Decreased XP-E performance

kosPap

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hi all!

during the CPF crash I was experimenting with XP-E dropins because of its throw characteristics...

My materials were
Cutter 14mm R2 WC
noname R2 from a cheap dropin

with both leds I got decreased perormance....about 20% lower than the XRE Q5

for example at 1.2A i got as much light as with the Q5 at 1A....

since we are talking P60 modules, i also eliminated the case of the LEDs not being properly positioned/focused and loosing light from spilling below the reflector (I used an opened up hole reflector)

same thing with both LEDS, in 1A and 1,2A currents.....

the phenomenon is persistent and uniform...

so what gives?
 

bshanahan14rulz

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I blame heat. I love P60, but I know I will have to switch to a single-purpose host one of these days if these LEDs keep getting so beefy.
 

kosPap

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no way it is heat...measurements were taken at 15secs

I wonder could the XPEs be -in general- actually out of spec?
 

sn0wBLiND

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The difference between XP-E and XR-E is the package. I don't think the thermal impedance between those packages is that significant at those drive currents so the only thing left is optical characteristics.
I bet that 20% you are looking for is just being distributed somewhere else in the beam.
 

qwertyydude

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Is the reflector made specifically for the xp-e? It sounds like no because you had to open up the hole to use it. An xr-e reflector does not throw properly with xp-e.
 

kosPap

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sn0wBLiND, no way, my lumen measurements are done in a box....

Is the reflector made specifically for the xp-e? It sounds like no because you had to open up the hole to use it. An xr-e reflector does not throw properly with xp-e.

actually two different reflectors were used of different make BOTh XP-E ones...I mentioned opening up the hole to explicity aviod light being lost under the reflector.
 

qwertyydude

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Then the only thing I would say is there are optical characteristics messing with you. The XR-E throws more of it's light directly outward because of its lens design so it may encounter less losses in a reflector. Plus a box is not an integrating sphere, it's tough to sort through the variables beam shape can introduce to readings.
 

kosPap

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yep but....such a drastic change in beam width cannot atain a 20% difference, at least in my lightbox....

for exmple it is more than a maglite's difference from flood to throw....

go figure.....
 

SemiMan

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20% sounds like a lot, but even LED manufacturers have trouble testing to good tolerance with very sophisticated setups. Changes in how the light hits the wall of your box at different angles, etc. can make surprising differences. Can you post a picture of your box?

At those currents, even 15 seconds can add some error as well especially with the XPE as it has almost no thermal mass of its own unlike the XPE.

I expect it is a combination of many factors which are contributing. When you take into account binning error, a good Q5 can put out more light than poor R2.

Semiman
 
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