some measurements and observations on the Osram Oslon SSL 80deg. 4000K 96 CRI typ. led (nov26th: added a sk68 mod)

Interesting post .

Thanks for this .

Very interesting LED. 4000K and 96 CRI. Makes me drool all over the keyboard. ;) Too bad about the output though. Cant have it all..

Great post and testing!

Thanks djozz. Amazing work as well as interesting.

interesting post, thanks for testing and sharing!

great review and good to know they will reflow on xp boards alright. i do wonder if there is a significant loss in thermal footprint.

it looks like this same emitter is available bare and on Al star at led-tech.de

thanks for the appreciation :-) !

@Chloe: This led has a thermal resistance of 9.6 K/W, the Nichia 7 K/W, so the Nichia is supposed to shed heat a bit better, the graph seems to support that. I paid 2.32 euro for this led, but shipping for the order (7 leds) was 6.75 euro, so that is an extra euro/led.

@texaspyro: the maratac AAA copper had no glue, it was a straight swap, just reflowed the Nichia on the existing board. The mod was done a year ago, I would have used a copper board now. I have also modded the copper Maratac AA, that one was nasty: lots of silicone gooey (turned green from the copper, apparently not acid-free) inside the head, had to smoke the pill out with a blow torch and brute force, but the driver survived.

@islisis: hey thanks, that is a nice source for this led, rs-online only sells to companies (in my case: schools). So with that more easy source this led may after all find its way to more than one flashlight :-)

(I found that Osram has an improved version of this led, with a white backing instead of transparant, which is a bit more efficient. but that is not the reason for this post.)

I had one of these leds leftover and one cheap sk68 clone, so I made a sk68 clone with this led, should be nice with the 80 degrees angle. Very simple led-board swap, with the stock driver, the led on a copper Sinkpad, bit of Arctic silver around the edge to improve the heatsinking:

The results did not disappoint.

The current draw did disappoint a bit: 1.2A compared to 1.7A for a stock sk68-clone with XR-E led. I should have changed the driver after all, the led needs around 1.8A for best performance. I will put in a different driver eventually :-) .

The output zoomed out is 156 lumen and that is very nice: if you compare that to the test nubers above you see that 1.2A with a reflector and no lens gives 185 lumen, so even though this is an aspheric, it gets close to the output of a reflector light. This is one advantage of a narrow beam :-) .

Zoomed in there is still 113 lumen leftover, so that is 72% of the output of zoomed out, and that is really good (another advantage of the narrow beam); the stock XR-E version has 62%, and my dedomed XP-E2-mod does only 55%.

Considering only 1.2A current, the throw is ok: zoomed in 9.8 klux at 1 meter (zoomed out it is 0.83klux at 1 meter), compared to 14klux for my XR-E version. If the current would have been 1.7A as well, throw at 1 meter would go up to 12klux and that is close to the XR-E (but in 4000K and 96CRI ! :-) )

White wall beamshots, all taken at 4 meters with white balance on daylight and the flashlights zoomed in, the stock sk68-clone with XR-E is there for comparison, first overexposed to show the rings of the XR-E:

now exposed a bit less to have a look at the led-dies, this particular oslon led also has some blue, at the same spot as the other one, the die-size is somewhere in between the XP-G and the XP-E/XR-E:

and finally for a nice surprise, if you put a thicker o-ring where the lens part screws into the head (so that the lens is a tiny bit further from the led), the focus is a bit above the led-die in the cilindrical part of the led-dome, resulting in one of the holy grails of aspheric flashlights: a round hotspot, fairly even illuminated :-) . (Throw is not affected by this focus shift)

Concluding, this led does very nicely what I expected from it in an aspheric: because of its narrow beam less losses than other leds, with a relatively nice throw for the humble output of the led, with as a bonus a round and even hotspot. Osram makes the SSL80 in a newer version as well and also in much better efficiency than this one if you do not care about the high CRI. I am sure those will kill the old XR-E in both output and beam!

Also worth trying in an aspheric is the Osram Oslon Black (also available in all sorts of tints and CRI), with the same beam angle as the XR-E (90 degrees) but with more 'modern' output. I am planning to buy some of those when my funds allow it again :-( and perform some tests.

Nice! :)

Thanks for the reply RaceR :-)

perhaps a glass lens to reduce the chromatic abberation would do more justice to the hi-cri >_<

Not sure about that, but correct me if I am wrong :-) :

Chromatic abberation, at least what I can think of, causes hardly a problem in 'led die projection' (which is what aspheric flashlights do) because the object to be projected is a more or less evenly emitting led surface, so color shifts mostly cancel each other out, except at the edge. At least in this flashlight I can not see much gradually shifting of tint going from the center to the edge of the beam, zoomed in or zoomed out, it looks worse on the picture now that have another look at them. Actually the zoomed out beam at a short distance produces a more beautiful illumination than the led in a reflector because of the even illumination.

The glass aspherical lenses made fore flashlights that I have seen thusfar have worse optical properties than PMMA ones, to reduce chromatic abberation you need achromats (at least a doublet made of two different types of glass), this may be way too fancy for a flashlight, where you mostly do not not want a sharp image of the led die anyway.

very interesting post, thanks for sharing your playing experimentation. :bigsmile:

that’s interesting info, thanks djozz

a while back i bought a glass aspheric to replace a pmma one which i wasn’t happy with… yes it is the edge aberrations which are most noticeable to me, and only when zoomed in

the focal quality of the lens wasn’t good, so i gave up after that :confused: it did however lesson the aberration a little.

i guess glass optics are much more difficult to manufacture, but in principle i still am interested in sourcing some since they should exhibit less dispersion

Just random thoughts regarding output/efficiency based on your posts Djozz.

Your graphs are great by the way :-)

And they show that (If I´m reading this correctly)

Vf A Lumen

Nichia 3,6 1 205

4,1 2 340

Osram 3,2 1 160

3,5 2 250

And if you about watts and L/W you get

Vf A Lumen W L/W

Nichia 3,6 1 205 3,6 56,9

4,1 2 340 8,1 41,9

Osram 3,2 1 160 3,2 50,0

3,5 2 250 7,0 35,7

Which somehow makes the difference seem so much less to me.

Thank you for the insights to you testing. Interesting emitter for sure.

Do you know of any good PWM-based drivers for this LED?

The Vf is not much different from a XP-G(2), so this led is very suitable for using a 7135 based lineair driver in a 1xli-ion set-up. I'd say 1.5-2A is a good current to get the most out of the led, so perhaps a Nanjg 101-ak (1400mA) will do the job wel, or the 6x7135 driver from Fasttech.

Thanks for your interpretations, and for comparing the efficiency of these leds, it is only fair of course to take into account the voltage difference as well. To complete the comparison, you should also compensate for that during the Nichia 219 measurements the reflector had a AR-coated lens on top, and the SSL80 measurements were done without lens (why do americans call a flat piece of glass a lens by the way???), that should add 1 or 2% to the Nichia values.

That is true. Should have remembered that :-)

Thank you! Judging by the heat from a 3x7135 that might be too much for a smaller Convoy but I still want to have a high-CRI outdoors torch, so an excuse to make a C8 with one. :bigsmile:

Could this led do well in an 18650 host ?.

I’m looking for best hcri, and runtime - more than lumens.
Also is the Vf an issue compared to say a Nichia 219b v1?.
I’m looking for at least 2 hours+ runtime on high and maybe no more than 200 lumens.
It’s between this and a Nichia!.
Thanks.