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Wow….magic smoke. I guess it’s pushing physics a bit too much.

I have the JKK76 SFN55.2 (different LEDs of coz) and one thing i noticed in both the lower modes and turbo against say an Amutorch DM70 with Cree 70.2s is that the chinese SFN 55.2 seems noticeably less efficient. So to get more lumens, you’d end up with even more heat, and we also know that as we overdrive things and push the envelope like this on a relatively light host (i think the JKK76 has nearly twice the mass), we really hit a brick wall with the law of diminishing returns. Not sure about driver efficiencies between the Amutorch and JKK76, but i guess we’d just have to assume that they are very similar.

I already saw that on the video on NW’s TB page on the sag, some sort of sag….be it heat somewhere, or battery. Comfortably 30k+ on turn on with the Lishen 21700HP but 2-3 seconds on it dropped to 25k lumens.

The saving grace is that this was 319rmb when it was still available till very recently, i think it sold out ard mid or end of Apr. JKK76 is 538rmb now. (428rmb launch price like 1-2 months ago?)

And if i remember correctly, Nighwatch packages 2pcs of LS 21700HP in it as well, so you are good to go if you ordered from TB (countries serviced by TB’s official forwarder CaiNiao can do that……and yes technically able to ship out as long as you can checkout on TB platform….shhh…with regards to li-ion cells. You cannot buy listings that list say 21700/18650 by themselves). With using only 1 cell, i found that the Lishen 21700HP outperformed my Samsung 40T in terms of output/sag at very high current draw on the 3-cell JKK76 during testing, check the JKK76 thread on this. So….319rmb all in, really incredible value.

ps. sucks regarding the cell wrapping killer for some batteries too.

Just some 2 cents from a regular flashaholic end-user. :beer:

To be fair, they’re domeless LEDs :stuck_out_tongue:

It’s also possible there are more internal bottlenecks.

I just tested mine in industrial enviroment aka powerplant. Lots of poorly illuminated places and shadowy corners. This thing brought light to places that haven’t seen it in decades. Also gets hot very fast. I mean really hot. I added spring bypass to mine, because it was so easy to do cleanly and with these currents it can’t be useless.

Like this:

Possible that if the bypass does make a difference, but it might also do this. Higher lumens before step down period, but faster step down.

I was posting that for the JKK76, if it were able to do well over 33k lumens with good cells….this might happen. So there is a trade off. With below video, i guess it’s sorta confirmed with these chinese LEDs.

edit - also for Audril, at least we can play with and change the thermal limits, whether that makes a difference in reality remains to be seen.
Nighwatch/Jinheng/Haikelite/etc stuff cant.

ie yes, say if we can push the FT03S to nearly 10k, but at what cost. The FT03S is just a wee bit lighter than the NW Chaos i think, perhaps for the head portion where it matters, there is no difference.

Yes, probably faster stepdown. But I think this is just the light for trying to maximize the oomph if only for a short while. There is always dimmer modes if I need sustained illumination.

Do you have before and after bypass figures? Seems like the original spring design is already “bypassed” by that tab, which of course you bypassed in parallel again with that wire of yours. :money_mouth_face:
Or perhaps have you measured on the meter how long in turbo can it hold? Be it before bypass or after bypass.

On this topic, realised now that this light is only 336g.
That means it is in the 8k lumens per 100g range.
Plus the efficiency is somewhat lower than the Cree LEDs.

I measured resistance of the tail spring assembly before and after the bypass. It reduced the resistance for about 40%. I haven’t taken any other measurements.

Wow…….that’s rather significant. Coz i have also done some bypass on my JKK76 but i didn’t do any readings on the luxmeter or be bothered with anything as i wasn’t expecting any results….the kind of “just do it and be done with it” thingy.

The JKK76 steps down in around 30 seconds. Just about at my personal limit of turbo usage, i really cannot imagine anything less than that. Coz after turbo, it’s pretty much saturated, can’t do much with the flashlight for a good few minutes other than using it in the lowest mode. At least for the Amutorch DM70, that has a handle…if we are talking about using a hot flashlight comfortably for minutes.

What i do if i am at home is to immerse 3/4 of the light into a mug of water if i wanted more play time. :sunglasses: :person_facepalming:

Those resistances are already small, so it might be that my budget meter isn’t excatly the most accurate. It’s Aneng 8008 or something.

Yea, perhaps so. Mine isn’t also, UNI-T lowest range model. So best is to use a luxmeter, that one is very sensitive to differences for what we are using it for……more than sufficient actually. Coz the luxmeter also takes into difference the battery cell sag, internal impedance and things.

Maybe one day i shall remove my alu foil bypass and test it out for such styles of lights. Of coz, not expecting very significant differences to the layman, but like in that youtube vid (Cheule’s flashlights review) it still would interest the crazy flashaholics like us. lol :smiley:

I know other lights (eg BLF Q8) it does make a difference, just not sure for this style and power range / quality of materials etc

Some quick measurements:

A bypass would make a huge difference and on mine it’s bypassed from the factory. I got 51 amps at start on mine.

For the record, you can’t really compare the xhp70.2 with these SFN55.2 or sfq55 LEDs. They are nowhere near as efficient and the 70.2 is 4-die emitter. The SFN55.2 has 9 I individual dies and will be hugely inefficient comparatively. Plus it’s a 3 volt led, not 6 or 12 volt.

@sirstinky I think we know one of the reasons they’re running less efficiently: 3V LEDs are just less efficient than 6/12V LEDs, especially as you up the current.

It wouldn’t actually surprise me if that was playing a non-negligeable part into why they’re less efficient.

Yes, as Haukkeli has shared above, the NW Chaos is already bypassed at the factory with a huge metal tab over a metal spring. The topic was on whether his soldering an additional bypass wire improved light output.

