Thanks for the info. Your post in the thread you mentioned don’t have this 30s to 3minutes graph. So you are using battery to test right?
I have one EA4. Maybe I will do some test tonight with my freshly charged EneloopX.
No I didn’t say that. Here are links to the tests I did with the details, to include what types of batteries:
OK. One more post, just to announce a discovery that explains the discrepancy between mine and luvlites’ data.
Details in my Thermal Performance thread.
I’d agree except my confidence is a bit shaken.
First post here but thank you for cracking this light.
I don’t understand how the reading at turn on could not be relevant when judging output sag? True, it isn’t relevant when judging if heat transfer from the heatsink board to body is enough, that will show later, but it is still heat sag so the reading before that represents the maximum potential of the emitter at that current. That said it could probably only be improved by a better thermal junction at the emitter itself e.g. copper sinkpad with no dialectric layer.
could someone pls measure the temps at the star mcpcb? thanks
I thought this was about assessing the adequacy or not of how the light in use handles heat from the emitter. So I gave output sag in lux for five lights from (worst case) two seconds after turn on until three minutes after in two second intervals, and links to hours of throw sag data also in two second intervals.
About the first two seconds starting at turn on… I used to live in Missouri so I wonder what do we really KNOW about what happens during that period. I’m skeptical of anything I can’t measure.
Here’s what I was wondering. Maybe someone knows of data (not opinion) on this because I couldn’t find any. Exactly how much does the temp of the emitter rise in those two seconds and what would a graph of that look like? Exactly what would a graph of emitter output over those two seconds look like? Given all the components of each light and our lux meters, are we absolutely certain that max output occurs exactly at turn on and when we set a meter to capture max is that what it’s giving us and how accurate is it? Exactly how much of output sag is due to temp and how much is due to other factors? And even if we had equipment that could tell us all this to the millisecond, are the most efficient ways to dissipate heat in the first two seconds also best or even practical for extended use?
I guess some of that depends on exactly how high a temporal resolution you want (and are able to) look at, maybe it would take a fraction of a ms for an LED to reach full output, but the use of PWM can suggest just how quickly an LED can pulse on and off.
You might have to search through data at CREE for an idea of output sag at turn on, for the first half second or so I would expect any drop isn’t really anything to do with the design of the light itself but the transfer from the die out the back of the LED contact and from the LED to the PCB, with it taking another second or so before contact of the PCB to the light really makes much difference. So I can see where you’re coming from in saying that a drop in the first 2 seconds isn’t relevant for the heatsink design of the light, but it is still heat sag and could possibly have been improved through the use of a better PCB e.g. a copper sinkpad type one.
My test on EA4 shows that it doesn’t sag a lot, it sags to 97.25% at 3minutes if referenced to 30s output.
And if referenced to 0s output, it doesn’t sags a lot either, it sags to 95.73% at 3minutes.
From graph above, it shows the difference to reference to 0s and 30s, but for EA4, I think their difference is not huge.
Well this is my low cost meter measurement that I write down every 5s, so it is subject to measurement uncertainty that I might not capture the maximum output at 0s. I added M22 in the test to see how is her performance over 5 minutes.
I used freshly charged batteries for testing, not power supply. And this was ceiling bounce method.
I first thought ... oh oh.. I thought the EA8 was better that that.. I was happy with getting one.
But then I kept reading (the whole thread) and came to the conclusion that it depends on the information you have that you care about the heatsinking or not..
Because after all it does what it should do... and thats what its all about!
With or without the knowledge of the rather mediocre heat sinking....
Bottom line is that it gets the heat out to the body and that’s all that matters. It also means the way of thinking on massive heat sinks is not necessarily the right way, or the “scientific” way. The more I play around with heat sink, the more I see that as long as the heat sink is press fit into the head/body, to insure a tight fit, then the mass of the heat sink does not have to be much, like I am used to. I’ve been too many years working on Maglites, with their massive heat sinks, thinking that is what it must be, but it’s based on follow the leader, not facts. I still thing it should have been twice as thick, just for the sake of being sure there was enough heat transfer to the body, but that’s just me, not reality.
Thanks OL.. !!
I`ll be happy playing with my ea8 :)
How did you heat the light? A heat gun?
Did you have the light in a vice and use a strap wrench or some other method?
I used a butane torch and a vise. If I had a strap wrench I would of used it, but all I had was channel locks and a rag.
Harbor Freight…
to late now, its already modded, if he had a time machine i’m sure there would much better uses for it then buying a strap wrench prior to this mod
OL, thank you for opening one of your lights for us. I agree with you 100% that the heatsink design is poor and ugly.
Fortunately no signs of damage on the head... at least not after the polishing.
I was very surprised by how nice the threading is on inside between the head and body though.
Thanks, from looking at your pictures, one thing still isn’t clear to me. How is the aluminum star held in in place? Is it thermal epoxy or does the reflector hold it in place?
Only a bit of thermal paste. The reflector is supposed to hold it down.