I am not pointing anyone. Sufficient or not is unknown yet and subjectivce. What if current heatsink make EA4 LED decaying within 3 years time, with better heatsink, it won’t decay much in 10 years, we don’t know. Or better heatsink can make EA4 on Turbo for 20 minutes?
Well, here we go. Some rather surprising results along with some not so surprising results. I have not quite finished interpreting the data, but it's interesting to say the least. I would like to have data on emitter temperature, but that's not going to happen. Anyway, here it is.
EA4W XM-L U2 NW and HD2010 XM-L2 T6 1C on a copper SinkPad
| Time | EA4W Temperature (Deg C) | EA4W Output (Lumens) | EA4W Current (A) | HD2010 Temperature (Deg C) |
HD2010 Output (Lumens) | HD2010 Current (A) |
| 0:00 | 24.0 | 772 | 2.21 | 23.8 | 1146 | 4.03 |
| 0:30 | 27.0 | 685 | 2.19 | 25.8 | 1104 | 4.03 |
| 1:00 | 28.8 | 677 | 2.19 | 27.4 | 1099 | 4.03 |
| 1:30 | 30.6 | 671 | 2.19 | 29.2 | 1092 | 4.03 |
| 2:00 | 32.2 | 667 | 2.19 | 30.8 | 1087 | 4.03 |
| 2:30 | 33.6 | 664 | 2.18 | 31.6 | 1082 | 4.03 |
| 3:00 | 36.0 | 659 | 2.18 | 32.8 | 1080 | 4.03 |
| 3:30 | 37.2 | 657 | 2.18 | 34.0 | 1076 | 4.03 |
| 4:00 | 38.0 | 652 | 2.18 | 35.4 | 1074 | 4.03 |
| 4:30 | 39.2 | 649 | 2.18 | 36.4 | 1071 | 4.03 |
| 5:00 | 40.6 | 644 | 2.18 | 37.2 | 1069 | 4.03 |
| 5:30 | 41.8 | 642 | 2.18 | 38.4 | 1066 | 4.03 |
| 6:00 | 42.6 | 639 | 2.18 | 39.2 | 1063 | 4.03 |
| 6:30 | 43.4 | 635 | 2.18 | 40.0 | 1060 | 4.03 |
| 7:00 | 45.0 | 633 | 2.18 | 40.6 | 1057 | 4.03 |
| 7:30 | 45.6 | 630 | 2.18 | 41.4 | 1055 | 4.03 |
| 8:00 | 46.4 | 626 | 2.18 | 42.6 | 1052 | 4.03 |
| 8:30 | 47.6 | 624 | 2.18 | 43.0 | 1050 | 4.03 |
| 9:00 | 48.6 | 622 | 2.18 | 43.6 | 1048 | 4.03 |
| 9:30 | 49.2 | 621 | 2.18 | 44.2 | 1046 | 4.03 |
| 10:00 | 49.8 | 618 | 2.18 | 44.8 | 1043 | 4.03 |
And because we all love pictures, here's a graph.
The major initial drop occurs in about 7-10 seconds on both lights. The EA4W continues a less dramatic drop for about 15 seconds. After about 30 seconds, both lights seem to heat up at about the same rate, the EA4W warming up quicker. A quick glance and you might conclude that thermal transfer in these lights is similar because after the initial drop they warm up at about the same rate. You might even conclude that the EA4W has better contact because it warmed up quicker.
This is incorrect. The much larger drop exhibited by the EA4W indicates that the emitter got hot quickly. Once the thermal differential between emitter and heatsink rose enough to move the ~10W of heat, things stabilize. I attribute a good portion of this to the dielectric layer on the star, the rest to the lack of good heatsink coupling to the outside world.
On the HD2010, the direct copper bond requires a lower temperature differential to move the ~14W of heat away from the emitter. After things stabilized, the rate of increase is the same.
I intentionally chose more power for the HD2010 because it has a larger heatsink and I wanted the temperature rise to be about the same in both lights. I almost got it right on. I underestimated the power output of the EA4W and overestimated its heat capacity.
Now let's look at some percentages.
