[quote=Lightgecko]
Hold on to it tightly as well. As it turns out, your hand (or rather the blood flowing through your hand) works pretty effectively as a radiator, helping move heat out of the light. /quote]
I must disagree with that I’m afraid. The surrounding air will dissipate the heat faster than essentially insulating the light with your hand. I sure as buggery wouldn’t grasp the fins tightly to try and cool a torch. I do the complete opposite and hold as far away as practical from the head.
I must disagree with that I’m afraid. The surrounding air will dissipate the heat faster than essentially insulating the light with your hand. I sure as buggery wouldn’t grasp the fins tightly to try and cool a torch. I do the complete opposite and hold as far away as practical from the head.
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Look up the thermal conductivity of air. It’s a much better insulator than your hand is. I completely agree with you that fins allow air to cool the light due to the increased surface area, however on the rest of it where there aren’t any fins holding it will help pump out some more heat. I don’t mean that it’s better than a good solid heatsink, but it does help.
In the massively overdriven tiny lights like an XHP-50 in a AA light with two 14250s in direct drive, there’s just not enough thermal mass avuailable, and you have to really hold on to it tight. The coolig effect is much more noticeable.
Remove as much alu from the LED shelf as possible to let air pass
cut away material in two lines, the ones marked with red just seem the only ones possible
this creates holes for cool air to be sucked in (bottom) and hot air to be pushed out (top)
The more mass there is, the faster the metal emits heat as infrared light. For what your’re trying to do, passive cooling is fine. In my few high power builds (higher than your 25w) I have no active cooling and they’re all still fully functional.
Go look at some of the members who are more talented than me and their ridiculously overpowered builds. Only a handful require active cooling, and even then more than just a fan blowing through some holes.
What I and what i think other members are trying to say is that even with a fan, you still need more metal to sink the heat away from the emitters and to provide enough surface area to allow airflow to effectively remove heat. Just pointing a small fan at the emitter star on a thin aluminum shelf won’t work any better than plain passive cooling.
But adding active cooling is indeed a fun idea.
Could a fan be powered in series with the leds (those are in series)?
Higher brightness higher fanspeed.
In this light there is no “shelf” the leds are soldered to a 1.5 mm plate that only touches the housing at its very edge of about 1-2mm so the reality is there’s basically no thermal transfer to the housing. Also if you look at the right light ( not the one people keep posting here ) there is pretty much no finning on the housing so that even if you did transfer the heat to the housing it would struggle to dissipate it.
This is why im going to install the biggest copper heat sink and active cool it, too cool my 25 watts. Also there seems to be many posts suggesting that the lights get very hot and can’t be used long term.
The leds are in parallel. i have pondered on what to do about fan speed i think i’ll have to step up the voltage to get the fan to actually do anything. This does mean it will be a fixed speed.
Based on the running time and thermal management system of real-time temperature detection. When the flashlight is on high brightness mode, the first 5 minutes the output will keep full brightness. In the subsequent 5 minutes, the output will gradually drop to 50% of the initial brightness.
And previously mentioned i have a real 8 watt LED and it gets to hot to hold.
Sooo heating is a real problem … well it is to me. At the very least the cooler you keep the light the more output you’ll get so that alone is a good reason for some good thermal managment
At this point the plan is to drill some inlet holes at the end of the light so cool air comes in and goes past the hand grip first to keep it cool. then out near the led’s star … on my light thats on the collar where the switch is.
If you put a fan in the driver area you will have the problem of the led wires, the fan must fill the cavity to work efficiently.
Not too big a problem, just more work, as you can put in a collar with holes for the leads then mount the fan in the collar
Also you could fix a finned heatsink under the shelf to give you more surface area.
13500 lumens would require around 200w. I’m guessing your using stock leads on your multi meter so you’re unable to measure more then 1.5 amps. If your Skyray was really running 1.5 amps that would put it at 6w, so a BLF A6 would be brighter then ur 9x led Skyray.
The limiting factor with flashlights isn’t heat its voltage sag. The shelf was originally removed from Skyrays because people complained about the heat, so they removed the shelf and the heat problem was solved!