What i learnt over so many years of playing with flashlights is that it’s important to verify/check the results on the luxmeter for max output (ceiling bounce is fine, as long as things are kept relatively similarly, esp with similar hotspot sizes between similarly reflectored lights) and also preferably over a duration of time coz that is ultimately what matters.
Also, mainly coz that is very easy and fast to do, even for a flashaholic without much technical skills. :partying_face:

So i think ultimately it is important to verify what it really does in reality on the meter with all factors into the equation, including say first 5, 10 or 20 seconds of turbo (whatever duration the user is interested in running the turbo mode for his specific needs).

Side topic a little :
Anyway, curiousity got the better of me with my JKK76 and this bypass thingy, i am using ~ 10 awg/2.5mm diameter rolled up aluminum foil snaked around the springs as bypass. On top of that, last night i additionally wrapped the whole spring from top to bottom with alu foil externally before inserting the batteries. Did a luxmeter test between bypass and no bypass.
I did not detect any tangible difference in the turbo output, tested first 15 seconds drop.

But of course the reason is probably that the limiting factor is not due to the springs’ resistance, but more like the driver in JKK76 is limiting turbo output to a max of 26-27k lumens thereabouts and the stock beefy springs are more than capable of handling that. The turbo mode is constant current according to the product specs, i read/assumed it was direct drive coz they did put this 直驱 word in the literature, which till today i still do not know what that is referring to. 恒流 = constant current.

ps. since we are on this, do you or bro BlueskyM know what do they mean by the below for the JKK76? It’s been bugging me for quite a while….not sure if i am having a brain block (quite often nowadays) :partying_face:
Just can’t understand in which sense of the light is the direct drive for. Again, 直驱=direct drive, . 恒流 = constant current.

Yea bro, it’s a shame regarding this efficiency aspect. The chinese LEDs are pretty decent in the sheer max output and luminous flux depts, the 2 very important aspects for flashaholics.

I’d not be that concerned if the difference in real life implementations in the flashlight is very small, but from what i found out, it’s not small, though to be fair it’s not insanely huge as well as in not pre 2005 tech of coz. lol! :partying_face:

So just to recheck things in case i made a mistake earlier, I ran the JKK76 and Amutorch DM70 again in 2k lumens levels again last night and verified that both are at the same output levels on the luxmeter (the DM70 is fixed steps and i changed the the JKK76 into ramping mode so that both are at same lvls), 15 mins run duration this time round, the temperature difference between the 2 is rather significant and is not small.
Too bad i gave my IR thermo to my mother in law, if not i’d have temperature figures for a more exact comparison.

Anyway i was reading a Taobao review and found the data below shared by him. Is this data legit and accurate, beats me, but seems to be believable.

Another fella in the reviews section of the Fujian Changda electronics TB listing selling the SFN/SFS/SFH/SFP LEDs also said the efficiency is also lower than Cree.

https://item.taobao.com/item.htm?spm=a21wu.12321156.go-detail.1.40a1f9a1ZdFTLl&id=658331735786

t*6

性价比很高,最大的优点就是便宜,几块钱的p50都可以达到creexhp70的亮度,是我见过最便宜的小面积,大功率led,缺点是光效相对较差。光效为cree的45%–75%左右,毕竟cree在材料和技术上有深厚积累,卖的led也是天价。。需要注意的是即使电压很高,只要电流没达到额定值还是可以一直通过增加电压来增加电流,当电流达到某个值之后,再增加电压,这时电流可以在增加,但亮度不增加,需要自己找最合适的功率。 下面是我测试的数据,可以供大家参考,第一组是cree xhp 70的数据,淘宝200块的手电筒,下面三款都是这家的。测试时,手电筒和led灯都是加上同样的聚光杯,在同样的位置直射向天花板,亮度感应器向上平行放在led位置附近,测的是天花板反射的亮度,因为直接测数据跳动太大,误差太大。已知cree的手电筒极亮时3200流明,可以得到标准流明与测试值的比例大概1比13,再推算出这款led的流明数据。

The fella’s ceiling bounce testing……ice pack, small heatsink
Voltage, current, power, meter raw values, estimated lumens, lumens/watt efficiency

Oh one more thing, i noticed that the table of results posted above for the 国产70 and 国产50 LEDs are not 3V versions. So there must be some more major thing that is in the equation that is accounting for this.
But I guess to be fair, Cree /Luminus has tons more expertise in all areas, in areas like electrical/manufacturing/phosphor etc.

Anyway, as in the Fujian Changda tb link where the chinese fella posted his review/test, they do have 3, 6,9, 12, 27v etc parts for all the different emitters. (of coz for my JKK76 it’s a 3V SFN 55.2)

I’ve been wondering if I should put 50.3 hi’s in place of these SFQ55’s. Warmer temps are available with better cri and at least similar output.

heh heh……if you have the dough, why not. Besides, frankly, sometimes i get a bit scared of all these pocket rockets. Small driver, low mass host for the sheer lumens it is putting out.
Just a few years ago some of us were thinking that things like Emisar is too much of a hotrod. 4-5k lumens in 100g+ host.

This is like double (8k+ per 100g), and we haven’t even accounted for the fact that the input power is even high due to the lower luminous efficiency. :beer:

After playing with the JKK76 at “only” 26-27k lumens and 490g empty, i think it’s enough. Originally i thought with “direct drive” and 30T or Lishen 21700HP 3000mAh, close to 40k was possible. lol!
Nah….i don’t think that is practical at all, not even for short duration 10s turbo burst. It’d be like LEP usage, nearly useless. But of coz there would always be a rare few flashaholics who can appreciate such output/size relationship.

Yeah, these are big numbers for small heap of metal.