^^^^^ EXACTLY what RedForestUK said.
Please keep doing what you're doing.
Please?
thats pretty much how i feel about it. i spent $30-40 on my cpu cooler, and i really didnt need it, wanted it there just incase. if i was going to mod this light, i would want a real heat sink in it. but since im not going to, what is there is sufficient.
would i rather of had them put a real copper or even aluminum heat sink in it? yes.
This thread is really interesting! And I thank Old Lumen for that!
And also Relic38 for those nice measurements!
I am still all for larger pills and better heatsinking that what is stock in that Nitecore light…
There doesn’t have to be anything wrong with a light for me to want a look inside. A well made light should allow for upgrades or modification. I begin to see the fascination of safecracking.
I agree, i like being able to upgrade with new technology as it becomes available
To Nitecore… Just wanted to tell you something…
This is NOT a hamburger!
This is
This is not a pizza!
This is
This is not an engine!
This is!
This is not a tractor!
This is!
And last but not least….
This is not a pill!
This is…. (one of many great examples found on this forum)
Thumbs up RaceR86! 
@ Old-Lumens
Did Nitecore threaten you or something? Please don’t take this down, it gives us all a really nice view of what’s inside, most would not want to open theirs up.
Thank you
@ RaceR86 +1 
Sometimes I want cheap, and sometimes I want something better. I sure don’t paying for something better and getting cheap.
A light’s ability to take regular use and last forever is better than cheap. A light’s ability to take “abuse” of running it on turbo would also be better than cheap.
If it can’t take the heat, it’s cheap. Now what was manufacturer suggested retail again?
I go away for 12 hours after my test results and somehow it shows that the EA4 has no issues? To me, it’s the opposite. I’m speaking as a flashlight hobbyist, not a casual user. Casual users do not care about 20% drop in output. I do.
O-L, your tear-down is still an eye-opener. It still shows a non-ideal thermal path. My data actually backs that up, at least a little.
Should everyone stop buying Nitecore because of it? Probably not.
Thermodynamics is a complicated and often misunderstood area of physics. My grasp of the concepts is enough to get me into trouble. I understand things like this through analogy. The one I use for heat transfer is vertical water flow through containers, via gravity. it’s hard to explain, but it works for me. Here goes nothing…
The water coming in is the amount of heat being generated. More water (literes/s) = more heat (Joules/s). One Joule/s is more commonly known as one Watt.
What you are pouring it into is the heat sink. For a heat sink, it’s an imaginary glass with a hole in the bottom. Heat comes in the top, exits the bottom. The size of the hole is controlled by heat transfer characteristics of the heat sink itself.
Theoretically perfect heat sink; a glass with no bottom (stops no water). This object cannot exist.
Theoretically perfect heat absorber; a glass with no hole (catches all water). Also cannot exist.
For practical heat sinks there is always a hole, the diameter of the glass is the thermal mass of the heat sink, and the height represents the melting point.
While water is flowing in, some escapes through the hole. As water builts up in the heat sink, the pressure increases, which will increase the flow through the hole. At some point the flow rate out the bottom will equal the flow rate coming in. However high the water rises up in the glass, that’s the temperature of the heat sink. If the water can reach the top of the glass, the heat sink will melt (it has not more heat capacity). When it’s empty, it’s at absolute zero (it contains no heat).
Now for the (slightly mind-bending) twist; the bottom of the glass is immersed in a very large body of water (maybe a barrel, pond, or ocean). This body of water represents the ambient air.
How deep the glass sits in the water represents how warm the ambient air is. If the glass happens to be immersed, the heat sink melts.
A heat sink with the emitter turned off will always have some heat in it from the ambient air. When the emitter is turned on, water begins to flow into the heat sink. This will begin to raise the water level in the heat sink until the rise in temperature creates enough pressure push the same amount of heat out of the heat sink (equilibrium). (I intentionally crossed over from analogy to real example).
For the EA8 heat sink, it has a very small thermal mass (small diameter glass) with a relatively small hole (poor contact with the outside world). A 10W emitter will very quickly heat up that heat sink. Once the thermal pressure is high enough, heat out=heat in and we have equilibrium. This happens within 30 seconds. After that we are watching the next layer of heat sink fill up (the body). Eventually that will fill up too (it didn’t happen in my graph, it takes longer than 10 minutes on turbo).
One more example and I’ll stop, I promise. What about the HD2010? Can we model that?
Here’s how I see it. I imagine four glasses (emitter base, star, pill, head) plus a pond (my office). The emitter glass is in the star glass, is in the pill glass, is in the head glass, is in the pond.
The emitter is a tiny glass with almost no bottom as it has very good thermal transfer characteristics. It’s directly soldered to the star.
The star glass is much larger than the emitter, but still relatively small and has decent thermal transfer characteristics being lapped (polished flat) and has silver thermal compound.
The pill glass is larger again and has OK transfer characteristics due to the thread surface area with thermal compound connecting it to the head.
The head is the largest glass and is connected to the ambient pond with a decent amount of surface area so the hole is a decent size.