Unless you plan on fitting a small CPU heatsink under the shelf you will find the PCB will generate heat faster then a fan could shed heat from the heatsink, and at that point you could of just added more mass and gone down a mode! Whatever you decide i’m sure it will be fine 25watts is what most stock soup can lights do.
Have a read around theres plenty of information here:
errr no it’s not the multimeter limiting it at 1.5 amp thats nothing. In any case it’s no brighter if the meter is not involved. Also i have a 100W resistor that’s .47 ohms so i have applied a voltage and measured the current and it’s what it should be. I didn’t run it at 100Watts cos there’s no need for this example. The issues with multimeters is when low resistances and high currents are involved than this.
This light is a complete fake light.
i would put money on them fixing heat problem by moving to fake LEDs and therefore the current is not pulled and therefore it doesn’t get hot. AND OR by removing reducing it’s ability to move the heat to the body by giving it a piddly shelf and they just let the leds get extremely hot, but what do they care.
BTY for those of you who are in the add more mass camp. Me adding a copper heat sink will be increase its mass.
I actually have an SRK I’ve been debating going with an internal heatsink and fan or just a block of copper. The heatsink would be machined from aluminium and replace the whole board, vent holes in the side with a small fan mounted in the center of the heatsink. Divider separates the heatsink from air intake section to keep fresh air cycling in. Driver is potted and sealed around other edge with silicone, as is the wire hole through the pill. Fan won’t be waterproofed but will probably hold up long enough, or I could coat it as well. Really the main reason I am interested is because it would be cool.
For most applications fan cooling just isn’t practical. Fan cooling is only really better with continuous use, intermittent use thermal mass is fine. And if you have a light that needs fan cooling then chances are your runtime is quite low even with a multicell host like an SRK. So what exactly is the use for such a light? As it is crazy lumens is not really much more useful for many applications than 1-2k lumens. Then you have the weather issues or water/mud/dirt getting inside and causing all sorts of havoc. Now I should be clear I LOVE building totally impractical lights that just dump out as many lumens or kcd as possible but for the average user and many modders they want a reliable and practical light that is pretty bright when needed but is normally used on lower settings with a good balance of output and runtime.
If you’re that concerned about heat, consider how much air volume you’ll need to push through the light body in order to cool it. As I previously mentioned, air is an insulator. It does not want to conduct the heat away. For effective cooling, large flow rates are a requirement. Holes drilled in the light tube aren’t going to facilitate that great of a flow rate. That means your fan is going to have to have some serious power. Even with 4 of the best 18650s available it will only run for a little over 2 hours at 5.6 amps.
You do seem rather determined to put a fan in it. I just don’t see the necessity. I hope it works out for you.
I partly agree with you Lightgecko, some serious work would be required to get the fan to have an appreciable effect but I think it’s certainly possibly in an SRK format. My plan was first to improve the heatsinking from the LEDs to pill (direct MPCB) and from pill to body (press fit in head or perimeter bolts to the shelf) then add the fan and lots of holes or probably milled slots. You do need some decent airflow to dump that much heat but consider many laptops that have similar or smaller heatsinks and fans. The difference between the fan on and off pretty significant. Not so much on newer laptops with efficient Intel CPUs but some older AMDs put out some serious heat and any blocking of the airflow got serious quick. I mean something like heatpipes running down the side of the light is really probably a more practical plan than fans if you really want to do some special thermal system. Say a 26650 light running 18650s and an aluminum spacer with heatpipes pressed in the body and sitting against the MPCB.
Yeah I think it’s just the age old struggle between possibility and practicality. I know exactly what you mean with the AMD part. My old laptop got so hot the spec stickers started to peel. Yeah it doesn’t work so great anymore…
I think people should look at this like so. Im adding cooling im not taking anything away form the original design so it will help. Adding fans makes a huge difference to everything cos you’re now moving the hot air away.
For long running it will be far more effective than increasing mass but as i’ve said me adding a heat sink is adding mass.
At the end of the day adding a fan is far more interesting to me as it will be much harder.
