Convoy S3 - highest continous current?

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vex_zg
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Convoy S3 - highest continous current?

any suggestions what is the highest continous current that this can be driven at using xml2, without damage to the emitter or battery?

in let’s say 25*C degrees ambient temperature, no airflow, not being heatsinked by your hand.

comfychair
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The light will tolerate more than what you can get from a single cell into a single LED. Assuming, of course, the LED is on copper. The light itself is not going to be the limiting factor.

wight
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comfychair is right about the LED. “Lumen maintenance” may be less than ideal, but you probably won’t kill it. I don’t think that the battery would vent even from repeated DD with an XM-L2. The battery will have a lower total number of cycles due to the heat.

(You shouldn’t base your safety on my assumptions though.)

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comfychair
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I 'test' them by dropping in a freshly charged 25R, switching it on, tailstanding it on the table until the low voltage protection in the driver shuts itself off. Never had one not survive that. You would need asbestos gloves to hold it while doing that, but it doesn't damage anything in the light.

wight
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Nice!

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vex_zg
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comfychair wrote:

I ‘test’ them by dropping in a freshly charged 25R, switching it on, tailstanding it on the table until the low voltage protection in the driver shuts itself off. Never had one not survive that. You would need asbestos gloves to hold it while doing that, but it doesn’t damage anything in the light.

i don’t care much about the host, not much to be damaged there, perhaps the o-rings or the reflector, but it’s pennies. I am somewhat concerned by permanently damaging the emitter thus reducing it’s output.

I am though more concerned about the battery doing the thermal runaway.

so perhaps I need to do a test to verify if something will get damaged.

comfychair
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Test it yourself if you like, but you aren't going to be running at higher currents than I do/did. These are direct drive lights with hot INR cells. The single LED lights run at a little over 5A, the triples are closer to 10A.

vex_zg
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comfychair wrote:

Test it yourself if you like, but you aren’t going to be running at higher currents than I do/did. These are direct drive lights with hot INR cells. The single LED lights run at a little over 5A, the triples are closer to 10A.

I’m running it max with 2.8A measured at the tail cap (8*7135), the reflector section of the light gets hot very fast. The star is aluminum, using very high quality thermal paste (gelid gc extreme).

What hosts did you use for the triple emitter lights when testing? I guess you know, but Convoy s3 is a pretty small light, just a tad bigger than the 18650. It’s got direct thermal path shelf for the emitter.

comfychair
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I have built several S3s. Single XML2 & XPG2, and a few triple XPG2s. You cannot make enough heat with only one cell, and the LED or LEDs on copper, to damage anything inside the light.

dw911
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vex_zg wrote:

I am though more concerned about the battery doing the thermal runaway.

so perhaps I need to do a test to verify if something will get damaged.

A quality cell should allow for non direct heating(say placing it in the oven, not attacking it with a blow torch) from ambience temperature to 130c for 60 minutes with no fire or explosions Smile

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 I wonder about hung lights vs tailstanding lights .

The heat hitting the battery harder since it's above the emitter  . 

                 υμεις εστε το φως του κοσμου ου δυναται πολις κρυβηναι επανω ορους κειμενη

                            Dc-fix diffuser film  >…  http://budgetlightforum.com/node/42208

vex_zg
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Boaz wrote:

 I wonder about hung lights vs tailstanding lights .

The heat hitting the battery harder since it’s above the emitter  . 

that happens because of hot air streaming upwards, don’t think it’s significant in these cases.

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keep in mind the li ion battery could get hot enough to make it dangerous, while the light is on and internal damage that does not become apparent till it explodes in the future

The Journal of Alternative Facts

"It is critical that there is a credible academic source for the growing and important discipline of Alternative Facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists."

 

vex_zg
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comfychair wrote:

I have built several S3s. Single XML2 & XPG2, and a few triple XPG2s. You cannot make enough heat with only one cell, and the LED or LEDs on copper, to damage anything inside the light.

thanks for the info!

vex_zg
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dw911 wrote:
vex_zg wrote:

I am though more concerned about the battery doing the thermal runaway.

so perhaps I need to do a test to verify if something will get damaged.

