed.

JockRobbins
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If that light is purchased and confirmed to be 9000 otf lumens, I will eat my words, and my shoes!

klrman
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I purchased one just for fun. Different brand but still with the 24 T6's.  Will post pics when I get it in about 4-6 weeks.  I have a 6500 lumens LED work light and also a 13,000 lumens LED shop light, so I will get a fair idea about the lumens of this flash light when I get it.  I'm guessing it will be around 4,000 max but probably  less, but I only paid $54 so it's  worth the money if it works.  It's big enough to use for self defence if nothing else sealed

klrman
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JockRobbins wrote:
If that light is purchased and confirmed to be 9000 otf lumens, I will eat my words, and my shoes!

 

It should be here this week and I will post some pics of it's light output compared to my L6.  I'm guessing it will not even be as strong as the L6, but it does run on 4 x 26650, so I'm kind of of curious.  One thing I don't like is that it has 24 LEDs, so only 24 things could go wrong if they were not assembled correctly lol.

Enderman
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Chinese flashlight? You will probably get ~10% of the rated lumens Smile

Hey, how are you? :)

wle
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another thought is, what they may be trying to imply is “this light has as much light as a 250 watt incandescent bulb’‘, which i think would be about 2000-3000 lumens..

i have seen 1xAAA lights listed as ’9 watts’, which is of course total BS in terms of how much juice you can get out of a AAA battery.

the manufacturers or sellers cannot tell you, someone made up the ad copy and no one knows if they are trying to be dishonest, or just not telling you what the weird spec means.

wle

klrman
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I know their lumens etc is bogus, but since the flashlight itself is hefty with cooling fins, couldn't I put a much better driver in it and get around 9000lumens out of it?  Obviously using Latticebright LED, but I have a $5.00 flashlight with Latticebright LED and it is very bright. It is also underdriven.  I'm all new to this and my best flashlight is my L6, but this one looks fun to play around with just for kicks.  Still makes a good Christmas gift if nothing else.

 

Here is the one I ordered.  It takes 4 x26650 as recommended batteries.  Flashlight 24 LEDS 

They say in their description "with 24* XM-L T6 LED, the maximum Output bright can achieve to to be 30000 lumenbut obviously that is not what it  really outputs as they are only stating what max output "could" be.  Just hoping it's not going to be a dud with something like 2000 lumens  or less sealed

Lexel
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Just buy a Klarus XT11GT, Convoy L6, Olight R50 or other light that pushes 1500 or more lumens

They are compact and with groupbuy coupon not more expensive as those crappy multi emitter lights

klrman
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I have two L6's.

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If it’s big and has a decent reflector(s) then it’s got potential. “Bright” is relative, $50 should get you something bright“er” than an A6. Beam shape also affects apparent brightness since the same lumens in a tight spot will appear brighter than those same lumens in a floody beam.

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klrman
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That's very true, it is relative depending on so many factors.  Still curious how it lights up.  Finally got the seller to contact the manufacturer to get some real specs about the driver and LED. 

klrman
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I got the 24 led multi flashlight today.  L6 is brighter by about 20% give or take.  The multi seems to be around 3000 lumens.  I was guessing it was around 3000 before I got it but was hoping for about 5000+.  L6 is a much more solid looking flashlight too.  Way better built, rugged, refined and just an all around winner but I won't knock the multi as it looks in it's own way very cool, just not as bright or in the league of an L6 all around.

Lexel
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20% brighter to your eyes us more like 44% more lumens

The L6 has 3800 LED lumens on paper OTF it has about 3000 lumens

So your 12xT6 has around 2200 lumens

Just check the tailcap current multiple by 4V per cell and 80% efficiency of the driver

Most likely the driver runs each emitter only with 1A and dont have real Cree T6 inside so the efficiency is lower than the 120 L/W you would get from a real T6 XML

klrman
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The flashlight I have has 24xT6.  I will pull it apart tomorrow to see where it is really at, thanks.