(I cannot quantify the hole sizes, all I know is they are there, and I think of the relative size of each).
With the light off, all glasses are at the same temperature.
At turn-on, the emitter will very quickly fill up enough to push the heat along to the star. because the hole is big, it doesn’t require a lot of pressure.
The star begins to fill up as well, and it will reach equilibrium quickly as well.
The pill takes a bit longer before it fills up enough to match heat-out to heat-in.
The head is the last part and it will do the same thing. Once it equalizes, the temperature of each inner cup will stop rising as well.
So how did this help reduce the lumen loss due to heat buildup? At the emitter-star and star-pill stages, the hole is a little bigger than it would be for a traditional star, which means there is less temperature differential required to move the same amount of heat. Make a small difference at two or three levels and the cumulative effect is significant.
Of course, one bottle-neck anywhere along the path and you have a problem.
The EA8 (and most lights) have the biggest bottleneck right under the emitter; the dielectric layer of the pill. A direct bond star allows for a much better transfer from emitter to star.
The next biggest is the star-pill contact. A hollow or thin-topped pill will be another bottleneck.
The pill-head stage is usually OK since there is a lot of surface area contact.
I’ve probably confused everyone with my silly analogy, but that is what helps me understand it a little bit. I should note that it doesn’t cover all dynamics of heat transfer, but it’s good enough to cover what I need to understand.
Want to simulate it? Go get a garden hose, a bucket, some disposable cups, and start cutting holes. It can be easier to see it happening than read about it.
ummm…. not cheap :money_mouth_face:
i really dont think i would buy another nitecore.
I still don’t get it. You run the light beyond it’s designed parameters and then complain that it’s a problem. That’s like buying a car with a speed limiter, removing the speed limiter, and then complaining that the car can’t handle higher speeds. The light was designed to run on turbo for 3 minutes then step-down 33% (more than 20) and remain there indefinitely. There are a number of reasons to design it this way, less weight, less heat (less concern for “casual users”), less cost, more battery life. Perhaps their research has shown that 3 minutes of turbo pleases 99 of their customers. Who knows?
It’s perfectly fine for you to say it’s not a good light for hardcore flashlight enthusiasts who want to torture it or whatever, but to say that it has issues (without qualifying the statement) is just being dishonest. Your test was driving the light harder than normal without any mention of it. Please do another test to see how well it functions within its designed parameters, that’s what most people are going to benefit from.
Well stated…this is a AA light meant for a certain demographic.
I love this fact;
Quote: “Here is the plastic holder and the driver on the bottom side of it. On top is where the heat sink was mounted. It is all held together with two small pieces of clear tape.”
End Quote:
Sounds like real quality engineering to me, plastic & scotch tape H)
[quote=kronological]
If this keeps up much longer I may have to go to AA because of all the “cups” you guys are having me empty!
Uh, what? The problem occurs in the first 30 seconds. Thanks for not including that in the quote. Maybe you didn’t read that the three times I’ve posted it. I can’t blame you for skimming my lengthy posts.
I guess there’s no pleasing everyone. I gather some, what I believe to be, good data and still the issue cannot be seen. The EA4 is a $50 light that sags like a $5 hollow pill special.
Am I unhappy with my EA4? No. I still like it. I am disappointed in the thermal design, based on O-L’s teardown and my subsequent testing.
The way I see your test results is that they suggest that the relatively poor contact on the EA4 heatsink means that it needs to get to a higher level of heat saturation (fuller glass) before the heat differential with the body is enough to draw heat out of it as quickly as the emitter itself is putting more into it; leading to a higher operating temperature at the heatsink. This leads to greater heat sag originally, as it reaches these temperatures, but then it levels out to reasonable levels once that point of equilibrium (of heat going in and out, and therefore temperature) has been reached.
That operating temperature is still within safe levels, even in your tests which max the light out at full power; so we shouldn’t worry about damaging the emitter from running on high, and the contact can be classed as adequate. However, contact could have been better, and if it had been then the heatsink would need less of a differential between it and the body (relative water pressure differences lower with a bigger hole in the bottom) to reach a state of equilibrium. This would mean that the LED does end up operating at above-optimal temperatures, and therefore sub-optimal efficiency when run on the highest output.
OldLumens was onto something after all, it just wasn’t as bad as some people imagined.
I agree relic38, I still like my EA4 and EA8 but the build quality isn’t up to what it should be.They look great on the outside, not so good on the inside.I guess that explains all the loctite?Oh well, I’ll use them until or if they break but I don’t think I will by another anytime soon.Thanks for your tests, and thanks to Justin for getting this thing apart to reveal the uglyness. 
-Rick
I like the analogy Relic, i had no trouble following it, but since i already understood the concept it was a lot easier to follow
I’ve never taken thermodynamics, but to me it is easy to follow logically (just not the fancy calculus computations), i was at a talk about LEED building certification and the presenter was trying to explain thermal bridging in simple terms and not doing well, i wanted to take over with an easier to understand explanation, but that would not have been very polite