A quality cell should allow for non direct heating(say placing it in the oven, not attacking it with a blow torch) from ambience temperature to 130c for 60 minutes with no fire or explosions Smile

I feel safer now Smile

leaftye
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vex_zg wrote:
I am though more concerned about the battery doing the thermal runaway. so perhaps I need to do a test to verify if something will get damaged.


I can understand that.  I'm wanting to find a way to log temperature in my high current battery tests.  All I know right now is that some of them get hot enough that it hurts to touch and further shrink the wrapper, so I wait a few minutes before removing it from the battery holder.  

The low mode should be lower.

aoeu
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Boaz wrote:

 I wonder about hung lights vs tailstanding lights .

The heat hitting the battery harder since it’s above the emitter  . 

I heat only rises where a convection current can exist. So in liquids and gases yes, but solids no.

Comfy when you are saying you can’t kill a light on a single cell, is that assuming a certain light model, copper base, and good thermal paste? Or just in general?

B42
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I think in reality in setting the light down to run on max on its own, the more probable concern is more what could a running S3 set on fire if you set it on the wrong material, or had someone try to pick up the hot light and reflexively drop it…

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aoeu wrote:
Comfy when you are saying you can't kill a light on a single cell, is that assuming a certain light model, copper base, and good thermal paste? Or just in general?

On any of the single cell small pocket lights. Threaded pill, integral shelf, fins or no fins, doesn't matter.

I only use cheap white MG Chemicals silicon-based paste in the big bulk 10oz tube... I keep going on like a broken record about how at these power levels the Miracle Homeopathic Nano-Quantum Astrology Paste doesn't perform any better, but nobody wants to hear it.

wight
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comfychair wrote:

aoeu wrote:
Comfy when you are saying you can’t kill a light on a single cell, is that assuming a certain light model, copper base, and good thermal paste? Or just in general?

On any of the single cell small pocket lights. Threaded pill, integral shelf, fins or no fins, doesn’t matter.

I only use cheap white MG Chemicals silicon-based paste in the big bulk 10oz tube… I keep going on like a broken record about how at these power levels the Miracle Homeopathic Nano-Quantum Astrology Paste doesn’t perform any better, but nobody wants to hear it.

It’s impossible to have a sane conversation on this since neither side has empirical data. Or has that changed?

EDIT: Added my emphasis in the quote in case it wasn’t clear what I was referring to.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
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comfychair
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You can kill a LED on a non-direct-thermal aluminum MCPCB with a single cell even if said MCPCB is bolted to a 16-ton piece of copper.

comfychair
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wight wrote:
comfychair wrote:

aoeu wrote:
Comfy when you are saying you can't kill a light on a single cell, is that assuming a certain light model, copper base, and good thermal paste? Or just in general?

On any of the single cell small pocket lights. Threaded pill, integral shelf, fins or no fins, doesn't matter.

I only use cheap white MG Chemicals silicon-based paste in the big bulk 10oz tube... I keep going on like a broken record about how at these power levels the Miracle Homeopathic Nano-Quantum Astrology Paste *doesn't perform any better,* but nobody wants to hear it.

It's impossible to have a sane conversation on this since neither side has empirical data. Or has that changed? EDIT: Added my emphasis in the quote in case it wasn't clear what I was referring to.

I'm tired of trying to convince you guys that the blue sky is really blue, and not green. Sure, whatever, Tinkerbell is real. Happy?

 

 

wight
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comfychair wrote:

wight wrote:
comfychair wrote:

aoeu wrote:
Comfy when you are saying you can’t kill a light on a single cell, is that assuming a certain light model, copper base, and good thermal paste? Or just in general?

On any of the single cell small pocket lights. Threaded pill, integral shelf, fins or no fins, doesn’t matter.

I only use cheap white MG Chemicals silicon-based paste in the big bulk 10oz tube… I keep going on like a broken record about how at these power levels the Miracle Homeopathic Nano-Quantum Astrology Paste doesn’t perform any better, but nobody wants to hear it.

It’s impossible to have a sane conversation on this since neither side has empirical data. Or has that changed? EDIT: Added my emphasis in the quote in case it wasn’t clear what I was referring to.

