Update: 10-22-17. KRONOS K70 GB. $50. 243 on list!

[PineyJustice]

I’ve got a couple 26650s sitting around doing nothing, why not

In.

[Gerrh]

Put me down for two please: )

[gastonpatagonico]

S70, it’s already there !

[billoz]

I’m in for one. Thanks looks great !!

[KawiBoy1428]

Really interested in this part….

The KRONOS K70 was designed in cooperation with ThorFire, and based on their beastly S70. Originally, we only planned to upgrade the internals/UI to fully realize the potential of this light. We soon came to the conclusion that a re-design of the host was also needed to overcome some design issues with the original S70. Therefore, the KRONOS K70 is not just a simple re-design, but a new light with plenty of oomph. Our goal is a walloping 8-9 amps!

Please check out the prototype/development pics. We will update with pictures and specifications after samples are received and tested:

Wondering if it had something to do with this part of the design?

Care to elaborate?

[DB_Custom (Dale)]

Look at the cutaway drawings Kawi, it’s still made that way…

[KawiBoy1428]

2 pc. Head yep! Talking about the amount of material removed from the shelf, you only need 2 lead access holes and 2 hold down holes. If I was making a XHP70 Hot-Rod I’d want a full shelf, that’s just me. Unless I’m missing something in the rendition cut away?

Just wondering…….

[D10ten]

Definitely in for one!

[yasenf]

In for one, please.

[Saigon]

interested in one

[OrangePeel]

Hello,
Please add one for me.
Thanks

[shan6oob]

interested in one …

[Yokiamy]

@Fritz15

+1

I was thinking that is exactly what the C8 makes such a good light, fins on the right place, good construction, good heat transfer especially the new type with integrated shelf, so this might be a good guideline for manufacturers, instead of trying to re-invent the Wheel.

[Richie086]

I’m in for one also. Thanks.

[JasonWW]

@fritz15

@JasonWW

@DB Custom

I’ve seen thermal imaging tests taken as a light was turned on and in the first seconds as the heat made it’s way through the heat sink. They said the pattern was almost exactly an inversion of the light coming out the front, so if you consider the light out the top as the top half of an X and the heat out from under the emitter as the bottom half of this X, you see where the heat needs to go for fast and immediate dispersal.

I have to disagree with you on this one, buddy. Heat does not flow directionally like in your picture. When the emitter heats up that copper MCPCB, the heat gets spread across it very evenly. Not perfectly, but decently. This is why larger diameter MCPCB’s do a better job at transferring heat.

Once that copper disc gets hot, the heat transfers into the aluminum below it and starts spreading out evenly like a drop of water on a sponge. Areas that are thick will take longer to heat up than thin areas. This means the thin areas will get hotter first.

Did you see a thermal image of a flashlight cut in half? I’m guessing it was a whole light. What you probably saw was the battery tube and other thin areas down low start to “heat soak” so to speak, while the thicker areas around the head was still soaking up the energy (heat).

The photo you show pretty much proves that. Thermal imaging shows actual temperatures. The fact that the temps were lower around the thick sections all around the emitter shows this design is doing it’s job and keeping things cooler.

Does that make sense?

While I don’t completely agree with either of you I support DB Custom’s point that the cooling fins aren’t in the best place. The way heat spreads out is comparable to how a liquid without gravity would flow (imagine the liquid has it’s source right under the LED). It goes into the direction of the smallest resistance. So the first few cooling fins are pretty deep and I am sure you would see a better thermal performance if they’d not be as deep. When designing the BLF GT we also did extensive thermal analysis and the results were pretty clear - having the fins distributed around the shelf yields a significantly better thermal performance compared to having them above the shelf (here we even disregarded any transitional resistances). See the following thermal analysis of a BLF GT design with fins around the shelf and fins above the shelf:

Edit: Also, the thicker the walls, the more evenly the heat gets distributed and more heat can flow away from the source. Again, think of the liquid, the thicker the walls the more space there is for the liquid to flow away.

I agree that you want more surface area (fins) near the heat source as this will increase heat transfer through radiation. This slows down and hopefully limits the max temperature of the flashlight.

To sum it up, lots of mass around the heat source helps transfer the heat through conduction (from LED into the metal), then lots of surface area around the heat source helps transfer that heat through radiation (from metal to surrounding air).

