Got my XT-E drop-in today; first impressions.

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RedForest UK
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Got my XT-E drop-in today; first impressions.

From KD, it is the 3 mode one and it came with a NANJG 1A max driver. This means that for those who accidentally ordered 5 mode it should be quite easy to change to 3 or 2 mode etc. The 3 mode one I have though seems to have been set by soldering the legs of one of the components on the inside, so harder to switch to a different mode set.

 

The LED itself is interesting, but in all honesty disappointing. Brightness is fine, it seems similar to my XP-Gs. But there is a lot of colour spread across the beam, way more than any XM-Ls I've seen, it gives the hotspot and spill a clearly yellowish corona with more blue central areas. The beam angle from the LED itself also appears to be very wide, it will not focus in an XP-G reflector and actually seems to work best with an old MC-E (very wide beam angle) reflector I had lying around.

 

On the whole, the drop-in seems well constructed and good value, and the new LED is a nice novelty. But I think the main selling point of these for CREE will be their low price/efficiency ratio (so big sales to light bulb/lighting array companies), rather than their accurate colour distribution or other characteristics desired for use in torches.

 

Of course I only have one sample LED, in a cheap drop-in, so these observations may not apply to all CREE XT-Es..

Edited by: RedForest UK on 05/09/2012 - 10:16
jacktheclipper
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...

What I do

 

brted
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Interesting. Kind of what I was afraid of. I think these will really help make efficient cost-effective LED bulbs. The key to efficiency is underdriving, but that means adding more LED's to get the light output you want. So they need to be cheap.

Glad to see a NANJG driver, though not so great at only 1A. Would another 7135 have killed them? Interesting that the 5-mode is probably more versatile since it can be soldered without taking the driver out.

sixty545
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RedForest UK wrote:

 

The LED itself is interesting, but in all honesty disappointing. Brightness is fine, it seems similar to my XP-Gs. But there is a lot of colour spread across the beam, way more than any XM-Ls I've seen, it gives the hotspot and spill a clearly yellowish corona with more blue central areas.

 

 

I got mine 5-mode today and I'm afraid I must agree with you. I did'nt notice at first but now I see the same bluish hotspot and I have a little yellow center in it.

I had great hopes that the new shape of the die (mountain-like) would get rid of the normal (for wide dies) yellow hotspot with bluish corona but they did it a little too much, I think so it's almost the opposite now.

The 5 mode is with the good old NANJG 47 (-A this time) with the small stars for programming on the back. It has the ATTiny13 (Hurrah) so I will modify with my own program.

The stock setup was:

Low-Medium-High-Strobe-SOS

20-120-360 lumens @ 56-330-1047 mA measured at 3.9V

16-106-360 lumens @ 42-280-1049 mA mesured at 3.6V

so the regulation seems fine (3x7135) but the PWM seems to vary with the voltage [ edited]

At 3.3V I measured 319 lumens on High (out of regulation).

So it seems to be a very efficient LED and it runs cooler than XP-G.

A pity with the mis-coloring.

I also got a "20"mm and a "14"mm star. They both gave 162 lumens at 350 mA so they are truly R5. The CCT was 5980K and they fit in bin 2B.

 

Boaz
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I wonder if these actually work better in a diffused material ..if the colors will all blend ..Do you have a decent diffuser ??  just curious

       καὶ τὸ φῶς ἐν τῇ σκοτίᾳ φαίνει καὶ ἡ σκοτία αὐτὸ οὐ κατέλαβεν

                            

       Dc-fix diffuser film  >…  http://budgetlightforum.com/node/42208

RedForest UK
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Yeah, with a diffusion lense you should get a nice overall tint I would imagine. My only diffused P60 lense is over a 2.5A regulated XM-L 5500k which I took out of my Olight S65 though and I'm not taking it off Wink

 

It's frustrating in the UK as due to the high humidity and cold nights you often find the inside of well-driven P60 lights fogging up. So when I get a very low humidity day (rare) I take my P60s out and re-assemble them outside. This normally fixes the fogging up issue but means I am stuck with leaving them assembled unless I really want to change out the drop-in or until another low humidity day..

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Wow I did not know that Sherwood is a rain forest???

 

I live in Oxford and never have any problems with my drop-ins fogging up.

 

Maybe you should try changing them in doors with the central heating on? Laughing

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Got mine today also. Exactly the same results with the OP reflector. The beam is a bit throwier than an XPG close to an XPE, but nowhere a replacement for an XRE. The ugly beam pattern can be easily forgotten outside though. It is a bright and throwy drop-in as is.
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sixty545 wrote:

RedForest UK wrote:

 

The LED itself is interesting, but in all honesty disappointing. Brightness is fine, it seems similar to my XP-Gs. But there is a lot of colour spread across the beam, way more than any XM-Ls I've seen, it gives the hotspot and spill a clearly yellowish corona with more blue central areas.

 

 

I got mine 5-mode today and I'm afraid I must agree with you. I did'nt notice at first but now I see the same bluish hotspot and I have a little yellow center in it.

