Of course you’re not concerned about your readings being wrong. You’ve shown you’re not interested in facts or reality if they conflict with your opinions. So keep obsessing about those first two seconds which, in the scheme of things, are irrelevant. It’s even irrelevant by your own data but you don’t know how to interpret it.
Do you even have a copy of ANSI/NEMA FL1? If so please tell me where it covers initial sag because all the measurement standards I see start at 30 seconds. Or do you think there’s a conspiracy between ANSI and manufacturers to “cover up” initial sag?
Good luck figuring out “if some heat sink mods are required” when you don’t even understand your own data.
Luvlites, were your EA4 and TX25C2 not switched on for at least maybe 1 hour before the test? Look at the graph, looks like their sagging is not “natural” and might almost reach equilibrium of heat transfer in and out. I mean they look like they are already warm before your test, I suspect that is why they don’t sag as much comparing to others.
Both lights had been off for several hours and were room temperature. That graph does not include the first 30 seconds and is the normalized 30 second to two minute slice of a much longer test. If you want to discuss it in more detail, I’m happy to but it would be more appropriate to do so here where I posted those readings: Comparing Throw of the EagleTac TX25C2, Convoy M1, UltraFire UF-T50, & Zebralight SC600 Mk II
It is good to see measurement data from members, but let’s discuss it with objectives. Be cool.
My take is if the initial 0-30s max output is not used for advertisement by manufacturer, then when judging manufacturer’s flashlight sag over temperature, we should use 30s as reference point. It is because manufacturer is honest and follow ANSI standard. We have to be fair to honest manufacturer.
If a manufacturer use the 0-30s max output in their advertisement, then we don’t need to follow ANSI standard anymore since they try to cheat user with very good output number.
I know some modder just want to see thermal performance, and don’t care much about manufacturer being honest or not. But the test result might cause wrong interpretation about certain product. For example, if EA4 start out at 0s to be 1000 lumens, but Nitecore use 30s output which is 860 lumens for their spec, saying Nitecore EA4 sag a lot by percentage is not so fair. But if Nitecore use 1000 lumens as their advertised spec, then we can say EA4 sag a lot by percentage.
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.
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 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.
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.