Please don’t use an analogy of liquid spreading in zero gravity. This is way off. Liquids, like water, in zero G don’t really spread, the surface tension keeps it together as I’m sure we’ve all seen videos of astronauts playing with water. It’s a bad analogy and may confuse others. It certainly confuses me, at least.

[JasonWW]

@fritz15

In order to really understand what we are seeing here, we need a cross section view. (I could flip flop the thermal images from these same exterior designs just by manipulating the internal shapes)

Also, where these images taken after the same time frame? I assume so, but want to make sure.

[hIKARInoob]

I think one thing to take into consideration is that the above does not solely compare thermal properties of fins between led and reflector vs fins between led and batteries. The two lights are of a slightly different design as well. For example, the fins on the cooler running light are deeper.

[DavidEF]

@hIKARInoob

I think one thing to take into consideration is that the above does not solely compare thermal properties of fins between led and reflector vs fins between led and batteries. The two lights are of a slightly different design as well. For example, the fins on the cooler running light are deeper.

I think you’re misunderstanding the picture. The “cooler running” of the light on the left is a BAD thing! For the best performance, the heat should be pouring out of the light, like the one on the right.

[JasonWW]

@DavidEF

I think you’re misunderstanding the picture. The “cooler running” of the light on the left is a BAD thing! For the best performance, the heat should be pouring out of the light, like the one on the right.

This actually depends on the cross section views and how much time has elapsed in these images.

If these shots are after 30 seconds and the light on the left has more mass around the heat source, then it is clearly the better thermal design.

If these shots are after 15 minutes and both lights have the same thermal mass, then the light on the right has the better thermal design.

Thermal imaging shots like this are not the best way to judge a design. They are helpful, but not the best. The LED temperature is the crucial factor and that is not shown here. Whichever light has the cooler running LED of these two images is the better thermal design.

[fritz15]

@JasonWW

I agree that you want more surface area (fins) near the heat source as this will increase heat transfer through radiation. This slows down and hopefully limits the max temperature of the flashlight.

To sum it up, lots of mass around the heat source helps transfer the heat through conduction (from LED into the metal), then lots of surface area around the heat source helps transfer that heat through radiation (from metal to surrounding air).

Please don’t use an analogy of liquid spreading in zero gravity. This is way off. Liquids, like water, in zero G don’t really spread, the surface tension keeps it together as I’m sure we’ve all seen videos of astronauts playing with water. It’s a bad analogy and may confuse others. It certainly confuses me, at least.

Yes, good summary, ideally a large, high powered light has both, a lot of mass around the heat source and also a lot of surface area.

The analogy is good enough to illustrate where and how fast the heat will flow in the host. I think you might have misunderstood me. You are right that it does not make sense to talk about the distribution of a constant amount of water. But if you place your water source right under the MCPCB and fill up the host (where there would be usually aluminium) then the way the water spreads is similar to the way the heat spreads.

@JasonWW

In order to really understand what we are seeing here, we need a cross section view. (I could flip flop the thermal images from these same exterior designs just by manipulating the internal shapes)

Also, where these images taken after the same time frame? I assume so, but want to make sure.

The shelf temperature would be enough (which was also quite a bit lower for the better design). Not without restricting the self thickness or some other awkward design changes. The point of this comparison was to see the performance of two designs with different fin location and the same internal designs. Yes, since it is one thermal analysis. The image displays the equilibrium state of the heat distribution.

@hIKARInoob

I think one thing to take into consideration is that the above does not solely compare thermal properties of fins between led and reflector vs fins between led and batteries. The two lights are of a slightly different design as well. For example, the fins on the cooler running light are deeper.

The slight changes in design are not relevant for the point, which is that cooling fins right around the shelf improve thermal performance.

@DavidEF

@hIKARInoob

I think one thing to take into consideration is that the above does not solely compare thermal properties of fins between led and reflector vs fins between led and batteries. The two lights are of a slightly different design as well. For example, the fins on the cooler running light are deeper.

I think you’re misunderstanding the picture. The “cooler running” of the light on the left is a BAD thing! For the best performance, the heat should be pouring out of the light, like the one on the right.

No, it is a good thing. The left design is better since the fins are located where there is the biggest amount of heat. That means the temperature at the fins is as high as possible which allows for an as good as possible heat exchange between air and host. The higher the temperature difference between host and air the better the heat exchange works.

I am sorry I caused quite some confusion with the picture. Long story short, there should be fins around the shelf for an optimal thermal performance.

I’ll see if I have a comparison with the two shelf temperatures somewhere floating around, then it should be more clear.