I had great hopes that the new shape of the die (mountain-like) would get rid of the normal (for wide dies) yellow hotspot with bluish corona but they did it a little too much, I think so it's almost the opposite now.

The 5 mode is with the good old NANJG 47 (-A this time) with the small stars for programming on the back. It has the ATTiny13 (Hurrah) so I will modify with my own program.

The stock setup was:

Low-Medium-High-Strobe-SOS

20-120-360 lumens @ 56-330-1047 mA measured at 3.9V

16-106-360 lumens @ 42-280-1049 mA mesured at 3.6V

so the regulation seems fine (3x7135)

At 3.3V I measured 319 lumens on High.

So it seems to be a very efficient LED and it runs cooler than XP-G.

A pity with the mis-coloring.

I also got a "20"mm and a "16" mm star. They both gave 162 lumens at 350 mA so they are truly R5. The CCT was 5980K and they fit in bin 2B.

Not bad... 360 Lumens / 3.77W = 95 Lumens per Watt at nominal Vbatt

Cooler running than the XPG is a big bonus too. 

RedForest UK
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night_porter wrote:

Wow I did not know that Sherwood is a rain forest???

 

I live in Oxford and never have any problems with my drop-ins fogging up.

 

Maybe you should try changing them in doors with the central heating on? Laughing

 

Have you really never had any problems? It's common for me, with my normal assembly being done inside with central heating on.

 

It only normally happens with drop-ins driven over 2amps when in use outdoors for more than 2-3 minutes continuously. It has also happened with well-driven lights in stock form as well and is very common with bike lights as they have a lot of airflow onto their lense. Another thing to note is that the wider the lense is the greater chance that it will mist up.

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kramer5150 wrote:

sixty545 wrote:

RedForest UK wrote:

 

The LED itself is interesting, but in all honesty disappointing. Brightness is fine, it seems similar to my XP-Gs. But there is a lot of colour spread across the beam, way more than any XM-Ls I've seen, it gives the hotspot and spill a clearly yellowish corona with more blue central areas.

 

 

I got mine 5-mode today and I'm afraid I must agree with you. I did'nt notice at first but now I see the same bluish hotspot and I have a little yellow center in it.

I had great hopes that the new shape of the die (mountain-like) would get rid of the normal (for wide dies) yellow hotspot with bluish corona but they did it a little too much, I think so it's almost the opposite now.

The 5 mode is with the good old NANJG 47 (-A this time) with the small stars for programming on the back. It has the ATTiny13 (Hurrah) so I will modify with my own program.

The stock setup was:

Low-Medium-High-Strobe-SOS

20-120-360 lumens @ 56-330-1047 mA measured at 3.9V

16-106-360 lumens @ 42-280-1049 mA mesured at 3.6V

so the regulation seems fine (3x7135)

At 3.3V I measured 319 lumens on High.

So it seems to be a very efficient LED and it runs cooler than XP-G.

A pity with the mis-coloring.

I also got a "20"mm and a "16" mm star. They both gave 162 lumens at 350 mA so they are truly R5. The CCT was 5980K and they fit in bin 2B.

Not bad... 360 Lumens / 3.77W = 95 Lumens per Watt at nominal Vbatt

Cooler running than the XPG is a big bonus too. 

 

Mine is still in the mail on the way here Sad

 

How much will an XP-G R5 do with NANJG 47 @ 1Amp lumenswise?

Luckily, I have one dropin just for the comparo, R5 driven with 1A Smile

brted
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From the Cree datasheets, at 1 amp the XP-G R5 is 348-370 lumens while the R5 XT-E is 320-340. So the XT-E is acting a little more like an XP-G R4. However the XT-E output is rated at a higher temperature and if the XP-G were rated at the same temperature it would be a little lower too. So apples to apples, you could increase the XT-E output by 15% and get 368-391 lumens at 25 degrees C to compare with the XP-G. Now the XT-E is a bin brighter at 1 amp.

RedForest UK
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CheapThrills wrote:

How much will an XP-G R5 do with NANJG 47 @ 1Amp lumenswise?

Luckily, I have one dropin just for the comparo, R5 driven with 1A Smile

 

Around 260-300 OTF depending upon conditions and lense/bezel used according to my own measurements. The XT-E should be around 8-10% more efficient in total output.

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[/quote]

The stock setup was:

Low-Medium-High-Strobe-SOS

20-120-360 lumens @ 56-330-1047 mA measured at 3.9V

16-106-360 lumens @ 42-280-1049 mA mesured at 3.6V

At 3.3V I measured 319 lumens on High.

So it seems to be a very efficient LED and it runs cooler than XP-G.

[/quote]

So it drops 40 Lumens as the Vin depletes from 3.9-3.3V.

What is causing the drop in output?  thermal warming?, lower Vin?... both?  I would not expect it to drop that much if it is running cool.

brted
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kramer5150 wrote:

So it drops 40 Lumens as the Vin depletes from 3.9-3.3V.

What is causing the drop in output?  thermal warming?, lower Vin?... both?  I would not expect it to drop that much if it is running cool.

