Bogus Dive Light Claims?

[eelnoraa]

A few years ago, I did quite a few light output measurements with equipment s that I have at work. Most exaggerates the actual output. They often quote the theorotic max output of the LED from diode datasheet instead of the output during real operation. There are of course some are quite accurate to the real operation, and there are those that flat out lie including one of the bigger brands.

Sorry, I didn't finished typing before when I was called on a diaper duty.

For this Ocrean Quest 3600 light, let's study the spec and see if that can even be realistics.
1. output of 3600 lumen, by 4 Cree XM-L2 diode. So each need to be responsible for 900 lumen. From cree data sheet, which I have previous learned that they are actually on the conservative side, if you use U2 bin, drive 2A into the diode, you can be a minimum of 730 lumens out of the diode. I will take benefit of doubt, the max can actually read 900 here. So yeah, 900lumen per diode is possible.

2. Power consumption and supply limitation. To get 2A into each diode, the voltage across the diode needs to be about 3.2V. Total wattage is 3.2V x 2A x 4 diodes = 25.6W. Using 2x 18650 to power this, it is most likely x2 series x2 parallel. This mean the 18650 needs to supply 4A in sustained state. 18650s that are capable of this don't have too high of mAh rating. I think 3400 would probably be the high end of the mAh rating. Total energy will be 2 x 3.7V x 3400mhA = 25.16 Joule. With 100% efficiency, this will sustained about 1 hours of run time at most.

However, things don't work like that. With 4A draw on 18650, the battery efficient is probably at best 80%. The efficiency of a very good switch regulator is say 95%. So that 1 hr of theoretical calculation becomes 45 minutes to fully deplete the cell. But also keep in mind, 18650 can't supply its peak output throughout the entire range of its charge especially at 4A drawn. From personal experience, you will be lucky to get half of that run time with 4A drawn, then the rest of the run time will be with power reduced.

So is the lumen and runtime possible? Yes, but not with 2x 18650 with current state of Li-on techhighly. The bogus claim is the max possible lumen output and an average case of runtime, but they really don't happen at the same time. this is a very common practice from Chinese light makers. They technically didn't lie, just slimy advertisement.

There is at least one. kind of big brand out there, which I don't want to name, who actually flat out lie. They use 1 Cree LED and claim to have 3500lumen of output.

 

[tbone1004]

A few years ago, I did quite a few light output measurements with equipment s that I have at work. Most exaggerates the actual output. They often quote the theorotic max output of the LED from diode datasheet instead of the output during real operation. There are of course some are quite accurate to the real operation, and there are those that flat out lie including one of the bigger brands.

can you post that data?

 

[DavidFL]

The linked wetestlights stuff is interesting. Is there a common reason for the big falloff(s) in intensity in relatively short runtimes for some of the lights? Is it brand/tech stack/battery tech dependent?

 

[tbone1004]

The linked wetestlights stuff is interesting. Is there a common reason for the big falloff(s) in intensity in relatively short runtimes for some of the lights? Is it brand/tech stack/battery tech dependent?

the drivers are chosen to maximize burn time as opposed to constant output

 

[Manatee Diver]

So we're clear: xtar is a Chinese company.

Lots of great companies out of China, and quite a number of bad ones too.

There are a lot more claims made than met in regards to lights. Light Monkey, Dive Rite and a few others do really well.

China can deliver quality products, Xtar, Anker, Aukey, DJI, and a number of other Chinese brands bring direct to consumer prices with quality because they built an actual brand up. But when contracted by a third party, or dealing direct as a generic company Chinese brands can and do skimp on quality. And that isn't just to screw Americans, they do it to their local consumers, for example DJI great company in the US, but they sell that low quality items that Americans wouldn't tolerate to the local Chinese market.

 

[eelnoraa]

can you post that data?

If you search this forum for my post on light, you can find some. I tested HOG Morph, DGX600, my trusted HOG 21W HID, Halcyon Focus, UWLD (the low end version) two chinese makers which I don't remember their names, a few Hollis 3C LEDs, plus a few more.

My conclusion back then was this. Halcyon, UWLD, Hollis 3C handheld were pretty honest about their numbers. Others are not so accurate. Single Cree LED handheld (1-2 18650) produce about 300-400 lumen at best. Most are actually below 300 at steady state. Cree with 26650s can get to about 600-700 lumen. I haven't seen any single Cree LED that can do 1000 lumen regardless of the battery pack in actual test. LED gets very inefficient when driven hard.

 

[eelnoraa]

The linked wetestlights stuff is interesting. Is there a common reason for the big falloff(s) in intensity in relatively short runtimes for some of the lights? Is it brand/tech stack/battery tech dependent?

the drivers are chosen to maximize burn time as opposed to constant output

If you are referring to LED25 light fall off at the first 5-10 minutes, that is because he battery. When you fully charge any Li-on cell and start a drawn, it initially can push out a much higher ampage. then it reaches it steady state which is a function of the current drawn, and steady state number is usually quite a bit lower than the peak due to internal impedence increase

 

[Eric Sedletzky]

I’ve been reading this stuff trying to understand some if the technical talk.
One question for anybody that might know.
I have a DRIS 1000 lumen led hand held back up light. Seems pretty bright and so far has been pretty good. Does it have 1000 lumens as advertised or is this also BS?

 

[eelnoraa]

Also keep in mind, the perception of brightness to human eye and lumen number does not necessary correlate. Sometime they don't even go on the same direction. The best example I can give is Light & Motion Sola. They actually live up to the lumen claim by having many lower intensity LEDs. They don't appears to be as bright as say 21W HID even if actual measurement can be higher. Human eyes are NOT good judgement on lumen.

 

[eelnoraa]

I’ve been reading this stuff trying to understand some if the technical talk.
One question for anybody that might know.
I have a DRIS 1000 lumen led hand held back up light. Seems pretty bright and so far not much out there that can beat it for a hand held that I can find. Does it have 1000 lumens as advertised or is this also BS?

DRIS1000 3C handheld measures about 250 lumens. I have this light and mesaured it. Typical alkine C cell can sustained about 1-1.5A of draw. The LED can therotically output 1000 lumen if you put 3+A into it, which C cell can't do. And not to mention anyone put 3A into that Cree, what will be the service life. You can decide if this is BS or not.

What you see also says a real 250 lumen is actually lot of light for average nigh fun dive.