Lumen drop from 0 to 30s: EA4W - 11.3%, HD2010 - 3.58%
Lumen drop from 30s to 10m: EA4W - 9.8%, HD2010 - 5.5%
Total Lumen drop: EA4W - 20.0%, HD2010 - 8.9%
First, anyone concerned about burning up their EA4 (and probably the EA8) emitter has nothing to worry about. The emitter is probably getting hot, but no where near 150C. In my 10 minute test, I'd guess it got to 80C or 90C. That puts the body-to-emitter differential around 40C. In order to get to 150C, the body would have to get to 110C. There's no way 10w of heat could get this much material (surface area) up to 110C in open air.
Working in the other direction, with a body temperature of 50C, the body-to-emitter differential would have had to be 100C in order for a 10 minute turbo run to approach the emitter max temperature. A 100C differential would be difficult to obtain, without trying to do so.
I think the surface area and contact points of that EA4 heatsink is adequate to move 10W of heat with 40C of thermal 'pressure'.
Whoever has the capability, I'd like to see a similar test run on the EA8. I really cannot imagine how NiteCore could have designed it to overcome thermal dropout. Especially after seeing inside and these results from its similarly designed EA4 cousin.
That is very thorough test and result analysis. Since EA8 is bigger in size, it has more thermal mass. But difficult to imagine it doesn’t have thermal dropout.
I’ve just found that Nitecore mention Unibody for EA4 on their website. But many flashlight with unibody don’t advertise they are unibody either. So this unibody term is subjective to interpretation?
Thanks relic, i can shut up now
Thanks for the test. Sorry for my ignorance, but how did you avoid the EA4’s step-down?
The EA8 has been tested (albeit not temperature or voltage); by selfbuilt (graph on the first page), luvlites (earlier on this page), and subwoofer (on that other forum), perhaps others. They all show no apparent (significant) thermal droop. Running the smaller EA4 beyond its designed step-down isn’t indicative of the EA8’s performance.
I mean: What are you thinking might show up by measuring temperature and voltage along with the already measured lumens?
I don’t get it.
It drops down from turbo after three minutes. As soon as it dropped I immediately half-pressed to return to Turbo.
The selfbuilt graph is on high. the light probably has reached thermal equilibrium, meaning heat input equals heat output. The temperature of the light was no longer rising after three minutes. That is why I asked for a test like mine that measures temperature.
You mention the thermal mass of EA4 and how it does not compare to an EA8. What about the HD2010 results on the same graph? I bet it has more thermal mass than the EA8, and better thermal coupling with the copper pad. Do you believe the EA8 can handle heat better than that setup? I do not.
The graphs of both lights clearly show lumens as a function of temperature. If the light temperature goes up, emitter temperature goes up, and lumens go down. It is unavoidable.
I’m trying to wrap my head around this. Selfbuilt’s EA8 graph shows the light on turbo, there is a drop in lumens in the first minutes due to inevitable thermal droop before equilibrium. Then the light steps down a few percent. Then the graph is flat for the next ~90 minutes. The light seems to be operating within its designed parameters. This is what I’m going from. I’m not trying to be difficult, I’m just having a hard time figuring out what insight a temperature reading will provide.
I don’t really care about the HD2010. Should I?
Lumens as a function of temperature. Right. But you’re operating the EA4 beyond its designed parameters. Inside the EA8 (or EA4), thermal equilibrium could be reached as far as the LED is concerned while the body temperature is still rising. Why don’t you run another test and let the step-down occur. Still… as far as lumens go, those graphs are flat. Maybe it’s the scotch or the sleepiness, but flat lumens = thermal equilibrium = things are rockin’. I’m all thinked out for tonight.
nope it is very very unlikely that NC is using some complex circuit to compensate for the lumen drop arising from high temps
the reason the graphs are quite flat is because you’re looking at the WRONG parts of the graph. the nitecore disc is a small thermal mass so it ramps up in temps very quickly within a few seconds (it has high thermal resistance to the body of the flashlight so it will do this). this is the critical period that experiences lumen drop
One also needs to keep in mind, that selfbuilt’s light was a pre-production sample supplied directly by Nitecore for the purpose of a public review; therefore you really can’t trust the results because we don’t know if they cherry picked that light for the review or even IF the production light they are shipping has the same exact internal parts/design. You’ll also notice if you’ve read his reviews over the years, he carefully words them to not upset the manufactures; in many reviews if you read between the lines you’ll get the real picture.
Just like the holster on the P25 they had reviewed did NOT get shipped out in their retail production units.
One must always take these manufacture’s supplied test sample reviews with a grain of salt.
A much better test would be to purchase one from a Retailer and the retailer not be able to associate the buyers name with that of a well known reviewer.
