makes sense when u think about it, such fans even if 3 in that head can they really push out that much heat fast enough? probably not… but who knows.
Not at all. Based on my calculations, it just might be able to do 40k lumens continuously. It’s kind of at the limit.
Now 30k continous is definitely doable.
So if 40k lumen is borderline, I could definitely see it doing 40k for at least 5 to 10 minutes, then step down to 30k for the rest of the batteries life.
Even this is a huge step up from the 7k continous lights we currently have.
But once the batteries drop half their capacity, the volt isnt too low too keep up that much lumens? im skeptical… my olight x9r i cant do 2 highest modes once battery shows 4 bars out of 8 left… ?
I’m sure the output has to step/ramp down once the batteries start to drop voltage. This is normal.
Care to share your calculations?
Considering the XHP70.2 thermal resistance of 0.9C°/W and a max Tj operating temperature of 150°C, with 29W input, and 23°C ambient, this would mean the heatsink could be allowed to rise 100°C above ambient, yes? Though the LED output would be reduced to 85% of the rated maximum at this Tj. To maintain 85°C Tj, the heatsink would only be allowed to rise 36°C? This is probably overly simplistic. Will dig into the requisite math more later.
DX80 only does 7000 lumens continuous? Or are you talking about a different light?
With the very basic understanding I have of this matter, you are not wrong.
I think that with 3 fans it would be possible to keep the heatsink at a decent temperature, let’s say 100°C. Even if the fans can’t handle it the time it runs on full power is extended. So it’s a win nevertheless.
The lack of surface area to dissipate heat will make the fans less useful, and the few fins on the X70 are pretty thick based on the picture. If they used a CPU style heatsink it would be a whole different story.
I used this heatsink with a CXB3570 @ 85W and it was just warm to the touch. The fan was running at slow speed drawing less than 2W. I can see the potential here and possibly keep the temp at less than 65C at full speed even if we triple the load. https://www.amazon.com/gp/product/B00606OHQQ/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
The problem with acebeam is they insist on using small fans with tiny propellers with relatively low CFM, even 3 of them can’t compare to a properly sized fan.
I think this would be a more effective solution: fresh air is drawn from the back and exits through the emitter side (sorry for the quick paint job) 
Looking back at my older posts in this thread, I think Acebeam was shooting for 30 minutes at 40k lumen. Then it would have to reduce output. Does anyone remember Acebeam saying this?
Yes, DX80 seems to hold the record followed closely by the Acebeam X65 which does about 6k continously with air circulation, 5300 in still air.
Maiden666 tested it. It will do about 6k lumen in a room with no air circulation. About 7k if a fan is turned on (which I think is equivalent to walking around with it outside). I talk about it here.
We have not seen their heatsink or fins. Where did you see them? I think they may be using something very similar to cpu heatsinks.
The X70 fans (3 x 30mm or 40mm) are mounted vertically. There is room for a ton of surface area to dissipate heat.
Actually the x9r can do 6400 nonstop until battery runs out so it beats both the dx80 and x65.
Mortuus, you should know better. We don’t go by rated specs. We go by real world tests.
Let’s wait until it has been tested to see if it can do 6400 lumen continously.
BTW, this is still less than the 7000 lumen continous of the DX80.
Agreed, it’s all about real world tests. Advanced Knife Bro tested the DX80 at ~7000 lumens for 2 hours. Has anyone done a real world test on the X9R? I’d be interested in the results.
I haven’t seen any, although I haven’t really been looking. I’m sure we’ll see some tests soon.
TL:DR: It’s possible.
It looks like they are running the LED’s at max CREE recommended specs. Assuming that, the XHP35 is putting out 1830 lumens, the XHP70.2’s the other 38k. so 38,170/12 = 3,180 lumens each. If their 40k lumen figure is OTF and not emitter lumens, it would appear they are running the led’s at max factory specs, which CREE claims is 3,800 lumens for the XHP70.2’s and 1833 for the XHP35.
