Well... What you think, is the heat problem in these MR16 LED-versions, and i mean about 3w "bulbs". Normally those are installed in places where the air is not going to change. So...are those getting too hot? Is the heatsink big enough anyway in these products?
LED MR16 and the heat?
- Thread starter Juctuc
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I think that heatsinking in MR16's are comparable to GU10 and E27 based replacement bulbs that I have tested resently. When using >= 3 watt emitters, heatsinking in those bulbs just doesn't seem to work very well. Even if the heatsink is massive, like in this bulb:
..if heatsink is only place where heat can go - and there is not even moving air that helps to draw heat - it will get very hot. Last night I tested that 10 watt bulb and after about two hours it was so hot that I couldn't touch it longer than one *second.
My opinion is that leds shouldn't be jammed in small replacement bulbs. Instead light manufacturers should be designing new light fixtures with optimized heatsinking.
*Ps. Today I was trying to find good accurate thermometer that would be rated over 100°C but the hunt was not succesfull..
..if heatsink is only place where heat can go - and there is not even moving air that helps to draw heat - it will get very hot. Last night I tested that 10 watt bulb and after about two hours it was so hot that I couldn't touch it longer than one *second.
My opinion is that leds shouldn't be jammed in small replacement bulbs. Instead light manufacturers should be designing new light fixtures with optimized heatsinking.
*Ps. Today I was trying to find good accurate thermometer that would be rated over 100°C but the hunt was not succesfull..
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R33E8
Newly Enlightened
The only LED MR16's I have experience with are Lamina's 8 Watt MR16's... Their heatsinks get to about 80C... Skin burns at 55-60C... Still much cooler than filament bulbs..
If heatsink is that hot, led chips must be screaming for mercy inside the bulb.. :shakehead
LukeA
Flashlight Enthusiast
Most decent or better multimeters come with a thermocouple probe.
R33E8
Newly Enlightened
Well with the emitter's having a thermal resistance of 3 - 3.5C/W, they nicely below the limit of 150C... I checked the website to make sure and it said the bulb had a heat sink temperature of 68C at an ambient temperature of 25C..
I'd like to have accurate thermometer instead since I already have two multimeters.
Yes, that may be in the limits, but do you have some manufacturer data of how higher chip temperatures affect lifetime and brightness of the led?
My point being that cooler you run the led, longer its lifetime and higher its output. And it seems that those MR16/GU10/EXX replacement bulbs just don't have what it takes to run leds as cool as possible.
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R33E8
Newly Enlightened
Like this?
http://www.laminalighting.com/userf...01 Life Lumen Maintenance and Reliability.pdf
I must say, there is quite a bit of engineering in that heat sink.. Their ratings are also all true and tested while the fixture is running at operational temperature, not initial.. I personally do not trust any other LED lights as of right now.. But I do plan on gathering some up and seeing how well they work some time in the future..
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James Jackson
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I am using 3 5-Watt LED 'lamps'. These are single LED Hi-Power LEDs (as opposed to the multiple lower-power LED variety).
Each one puts out around 150 - 160 Lumens of light. I have been using them for about 4 to 5 hours each night - for over a year now.
They get hot - the package that they came in says 65-degrees Celcius.
I feel that heat is just a part of the higher powered LEDs.
(Interesting side-note - the side of the box that they came in rates them at only 25,000 hours.)
The heatsink on them is massive... and gets hot.
Regards,
James Jackson
Each one puts out around 150 - 160 Lumens of light. I have been using them for about 4 to 5 hours each night - for over a year now.
They get hot - the package that they came in says 65-degrees Celcius.
I feel that heat is just a part of the higher powered LEDs.
(Interesting side-note - the side of the box that they came in rates them at only 25,000 hours.)
The heatsink on them is massive... and gets hot.
Regards,
James Jackson
Well, I'd be more interested to see graph that states lumen maintenance in different led die temperatures than overall lumen maintenance during led lifetime. That would be really interesting to see since Lamina advertises exceptional thermal characteristics. Makes me wonder why Lamina is not as popular in replacement bulbs as Crees, Luxeons and SSC's? Price? Availability?:thinking:
But even if Lamina leds indeed are more resistant to high temperatures, not all are. For example some SSC's are reported to have very poor lifetime and/or visible tint shifts in high temperatures.
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Two possible explanations that come to my mind:
1. They are more realistic about the lifetime expectancy than most of the manufacturers (even actual led die manufacturers..)
2. They know that high temperature shortens led lifetime
..or maybe both?
LED-FX
Enlightened
IR non contact thermos, usually with inbuilt laser pointer, are getting very common nowadays.
Adam
I specifically want quality contact thermometer since IR meters are not so good in all situations. You can read more from my experiences here:
http://www.candlepowerforums.com/vb/showpost.php?p=2241691&postcount=11
http://www.candlepowerforums.com/vb/showpost.php?p=2241691&postcount=11
brokemypalm
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It's the preference of the manufacturer what they want to do. If they want to overdrive the bulb more than it's "rated" power, then it will definitely be brighter than other bulbs, but at the expense of the 50,000 hours lifetime. So potentially the manufacturer could push lower quality bulbs harder to give the same amount of light as a better, more efficient bulb. In the end, it just depends on what you want. Is price more important, or is it quality? There's no right answer either way.
So my point was just that it depends on the inner circuits of the led bulb (set by the manufacturer) that determines how much "heat" is produced, rather than the technology involved.
Not necessarily as you can read from my Solarox experiences. It uses Cree XR-E which was actually underdriven and additional electronics didn't produce much heat. In fact, the electronics was in plastic case behind the led without any significant thermal path to the heatsink. One possibility (in addition that maybe GU10 sized and/or shaped bulb just doesn't work well as a heatsink..) is that the shiny chromium surface material reduces heatsink -> air heat transfer.
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We found a 3W LED we're testing that is WAY brighter than most that we've seen - that use 3 x 1W Cree LEDs. They use about 15 high power LEDs - in a unique pattern. It gets quite hot, but now skin burning like the Lamina bulb. It's Korean - so uses a no-name LED chip.