At Vin of 3.3V, you are getting below Vf at 1A for the LED so the current draw is probably down as well. The driver is taking some of the Vin for itself.

sixty545
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brted wrote:

kramer5150 wrote:

So it drops 40 Lumens as the Vin depletes from 3.9-3.3V.

What is causing the drop in output?  thermal warming?, lower Vin?... both?  I would not expect it to drop that much if it is running cool.

At Vin of 3.3V, you are getting below Vf at 1A for the LED so the current draw is probably down as well. The driver is taking some of the Vin for itself.

You are spot on, brted. The 7135 are out of regulation at Vb = 3.3V and the current drops.

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RedForest UK wrote:

CheapThrills wrote:

How much will an XP-G R5 do with NANJG 47 @ 1Amp lumenswise?

Luckily, I have one dropin just for the comparo, R5 driven with 1A Smile

 

Around 260-300 OTF depending upon conditions and lense/bezel used according to my own measurements. The XT-E should be around 8-10% more efficient in total output.

I think I will have to take this dropin to integrating sphere to see, what it gives OTF. 

sixty545
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CheapThrills wrote:

How much will an XP-G R5 do with NANJG 47 @ 1Amp lumenswise?

Luckily, I have one dropin just for the comparo, R5 driven with 1A Smile

 The output for XT-E is given at 85'C. It has to be multiplied with 1.14 before comparing it to XP-G.

So XT-E R5 gives 143x1.14 = 163 lm @350mA at 25'C.

    XP-G R5 gives 143 lm @350mA at 25'C.

I use a spreadsheet with formulas derived from Cree data and get:

                   XP-G    XT-E  at 1.0A

Led cold:       356    376 lumens

Led varm:      326    346 lumens *)

OTL varm:      261    277 lumens *)

junction temp: 68'C   65'C  *)

*) this is for a typical host (L2)

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Because these LED's are spec'd based on 85 degrees, would these be perfect for a low driven triple in a small host?

Or a multi emitter headlamp with next to no reflector creating a floody beam and stopping what could be an issue with the colour fringing beam?

brted
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I don't think the spec temperature means anything. It is just a setting at which they measure performance. Maybe some people complained that Cree was evaluating their LED's at room temperature when, realistically, the LED is going to get hot very quickly and it would be more realistic to measure the output when the LED is hot. The datasheets allow you to generate numbers at any temperature you want, it's just the default (100%) value is at 25 degrees for the XP-G while for the XT-E it is 100% at 85 degrees.

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So runtime should be amazing with this thing, huh?

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Rusty Joe wrote:

So runtime should be amazing with this thing, huh?

Exactly equal to any other LED driven at 1 Amp.  An XML, XPE, XRE or XPG driven to 1 Amp would have identical run-time**.

 

**Assuming a linear driver where Vf is irrelevant.  A switch-mode driver would vary the run-times a little according to differences in LED Vf.

 

PPtk

I am currently extremely busy with work. Please do not expect a response from me quickly. I will be dropping in as time permits, but the amount of time I can dedicate to responding to topics and PMs is very limited.

sixty545
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brted wrote:

 The datasheets allow you to generate numbers at any temperature you want, it's just the default (100%) value is at 25 degrees for the XP-G while for the XT-E it is 100% at 85 degrees.

Correct, and XT-E is 114% at Tj=25 degrees.

brted
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I wonder why they changed the temperature? Could it be that the carbide base of these chips doesn't transfer heat as well so they expect them to actually run hotter?

sixty545
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brted wrote:

I wonder why they changed the temperature? Could it be that the carbide base of these chips doesn't transfer heat as well so they expect them to actually run hotter?

On the contrary, XT-E has a thermal resistance to the base = 5 degr./W and the XP-G has 6 degr./W

I think they started binning XB-D and XT-E at 85'C as a new policy. You can easily make a verification test at that temperature. It is more difficult to set up a test at the north pole Wink

brted
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Got my XT-E drop-in from KaiDomain today. I love that it has 3 modes using the NANJG AK-47A driver. The drop-in has a smooth reflector, but the beam has a definite yellow center. The edge of the hotspot is a little green or yellow. Not sure if Cree will be able to work this out.

Cree XT-E Beam Shot

Here's the LED:

Cree XT-E LED

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That beamshot looks a lot like the LED I received.

I wonder if manufacturers like Eagletac suffer from the same problems with their D25 series.

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I tried some 3000K warm white XT-E in a homebrew 4x Mag mod that I'm not done with yet.  I tried a variety of reflector shapes, sizes and textures and even a few optics.  The one and only thing I tried that gave pleasant uniform color (instead of banana-berry swirl) were Ledil Boom Spot 20mm microfaceted reflectors.  I'd venture a guess that a Fraen 34mm microfaceted reflector might look good as well, but I don't have any spares or room for them in the light I'm building.

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Remember when the XMLs first came out we got horrible color change like that also. Hopefully quality control will come up after a while and we will get more even color dispersion

I am already visualizing the duct tape over your mouth.

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I would love to see a outdoor beamshot to see how the color of the beam translates to a multi colored environment.

The Giggle Loop

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but from what this thread has said, i think it would be better to apply the $8 one of these costs towards another xm-l drop-in.

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