Least heat question

[videoman]

For the same amount of lumen output ( 1000 lumens), which would produce less heat : 3 XPG's at 333 lumens each or 6 XPG's at 166 lumens each ?. In other words underdriving 6 rather than regular driving 3 on the same heatsink. I am trying to keep heat as low as possible without using a fan.

 

[Justin Case]

Based on jtr1962's XP-G lumens chart, it looks like 3 XP-Gs at 333 lumens each corresponds to about 950mA drive current for each LED. For 6 XP-Gs at 166 lumens each, the drive current looks like it should be around 400mA. Next, looking at jtr's thermal chart, 950mA corresponds to about 2W of waste heat per LED, while 400mA gives about 0.75W. Thus, total waste heat for 3 XP-Gs at 333 lumens each is slightly more than 6W. Total waste heat for 6 XP-Gs at 166 lumens each is about 4.5W.

 

[qwertyydude]

I believe if you wanted even lower 3 mc-e leds would mean you have even lower power densities and efficiency would be even better and on top of that I believe the mc-e has better thermal properties too.

 

[videoman]

I thought that the XPG's are the most efficient leds out there at well over 100 lumen per watt. I already tried 2-MCE's and they really get hot at producing 1000 lumens combined. From what I gather, the waste power is given up as heat and the less is better.I will be getting a few XPG-R4 and will compare to the MCE's to see which run cooler, in different configurations, keeping the 1000 lumen desired as a constant. Thanks