Suggestion for Led driver: monster spotlight!

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Ollie
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Texas_Ace,

I think I understand that. This brings me to my question: LEDs project heat to the front. So I'm looking at my Manker U21 with its aluminum reflector. Now, I also have an aluminum reflector for a Mag, don't remember where I got it. But such a reflector must be absorbing some heat. I have a 70.2 build coming up, and I thought about using this to suck away some heat. I get an acceptable beam with the deep Mag reflector, but it does nothing for heat transfer. Then another thought occurred to me. Does an optic absorb heat (to some degree of course), or does it prevent heat from radiating away from the LED? One of my other hare-brained schemes is a Mag with three of Richard's triple XP-G2s. They're wired parallel, so I would connect the MCPCBs in series, 3S3P. I'm going to try running 4 C NiMHs in a 3D. I've had them in that light before. I'm going to use the 10507s, hoping to get at least some hotspot. But are they causing a higher emitter temperature?

Ollie

Texas_Ace
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An LED has most of it’s heat directed backwards into the mcpcb, only a fairly small amount of the heat is sent towards the front (around 30% depending on many factors). So the heat sent forwards is not really worth thinking about, it travels with the light photons and is projected on whatever you shine the light on. Many of my lights can project noticeable heat 5-10 feet away.

The heat we are worried about is what goes backwards through the mcpcb. This is why we want DTP copper mcpcb’s and good cooling paths with lots of surface area to dissipate the heat.

The maglight doesn’t have very good heat shedding so be careful going too crazy with it. I just built an M6 with more mass then a maglight running 4 triples and making ~13k lumens. It gets scary hot in about 90 seconds, I say this with my EDC light getting to around 140f in 90 seconds or so.

The Second Amendment is in place in case the politicians ignore the others.

Government is the great fiction, through which everybody endeavors to live at the expense of everybody else. -- Frederic Bastiat , French economist(1801-1850)

Texas Avenger Driver Series

My LED Test series - XP-L2 V5  - Nichia 219C 90+ CRILatticebright "XM-L"XHP35 & PWM efficiency - XHP50 - XP-L V5 - XM-L2 U2 - XP-G3 S5  - XP-L HI V2 - Oslon Square & direct comparison to Djozz tests - Nichia 319A - Nichia 219B 9080 CRI - Nichia 219C D320 - Nichia 229AT

How I made a True integrating PVC sphere with no math involved

leroycp
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…and if you decide to experiment with multiple drivers kaidomain has a number of beefy bad boys…given you figure out the power aspects.

Ollie
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Texas_Ace,

Heat shedding is where you find it. I think that with a single emitter build, a solid chunk of copper pays dividends. I think the material is of lesser importance with multi-emitters. Case in point: 5-6 years ago I built 2 quad XM-Ls, and I used aluminum. The way I did this, I machined the main body of the heatsink to closely fit the inside of the Mag tube, But on top, I left a little hat measuring .250 thick, extending out .105 from each side. This makes assembly somewhat different, in that you screw the head onto the body, and then insert the heatsink. So the heat from two of the emitters is directly over the widest point of the top hat, and this is directly over a flat portion of the head right next to the threads. The heat from the emitters will warm up the heatsink, as per normal, but will also take the path through the brim of the hat, right to the head!

If I got my dimensions right years ago, screwing the head down over the light will clamp the optics to the PCBs, and them tight to the heatsink. I am toying with the idea of not gluing them, but just using heat transfer goop, as KD does.

Here's where I come down on the mass vs surface area question: I think mass is paramount. This is why bench testers affix their stars to big chunks of copper or aluminum. It is as if you have a bucket that you are pouring heat into. The bigger the bucket, the more heat you can pour into it. In the real flashlight world, as the bucket is filling, the heat you are making is reducing as the batteries are depleting. We don't fry emitters at the 10 minute mark, generally. We kill them in the first 2 seconds because the heat we are generating is beyond the thermal conductivity of ANY material we might use, starting with the copper star. When we get to the surface of the flashlight, realize that we are trying to emit heat through one of the best insulators, air. The only fins that are of much use are the ones attached to fish, but fish are notoriously difficult to solder. When we say "Wow, feel the heat on those fins on the flashlight", we are making an observation based upon the heat transferring to our skin and blood, which are much better conductors of heat than air. Absent transfer to a better conductor than still air, you are better off with as much mass as you can tolerate. This is why automobile radiators have fans. Without a fan(s), there may be no way you can keep an idling car cool. Trust me, in my much younger days I pulled the fan off a car to avoid the parasitic horsepower loss. It worked, too, until one night I got stuck in traffic. Fail!

Anyway, I plan to orient the triples with the wiring connections closest to the outside if the head, and route the wires to the outside, just to be tidy, and run the end + and - wires down through the center hole. I am not looking to compete with one of your firebreathers. 1.5A to each emitter will make me happy. This should be what, a range of 45-50 Watts? I think that's about as far as I want to go with a Mag head. That could be close to 6000 lumens, before optics losses (S4 3D). I'll be really happy with anything close.

Ollie

Texas_Ace
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Thermal mass is good for flashlights since it gives us a longer runtime before it gets too hot to hold but besides that it doesn’t do anything. Surface area is what matters for dissipating the heat to the air.

A lot of guys get hung up on copper vs aluminum. I personally don’t really care in most cases.

The one thing that I do want to see in copper is the DTP mcpcb. This is well worth the minor cost increase for the benefits. The flashlight itself I don’t really care what it is made out of.

I like copper spacers in EDC triple builds simply due to the higher thermal mass adding a few extra seconds before thermal step down kicks in. In larger lights I prefer aluminum as it is lighter and usually leads to a more balanced light.

The Second Amendment is in place in case the politicians ignore the others.

Government is the great fiction, through which everybody endeavors to live at the expense of everybody else. -- Frederic Bastiat , French economist(1801-1850)

Texas Avenger Driver Series

My LED Test series - XP-L2 V5  - Nichia 219C 90+ CRILatticebright "XM-L"XHP35 & PWM efficiency - XHP50 - XP-L V5 - XM-L2 U2 - XP-G3 S5  - XP-L HI V2 - Oslon Square & direct comparison to Djozz tests - Nichia 319A - Nichia 219B 9080 CRI - Nichia 219C D320 - Nichia 229AT

How I made a True integrating PVC sphere with no math involved

Dimking
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kiriba-ru wrote:
Dimking wrote:
2P35S for direct drive.
vice versa, 2S35P

That’s what I wanted to say Smile

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