Lumintop EDC18 XP-L HI strange led afterglow

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prodal
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Lumintop EDC18 XP-L HI strange led afterglow

Hi,

when running the light in lower settings or ceiling mode i get an uniform afterglow on all 3 leds for like 5 seconds.

But when I run it in turbo mode only 2 of 3 leds show an afterglow.

 

First I suspected the third led doesn't run full power in turbo mode but i'm not quite sure.

 

Is there something wrong with the light or is there a technical reason for the light to behave that way?

 

Jerommel
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XP-L (HI) has a bit of afterglow from the phosphor.

So does XP-G2, by the way.

SammysHP
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I noticed this as well with several lights, but I do not mean the afterglow of the phosphor. It stops when you remove power. There is a tiny leakage current in some drivers. Maybe it is a property of the FET or the capacitance in the system is enough.

Different flux bins might explain the uneven brightness. One way to “measure” it would be to burn something and check if the burned area looks even (but might cause damage to the lens) or to use a camera with a filter (if necessary).

Xandre
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The 3s led looks like not in the center.

Different Forward Voltage are a reason to make different brightness in low-

thisnameisvalid
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LEDs basically work by having a layer of phosphor over a blue diode. When the blue photons strike the phosphor molecules their electrons are excited up to a higher energy level. The white light is produced when these electrons drop back down from this energy level, emitting a photon. The wavelength of the photon depends on the particular molecule as the phosphor is basically a big chemical soup designed to produce white light.

Not all the electrons drop back down immediately, so what you’re seeing is the residual ones dropping down energy levels and still producing light.

If there’s leakage current as mentioned earlier the LEDs will glow constantly. Its normal for them to glow for a short time after turning off; warm & high CRI emitters tend to glow longer / brighter because they have more phosphor.

prodal
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Thanks for clearing that up with the phosphor and afterglow.
But in low and top ceiling mode, all 3 leds show the same lenght and brightness in the afterglow.
Only after running in turbo mode only 2 of them show afterglow.

So I was expecting something driver related as SammysHP said.
The brighness in lower and medium modes seems very even when looking into the light with sunglasses. I don’t have a ND-Filter tho.

Xandre wrote:
The 3s led looks like not in the center.

Different Forward Voltage are a reason to make different brightness in low-

Yes the right led in the picture is off centered .