That’s 13 watts for the XHP35 and 29W for each of the XHP70.2’s. Total wattage in that case would be 361 watts. It’s commonly said that between 60-75% of the energy going into an LED turns into heat. Say 60% of the energy turns into heat going into the heatsink, that is 216W of heat. Around 200W+ of heat needs to be dissipated.
So, the LED’s can run very hot, you could run them at 150C Tj continuous, but of course the batteries and the flashlight cannot be allowed to get much above 60C. Decoupling the head from the body with stainless dowels or what not would allow the head to become much hotter than the rest of the light, or decoupling the heatsink more or less from the light is an option. Either way, the target temp for the heatsink can be considered independently.
The XHP70.2 has a thermal resistance of 0.9°C/W, the XHP35 is at 1.8°C/W but runs less than half the wattage so it comes out the same thermally. So if the XHP70.2 is being fed 29W, it is 26°C above the heatsink temperature. Combined with the ambient temp, this allows about a 100°C rise in heatsink temperature before the LED Tj is at 150°C.
What does a commercial actively cooled fansink rated for 200W heat dissipation look like? The MECHATRONICS LED ICE ULTRA is an example of this.
The datasheet says that this heatsink will have a 50°C temperature rise over ambient at 200W dissipation. With this heatsink, at 23°C ambient, the Tj of the LED’s would be 99°C. That heatsink appears to use a 90mm to 96mm fan and consumes 2.76W at 3,000 rpm. They don’t spec it, but it probably has an output of around 55-60 CFM and >0.15” H2O or so. The heatsink resistance is .25°C/W, so this means it could dissipate 400W of heat before a 100°C rise occurs.
What do their smaller heatsink models looks like? Two of their smaller ones are in this datasheet. The difference between the two heatsinks in this datasheet is 10mm in fin length. Their thermal resistances are .58° and .46°C/W between the two. Its about an inch shorter than the 200W heatsink, and the ~90mm fans are 1500 rpm rather than 3000, but the heatsinks are the same 100mm diameter. These fans should be putting out around 30 CFM and .04” H20 SP. The bigger of the two fansinks could handle 200W before a 100°C rise. They do not have tightly grouped fins, presumably so that dust is less of an issue, and this is appropriate for the fans which do not have high static pressure.
If the fans in the X70 are high rpm 30x30x10mm fans, which they definitely don’t look like 40mm fans, they are putting out around 8 CFM each and 0.380” H2O (94.6 Pa) static pressure. Static pressure can be additive as well as cfm, so you’ve got 24 CFM and ~1” H2O static pressure. It’s a decent amount of static pressure; I have a loud and powerful 40mm fan with those specs. This means that the fins of the heatsink can be thin and tightly spaced.
So, what is clear is that the heatsink and fan combination needs to have better than .5°C/W sink to ambient thermal resistance (aka theta sa) to keep the heatsink from rising 100° above ambient, if there is 200W of heat to be dissipated. .4°C/W theta sa would be better, with an 80°C rise.
After looking at a lot of fansinks and specs, it would appear that it is possible that there is a .5°C/W theta sa or better conventional fansink within the volume in the cavity of the head of the X70, especially if it’s copper. (example at .55 theta sa at 26 CFM)(example at .3 theta sa at 26 cfm) The questions are: is there a high density aluminum or copper heatsink of sufficient volume hidden within the cavity of the head of the light? Do the fans deliver 20+ cfm? Are they really feeding those LED’s 361 watts? And so on.
Wattage for the xhp35-HI might be double your 13W. So 26W sounds about right.
I calculated about 270-300 watts total.
I think we’re both in the same ballpark. If outside on a 70°F day with some wind it might be able to go continous full power without stepping down.
That’s not quite right, you can either parallel the fans for more flow or have them in series for more pressure, but not both. Great explanation otherwise :+1:
Based on the orientation of the three fans, I assumed the heat sink fins would be divided into 3 sections with one fan for each.