[TEST] Temperature dissipation (aixiz versus o-like)

The tests were made with 140 diodes, both running at 4.2v 600mA.


case temperature when off
(both): 28ºc (ambient)

case temperature when on (aixiz) after 15 seconds: 40ºc and going up
case temperature when on (o-like) after 90 seconds: 40ºc apparently stopped heating

time to reach ambient case temperature after tests
aixiz: 45 sec to 31ºc, 70 sec to 28ºc
o-like: 50 sec to 31ºc, 90 sec to 28ºc

heat dissipation
aixiz: 2 to 3 seconds to transfer heat from one side to the other side of the module (tested with hand touch)
o-like: instant

Mass Quantity (someone could contribute with this info, if possible)
Aixiz material: electroplated brass (nickel/zinc finish). Thanks LazyBeam!
(Unknown mass)

O-like material: Anodized aluminium.
(Unknown mass, but at least 2x than aixiz)

The aixiz module cannot handle more than, lets say, 500mW of heat generated. The o-like was handling 2W pretty well and, I think that in a cold winter it could handle these 2W continuous.

I'm sorry, but I don't have a LPM to test the actual power input - light output to calculate the heat but, it is really around 2W (2,52W in, ~500mW out ~2W heat).


edit: inserted graphics for o-like and aixiz. I drawed it as I feeled they perform, not real temperatures mid-graphic. Only the first and the last numbers are real, the others are how the module perform (aixiz = logarithmic curve, o-like = near linear curve). The numbers are how much temp. the modules gained, above 28ºc (for example, aixiz is 12 at 15 seconds, 28ºc + 12ºc = 40ºc). All temperature is expressed at Degree Celsius escale (metric).


[These tests are part of my diode temperature controller project, that I'll share with LPF when it is ready (if it goes ready )]

edit: sorry for the "-2" temp. at the o-like graphic.

Thank you for sharing those results with us,
I personally preferred the O-like as it did perform better, but now its nice to see some data to actually back that claim up.

Yeah, someone said it is hard to add extra heatsinking because of the fins, but that proofs that the heat dissipation goes thru the whole o-like body so, heatsinking 50% of the module will have a good eficiency if compared to aixiz. I'll make a draw explaining that soon

edit:
here is a drawing by me (damn tinypic, lowered color quality. it is attached if further analyzing is needed, it is zipped because it is a BMP file)


labels, aixiz picture
the red arrow represent where the heat goes in the module. The red lines are the best location for dissipative material to be added. Blue lines are the good locations.

labels, o-like
the purple lines are the threads for attaching the head to the back barrel. the greenish part is the diode holder lock (made of aluminium). the red arrows are good heat transfer. as no metal is perfect, the blue arrows are 'slower' transfer, hence bad for a heatsink in that place. O-like has double the mass of a aixiz, and can transfer heat very better than it. Fake colors

By the way, I don't know if you tested it this way,
but could you try testing out both Aixiz and O-like with their housing case on?
that means the cylinder that comes with the modules themselves.

My case I found that this is where my heat was dissipating the most, through the solid AL body of it rather then the head with the fins.

Or this is how you tested it already?
This is how at least Ive been doing it, as I feared the lack of surface area if I used just the fins alone. (the head itself, without the case)

What exactly are you testing here?
A lab module?

The backbarrel? yes I passed thermal grease and tested 'em.
That what I mean in "HEAT DISSIPATION". read again :beer:

@RA_Pierce I'm testing the bare modules only, without extra heatsink.

Those 18mm O-like modules are great. I also like how I don't have to press the diode in, so I can actually swap out diodes for tests and such. If you're buying one of the O-like lenses, you can essentially get one of those 18mm modules for $2.50 more.

They behave this way because of thier radiant capacity. Notice how the aixiz module stays relatively cool and then temperature skyrockets. This is because it is behaving like a thermal-mass heatsink and once the thermal mass is saturated there is no efficient rejection of heat so the overall temperature must rise. However, as the olike rises in temperature (easier because of the low density and quick thermal conductivity) the temperature tapers off because the heatsink is able to reject (emit) heat to the air faster than it is input.

The Aixiz module is electroplated brass (nickel/zinc finish). The O-like module is anodized Aluminum with integral fins/grooves. Everything is working in the olike's advantage. Aluminum is a pretty good conductor of heat while brass is less than half as good as aluminum. So even a "scaled up" version of the aixiz would not soak heat very well. Anodized aluminum has a thermal emissivity (ability to radiate heat) of ~0.8 while Nickel/Zinc finishes will emit @ 0.05 ... AND ... the olike has more surface area (due to diameter & fins) to use that emissivity to radiate heat.

I'm pretty sure that even if the 12mm aixiz were pure copper that the Olike would've beat it in a long run test because it can reject more heat in a steady state fashion. The best designs will have a copper or silver bulk heatsink either finned with a high emissive coating or jacketed with a finned anodized aluminum shroud. You can see this on high-end PC coolers... copper heat plates with copper heatpipes that wrap up to coated copper or anodized aluminum fins.

It's all about the steady state heat rejection capacity

BB is right, when buying lenses from o-like you can get a module for 2.50 bucks, thats very good. And the diode locking feature is pretty impressive too..

LazyBeam:
Thanks a lot for explaining and giving more consistent info. +1

Leo, did you use thermal grease when you installed the diode into the O-like?
I did with mine, after having read that suggestion somewhere.
Since it is not press fit, it is a relatively "loose" fit.

I think the o-like module is THE way to go for high current diodes, like the blue nichia or, say, 12x BluRay.

anselm: sure, thermal grease in both testings were used for better contact, and a strong 'loose' fit.

yeah, the o-like IS the way to use high current on diodes, or on whatever diode that heats a lot. even a LOC without extraheatsink will perform very well using this module.

edit: actually, when I first tested the o-like to compare it to the aixiz, I got very afraid that the diode was damaged, or was with insuficient thermal grease, because it wasn't heating, I thought that the diode was retaining heat to himself and leaving the module cool. I was wrong, as all here can see

Please label your axes on your graphs. Thanks.

Yeah I love the o-like module. I use one to test every diode before I put it into it's final home. It is great because of the screw on diode lock. Also unlike the axis, the backbarrel is thick metal and add a good bit of heatsink mass.

The only problem I have with it is how far you have to screw in the lens to focus it, especially if you try to use an axis lens you have to screw it actualy inside with none sticking out ( they are like half the length of the original lens)

sorry limecat, didn't understand what you mean.

benmwv: using o-like glass lenses solve that problem, but they still go inside the module.

@leo:
he wants to know what the numbers mean.
@limecat
X-axis is time elapsed in seconds.
Y-axis is Δtemperature in degrees celsius