I’m tired of trying to convince you guys that the blue sky is really blue, and not green. Sure, whatever, Tinkerbell is real. Happy?

 

 

Which do you think would make me happier, data or Never Never Land? The best data we have so far is from tests like this one by pflexpro, which does not directly address this topic.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
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comfychair
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Yes, good thread, unfortunately Fujik vs. solder is not the kind of thing I am advocating, not at all. Why do my arguments always get twisted around to "ha! he thinks we should all be using lights made of Fujik, asbestos, and styrofoam, lol!"

http://budgetlightforum.com/node/30532

Look at that and then explain how you get more light with excellent thermal paste under the star vs. average thermal paste under the star. The farther you get from the source of the heat the larger the contact area, which makes each joint less and less critical.

The substrate is pretty good stuff, but it will always be compromised since it also has to still be an electrical insulator.

But still, if there's no heat sag, how is a copper pill or better paste going to make more light come out? If the Tinkerbell theories are correct, why does a light with an aluminum pill and crappy paste not show any significant dropoff over time? The initial output is going to be the same no matter what since none of the downstream parts are saturated yet, right? So where in all this is the extra light output supposed to come from?

vex_zg
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are there any tests showing difference in emitter temps on copper star vs. Aluminum star? I’ve got some emitter l emitters on aluminum so it would be good to know what are the max currents/temps involved.

wight
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comfychair wrote:

Yes, good thread, unfortunately Fujik vs. solder is not the kind of thing I am advocating, not at all. Why do my arguments always get twisted around to “ha! he thinks we should all be using lights made of Fujik, asbestos, and styrofoam, lol!”

http://budgetlightforum.com/node/30532

Look at that and then explain how you get more light with excellent thermal paste under the star vs. average thermal paste under the star. The farther you get from the source of the heat the larger the contact area, which makes each joint less and less critical.

The substrate is pretty good stuff, but it will always be compromised since it also has to still be an electrical insulator.

But still, if there’s no heat sag, how is a copper pill or better paste going to make more light come out? If the Tinkerbell theories are correct, why does a light with an aluminum pill and crappy paste not show any significant dropoff over time? The initial output is going to be the same no matter what since none of the downstream parts are saturated yet, right? So where in all this is the extra light output supposed to come from?

I had some trouble following what you are saying in post #25. I’ve previously read djozz’s post you linked to. I glanced over it again just now. I’m still not really clear about what you want me to be looking for over there. Do you have a specific thing you want me to observe at that link?

[I understand the exact nature of what you are trying to express and I think that it is incorrect. I think I made a clear qualification when I linked to pflexpro’s post. It had nothing to do with twisting around what you were saying.]

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will34
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Not sure if applicable for flashlights, but here’s my experience with different thermal pastes:

When I was younger I was really into the self built gaming computer thing. When a high power processor, specially a video card was overclocked and pushed into high loads it produced an insane amount of heat, and can only lowered to decent temperature by the use of a water cooling system or a huge copper-base heatsink with massive fans.

When upgrading from a ceramic based compound to a high-silver one, I noticed up to 15° C drop at high loads. This drop might seem small but it gives plenty of room for overclocking.

BUT, we are talking about a processor which is much more sensitive to temp changes with an area much larger than any LED MCPCB, instant temperature raise on load, it could be idle @40° C and only seconds later at 90° C, this is really when the thermal compound plays an important role. A LED in the other hand is far less complex (greater heat tolarance) and doesn’t heat up as fast.

I have many times intentionally and unintentionally left a light on the highest setting and get an actual burn when touching it, and never killed one, or permanently reduced its output.

So in flashlights, I do think different types of thermal compounds makes a small difference, but in most, if not all cases these differences are so tiny that only exists in paper.

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If this is really the case? Why do we all obsess and observe measurable differences when using AL vs CU mcpcb? (Same goes for water blocks and heatsink a for computers.)
Fast heat or slow heat aguement makes no sense to me, it needs to get out.
Even when your computer is idle at 40C, it would be more like 45C if you used cheap thermal paste or applied too much, or had a poorly lapped heatsink, or a small fan, bad enclosure ventilation, etc.

It’s all part of a system that works together and every part makes a difference all the way to the end.