For people mentioning a positive feedback loop and thermal runaway from Nitecore trying to compensate for lumen sag by increasing current, it’s true in a sense, but increasing current would still increase output more than the increased lumen sag would detract from it so it would still be technically possible to compensate in output terms by doing so, which is why I didn’t bring it up before. Anyway, it doesn’t really matter as while possible it is still completely implausible that nitecore would do that anyway.
Thanks for doing that more complete test relic, interesting results.
I thought self builts runtime tests used a fan. If so that explains why his runtime tests often are flat.
This heatsink doesn’t look good, but then again look at the new Cree 9.5W LED (60W replacement) bulbs from home depot. They don’t even have much of a heatsink at all. I was very shocked how they are capable of dealing with 9.5W’s and Cree stands behind them with a 10 year warranty…
Yeah the fan explains why it keeps completely flat, but cooling to the body can only work effectively if there is a decent thermal path to the body in the first place, so it was still good evidence with regards to heat sag (or lack of it) with regards to that issue.
I know what you mean about LED bulbs, they are generally press-fit into the heatsink with little contact area and run at high output and temperatures for extended periods of time way beyond what any of our torches can expect to be put through.
Honestly, Thank you for testing it.
It took someone with some knowledge, skills and some reasoning ability, to show that what I did to begin with was wrong, because I have no knowledge, no skills, or scientific reasoning ability. I just go with knee-jerk reactions and mistaken assumptions confirmed by misleading information, based with no scientific or logical testing to prove it. I do it all the time. I've done it all my life. It's a big weakness of mine, but I have no desire to change.
I edited the OP, to warn people that this thread is useless to read, because my initial assumptions are totally unfounded and just more hot air, as I like to do all the time.
I sincerely apologize, but I won't ever change, so just leave it at that.
Buy Nitecores, there's nothing wrong with them. Actually there's probably no lights out there that will hit a 130c or higher, so what does any of it matter.... See, right back to the blanket statements with no confirmation... That's me.
See ya.
I didn’t use a fan and my EA4’s output was flat for over 45 minutes both times I tested it (see graph I posted above). Considering that data was recorded every two seconds, output was very stable.
FWIW here’s how my EA4’s output declined just before stepdown. I can do it again recording every second but every two seconds still captures the essence of the decline over the first three minutes, starting with a “cold” light (room temp).
As a side note on heat sag, I didn’t use a fan with any of these four 18650 lights either and they all got HOT. Recorded light output every two seconds here too, but not temperature, and am wondering about the heat sag, especially with the Convoy M1.
I tested the Cree bulb. That heatsink gets over 100 degees C! And the light’s lumen output drops over 20%. The caps in the driver are rated at 105C. It would be interesting to get a thermocouple on them… particularly with the bulb mounted base-up…
I think most are interested with EA4 running on Turbo all the time. That is when heatsink performance is very important.
O-L, when it comes to knowledge about flashlight mods, there’s you and there’s us mere mortals, so don’t you think you’re being a little too harsh on yourself,even for you :)? We all have our strengths and weaknesses and together we collectively fill in the gaps of our individual knowledge.
Yeah but that’s abusing the light by running it beyond what it’s designed to handle because it steps down after three minutes for a reason. That doesn’t make it a bad light because the EagleTac TX25C2 and the Zebralight SC600 Mk II also step down for example. With that said, all this discussion’s motivated me to seriously think about abusing my EA4.
O-L, I can’t tell if you’re being serious or not, but if so you are being way too hard on yourself. Your effort in taking it apart and looking inside is greatly appreciated and you highlighted some genuine concerns about the heatsink design and internal quality, a lot of which is still valid.
Yeah, you probably over-stepped the mark a little in assuming the heatsink design was worse than it is, but from what it looked like I, and I’m sure most others on here too, would’ve made similar assumptions.
The thread is anything but useless, and you shouldn’t underestimate your knowledge and contribution to this forum.
To me, good heatsinking is also a matter of prestige. A little bit like with computers, I don't care if my CPU runs fine with the boxed cooler doing 60 °C on full throttle, I prefer to spend a few extra bucks, slap a huge chunk of copper and aluminum on the processor and enjoy the fact that it maxes out at 45 °C on full load.
While the heatsinking of this light may be absolutely adequate, it is certainly not ideal and therefore may not be desirable for enthusiast users - even if it's just because of psychological reasons.