XHP35: measured luminance and forward voltage

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Flintrock
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djozz wrote:
Flintrock wrote:
I actually think your method might be more accurate than an integrating sphere.
It all depends where your measurement errors and uncertainties are, both methods can be done less or more accurate. An example: the method of the OP and derived fine-tuning discussed later, heavily depends on a good quality well-calibrated luxmeter and requires some thinking about what the influence is of the diameter of the detector, while on the other hand in an integrating sphere method the luxmeter's calibration is not very relevant but the calibration light sources often are uncertain.

 

The lux meter is always relevant, in regards especially to how it samples the light spectrum.  I suspect for high bin led's this could maybe explain the high readings. 

Texas_Ace
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Flintrock wrote:

Throw per watt, the xp-l only needs to get 1336 (multiplying again by 24/30 as a rough figure) to be even.   Obviously the xp-l hi can beat that handily at 6A (24 watts).

Actually I doubt that, in my testing an XP-L HI is lucky to even match 1300 lumens. Highest I have seen so far a bit over 1200 lumens, usually closer to 1100-1200.

Which actually makes sense. Maxed out XP-L V6 models are generally around 1600-1700 lumens. The V2 is 28% lower flux bin, so thus by the math it should put out around 1200 lumens all else being equal.

EasyB
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Assuming we have an accurate lux meter, a potential advantage of this method is it might be easier to measure the absolute output without needing to calibrate the apparatus.

Texas_Ace, are those LED lumens or OTF lumens?

Texas_Ace
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EasyB wrote:
Assuming we have an accurate lux meter, a potential advantage of this method is it might be easier to measure the absolute output without needing to calibrate the apparatus.

Texas_Ace, are those LED lumens or OTF lumens?

OTF lumens for the most part, although I have not measured a known good HI model without a light yet.

Although it should be 28% lower then the V6 which seems to max out around 1700-1800 even at the emitter from others tests.

EasyB
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Based on measurements I’ve done, the XHP35 HI measured is closer to the dedomed XPL V6 1A in throw than most XPL HI V2 tints.

In an EE X6, I measured 70Kcd with a XPL HI V2 3B and 94Kcd with a dedomed XPL V6 1A. This was at direct drive currents with a 30Q cell, about 5.5A and 6A, respectively. With the X6’s reflector area of ~630mm^2, the effective luminances of the LEDs are 111 and 149 cd/mm^2, respectively.

Using the method in the OP I measured the luminance of the dedomed XPL V6 1A at 5.5A to be 141 cd/mm^2, which is consistent with the measurement in the X6. The XHP35 measured had a luminance of up to 135 cd/mm^2, which is significantly higher than the XPL HI V2 3B. The XPL V2 1A is another story though; I’ve measured it to be ~20% higher in lux than other V2 tints, but it has a noticeable bluish tint.

DB Custom
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In an unrelated topic the results from my build on the MaxToch Shooter 2X came up, thought the actual numbers from that might be relevant here.

This is copied and pasted out of robocop’s thread on the Shooter 2X…

“I took some measurements of voltage and amperage at the the emitter , and when I put the bezel/reflector back in it went on a little differently. So I checked lux again and got a surprise! 326.25Kcd for 1142.37M throw. Pretty much where the de-domed XM-L2 started out but with considerably more lumens. Sweet!

0.06A at 10.80V for ~89 lumens
0.55A at 12.22V for ~783 lumens
2.87A at 14.75V for ~2346 lumens

She’s singing along nicely!

And the LD-2 driver is very efficient apparently, with tail current readings at .06, .57 and 2.89A earlier (cells were higher charged then)”

(edit: used a clamp meter with a loop of wire between the negative lead and mcpcb for amperage, direct readout from the mcpcb for voltage, in the light)

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