The faster the heat transfer, the better it is for the emitter, driver, CPU, ram, north bridge, caps, whatever it is.

When talking about thermal paste in a flashlight, yes it’s further down the line after the mpcbs, but it doesn’t mean that it doesn’t make a difference.

To each their own thoughts about the subject really.

End rant.

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The heat flux, or density - amount of heat load x contact area - is what's being completely ignored here. At low densities the quality of the paste becomes less critical. Down at the ~15 watt range, with a 16mm or 20mm dia contact patch, the paste's quality is irrelevant. If the cheap paste fills the voids, and doesn't dry out over time, it will not get any better than that with better paste. It just is not stressed enough for the on-paper advantage of the better paste to ever show up. Raise that to 200 watts, with a 1cm square CPU die, and the quality of the paste can be the difference between stable operation and failure.

Data is worthless if it is not applied to each situation correctly. Context is everything. I am not saying that emitter junction temperature is irrelevant. I am saying that the parts downstream of the LED's thermal pad, once the MCPCB dielectric is eliminated, can be really really poor and still be good enough to keep the junction temp low and stable - because the contact area between those parts is so large.

On paper, different solder alloys have very different thermal conductivities. As do different solder layer thicknesses. Yet, there is zero change in light output between 'bad' 63/37 PbSn and 'good' SnAgCu solder, or between a thick layer and a thin layer. How can this be, if these things 'really do make a difference'? If that were so, and these details resulted in a meaningful difference in junction temperature, wouldn't the 'good' setup give more light output? Why doesn't that happen?

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Just some info I found around the net…

Socket 1156 Intel I5 960 45nm Package size: 37.5mmX37.5mm
CPU die size: 296mm(2)
CPU to heatsink contact area: +/-30mmX30mm
CPU to heatsink contact area: +/-900mm(2)
CPU power stock: 95Watts

All this adds up to about 9.5mm(2) per Watt through the thermal paste if using the CPU cover to calculate Watts per area.
Or 3mm per Watt through the thermal paste if using CPU die size to calculate Watts per area.

Cree XM-L Package size: 3.75mmX3.75mm
Emitter to MCPCB contact area: 3.75mmX3.75mm
MCPCB to Pill contact area (16mm star): +/-200mm(2)
Emitter power stock: 10Watts

All this adds up to about 20mm(2) per Watt through the thermal paste

Pushing an XP-L to 6 Amps would get it to 10mm per Watt through the thermal paste.

To further discuss…
I am not accounting any heat losses through other means… but it does show that you may be totally right comfychair. But then I think about that huge fan blowing air right on the CPU heatsink cooling it down way faster than the body of a flashlight ever could.
I am not saying that cheap thermal paste is not up to the job, just saying that to my limited knowledge, it could possibly make a difference.

B42
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comfychair wrote:

The heat flux, or density – amount of heat load x contact area – is what’s being completely ignored here. At low densities the quality of the paste becomes less critical. Down at the ~15 watt range, with a 16mm or 20mm dia contact patch, the paste’s quality is irrelevant. If the cheap paste fills the voids, and doesn’t dry out over time, it will not get any better than that with better paste. It just is not stressed enough for the on-paper advantage of the better paste to ever show up. Raise that to 200 watts, with a 1cm square CPU die, and the quality of the paste can be the difference between stable operation and failure.

Data is worthless if it is not applied to each situation correctly. Context is everything. I am not saying that emitter junction temperature is irrelevant. I am saying that the parts downstream of the LED’s thermal pad, once the MCPCB dielectric is eliminated, can be really really poor and still be good enough to keep the junction temp low and stable – because the contact area between those parts is so large.

On paper, different solder alloys have very different thermal conductivities. As do different solder layer thicknesses. Yet, there is zero change in light output between ‘bad’ 63/37 PbSn and ‘good’ SnAgCu solder, or between a thick layer and a thin layer. How can this be, if these things ‘really do make a difference’? If that were so, and these details resulted in a meaningful difference in junction temperature, wouldn’t the ‘good’ setup give more light output? Why doesn’t that happen?

I think people are getting confused on the idea of the difference between pastes at this particular scale and thickness is not enough to see, and confusing it with the idea that “there is no difference at all” between pastes.

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