Solarox GU10 / MR16 with Cree or Seoul **Pics added**

[Stromberg]

Does anybody have any experiences or comments of these Solarox bulbs:

http://www.led1.de/shop/index.php?cPath=168

They are advertised to give 3500lux / 50 cm (cool white) or 2500lux / 50 cm (warm white). Pity that there are no lux readings to longer distances.

 

[Stromberg]

Well, I bought one Solarox warm white with Cree. First impressions were positive but then I noticed that the heatsink of the bulb was very hot. It's not quite burning hot but feels unpleasantly warm. Does anybody know how well can Cree withstand heat in a long run? Or better yet, is there actual charts how Crees hold up in different temperatures?

Couple of pics

Beamshot(ISO 100, shutter speed 1/8s). In real world, tint is actually reddish:

Compared to Fenix L2T v2.0 with same setup. Tint is again different in real world(closer to daylight):

 

[Stromberg]

Hey c'mon guys(and gals), doesn't anybody have some useful info of how Crees hold up in high temperatures? Since I don't have an infrared temperature meter, I'll have to figure out the temperature of the heatsink using traditional means and post it later. I googled from somewhere that operating temperature is -40 to +85(Celsius) but that itself doesn't help much.

 

[Stromberg]

Nobody seems to be intrested of this topic so I'll quote at least something useful I found from other thread:

"Quoted from Cree Reliability Data Sheet "Based on this method, Cree projects XLamp LEDs to maintain an average of 70% lumen maintenance after 50,000 hours, provided the LED junction temperature is maintained at or below 80ºC."

So if temperature of the heatsink is <=80ºC near the emitter it should be OK.

 

[LED-FX]

Thanks for the beam shots.

Heatsink getting warm is good, it means some of the heat from the LED is getting conducted to it.

What it dosent mean is heatsink temp 80 C = Junction temperature, Tj on data sheets, being 80 C.Resistance of slug to star and then star to heatsink all mean Tj is going to be quite a bit higher

Sink looks big enough to run at lower temps so do wonder what the, famously not as efficient, warm white LED is getting run at and how...?

Cheers
Adam

 

[Stromberg]

Thanks for your reply. I'll have to measure temperature of the heatsink somehow and also find out how much Amps(or mAmps) it's drawing, although it means that I'll have to play with 230VAC.

 

[LED-FX]

Any contact thermo should give yousome indication, even a mercury one, if you can touch it guessing its lower than 80 C.

Really want the current the LEd is getting , put a meter in line with the LED after the driver or put a low value big wattage resistor in line and meter the volt drop accross that.

Interested to hear more thanks

Cheers
Adam

 

[65535]

If plausible I might recommend adding fa small fan to the fixture, LEDs are the only light source I can think of (for public use) that can burn themselves out without proper heat sinking.

 

[LED-FX]

Kills efficiency gains though, adding mechanical cooling.

There`s a few high power MR16 LED designs around that work reasonably succesfully.

Guess my concern with this one, from what Stromberg has already told us, is the heatsink is getting uncomfortably warm.

Single LED shouldn`t be generating enough heat to warm the whole heatsiink to uncomfortable temperatures.

Either the LED is being ovedriven or heatsink has to lose heat from the driver as well.

A. N. respected manufacturer`s rep was trying to persuade me that an undershelf lighting system using XRE`s on a small metal clad PCB was fine, " we find wood is a great conductor of heat" strangekly I didn`t place an order, now look at the rest of their range with considerably more caution as well.

Looking forward to hearing more about Stromberg`s investigations

Cheers
Adam

 

[Stromberg]

Small update: I managed to borrow Fluke 65 infrared thermometer and I'll make some temperature measurements and write test results soon.

 

[Stromberg]

It turned out that contactless infrared thermometer is less than optimal when measuring surface temperature of GU10 shaped bulb(or maybe it's because of the heatsink finish, which seems like chromium). I made two measurements in every five minutes: one directly facing the bulb(I turned the light off so possible IR generated by the led itself wouldn't mess the results) and another from the side of the heatsink.

After one hour the temperatures were 44,1°C (facing the bulb) and 33°C(side of the heatsink). This however didn't make any sense because at this point, the heatsink was uncomfortably warm to touch by hand. I decided to remove the glass optics and measured 57,2°C inside the bulb. I think that heatsink must have been closer to 60°C which would confirm my subjective observations.

What do you experts think? If heatsink is closer to 60°C what could be actual temperature of the led itself assuming thermal contact between PCB and heatsink is good?

Ps. I'll make current measurements bit later.

 

[Stromberg]

I finally managed to measure current draw and the results were weird: only 10mA when voltage is 224VAC, so total power consumption is 2,24w. Lamp is advertised to use 3w but that clearly is not the case. What do you think? Led itself can't be driven much more than 2watts because DC circuitry can't be 100% efficient. So what's heating the bulb so much? And if heatsink is about 60°C and thermal path is good, how hot can the junction temperature be?

 

[LED-FX]

60 C isn`t out of order for a high power LED sink to reach still puts Tj possibly past 100C which means light output diminishes


Possibly additional heat from driver as well, 2W real output may mean the LED is being driven at an average, to LED batch, constant voltage as it was a bit easier and cheaper, high precision sense resitors really arent cheap.

Cheers

Adam

 

[kirby]

How is the light output (brightness) compared to a typical 50W halogen?

 

[CM]

You need to be aware that IR thermometers will read temperatures with wide variation depending on the emissivity of the surface.

 

[Stromberg]

How is the light output (brightness) compared to a typical 50W halogen?

Sadly not comparable, 50W halogen puts out more light. And I can't recommend this Solarox-Cree bulb because (IMO) the heatsink is getting way too hot to be good for the led in long run.

I'm starting to lose my faith in these GU10 replacement bulbs. IMO leds are best used in distinct fixtures with optimized heatsinking, not crammed in some small heatsink, placed at ceiling where ambient temperature can be already several degrees higher than lower in the room.

 

[pygramube]

I have recently installed over 200 of the solarex MR16 lamps into a shop in north London. However we used the low voltage lamps as we had been advised they were more efficient. These were installed with specific LED drivers to provide the 12v power needed. I personally have a couple at my home, and have no problems with overheating. I think using the low voltage lamps may be the answer. Even though the lumin output is not comparable with the dicroic lamps they are still quite acceptable.