/\ . Very well said Lux-Perpetua. … 
Lux-Perpetua - I strongly disagree. Even non-muyggle people (at least some) like to take high-end flashlight on a vacation without any charger. If you don’t want to use usb charging then just don’t. Also I’d not expect any significant cost side effect, as you can have whole usb charging module for just $0.20 (see aliexpress tp4056 usb charging module). Making more models with small differences is not really any benefit from mnf and logistic point of view. Also there is no problem to make usb charging waterproof without rubber flap. Because one way, how to make it, is bad, does not mean it’s always bad.
I also strongly disagree that built-in charging is only for muggles, though I agree that separating muggle and enthusiast lines make sense.
I just extended my previous post to clarify that I prefer to have a charger built-in.
I believe the next step of on-board charging is making USB charging ports waterproof even with the cover open (I can’t remember which flashlight has one of these, I think it’s an Olight?). In that case, yes, please add on-board USB charging. I won’t usually use it but if I need to, it will be there.
Also, I’d want to see more flashlights having better than IPX8 rating (e.g. 10 meters submersible for 6 hours).
Here is a qoute from Freeme who had two of this style battery fail.
From this thread.
Of course some people have not had any problems with built in usb charging batteries like here.
Whether they are reliable or tend to fail might be due to the company that makes them. It’s possible several flashlight brands may be ordering batteries from a single company that makes this style of combo battery. I don’t think anyone knows. We would need to do a lot more research on the failed batteries.
I don’t have time to do all that so I’d rather just buy an OEM battery (Samsung, Panasonic, etc…) or a known good brand and be done with it. It’s cheaper and you know it’s reliable.
I’m not interested in batteries with built in chargers for several reasons (which may have been mentioned above).
-I prefer name-brand batteries with particular performance characteristics. I prefer GA, VTC6 and 30Q cells because they have performed very well for many, many users and are good matches for the lights I buy. I don’t want to use a lesser cell just so I can have the charging capability.
-I would prefer smaller lights and ones that work consistently with unprotected cells. Longer springs that might not perform as well as pills, higher quality springs or pogo pins might have to be used to accommodate a wide variety of cell lengths.
-I think I’d trust a charging system built into a light because they give me the impression that the company might be more willing to put a higher performance system in a light rather than a smaller, possibly more fragile and less sophisticated circuit and hardware into a $5 piece. It’s the reason I perfer LVP in a light rather than in a battery. Maybe I’m misguided, but it makes more sense to me.
I too would like charging systems left out of lights but it appears that they are here to stay. I agree with many of the posts above that one set into the threads and protected from the elements is the way to go. I’ve got six lights with charging systems and only one has a decent rubber cover. One has a metal snap-on charger. The rest are either ok or completely worthless.
I still would like to see some more emphasis on smaller 18650 lights. If Sofirn could design lights in the D4 or FW3A size range, I’d be very willing to buy them over Convoy S2±sized lights. Smaller tailcaps and TIR optics would be nice. They wouldn’t need to be hot rods either (although that might be cool!).
I’d also like to see the SP33 made into a triple or quad optic light. 2000 lumens is very nice for a light this size but I’d like to see something twice as powerful.
it will be a heat sink issue for a small but very powerful light, if light be made with step down or temperature control system, people will complain the short time turbo.
If you add an fan in the light like the PC or laptop, it will be a huge light. I was wondering if there are any other way to help cooling but won’t make the light too big. Liquid cooling?
Bigger shelf
Better fins
More LEDs instead of more power
Better drivers
I’m glad now that I’m reading this thread, otherwise I would have missed Lux-Perpetua putting teacher in a nutshell… 
He did it very well too didn’t he?? . :+1:
In fact let’s run it up the flagpole one more time in case anyone missed it. 
.
I like the looks of many sofirn lights, but I have bought none of them, because of the double-click to get strobe interface.
Double click should get you turbo. Press and hold from off should get you the lowest level. Press and hold from on to change modes.
Double click from turbo to get strobe is OK.
Just my 2c.
Sofirn uses many different interfaces.
You are right… The UI on the c8f 21700 is one I like.
Funny, you are describing the Sofirn SP33 UI exactly, I mean 100% exact. Just got mine today, and maybe even I might not mod this one.
I agree 100% as well - there's a few lights doing this UI now, wish they all did. Too many have clicks to next mode, and hold to turn OFF.
/\ . . I am really liking the SP33 UI too.
Emitters XHP. Compare your Sofirn C8F 18650 (mode group 3 - mode 990Lm) and Sofirn SP33 XHP50 in 1000Lm mode for 30 minutes and you will see a huge difference: Sofirn SP33 XHP50 more compact and much colder.
There are still factors that influence:
Bigger shelf (thick internal integrated emitter shelf)
Many cooling fins
Better drivers
Nobody should be complaining about short run time because it is normal. All small high powered lights have short turbo. If anyone knows of one that has a decent long turbo run time, please let us know so we can analyze how it works.
I am not so pleased by how fast my Astrolux S43S gets hot. It is small with a copper head so you would think it has a decent turbo run time. Unfortunately, it also draws 20A and the emitters and lens are not very efficient. It’s not that bright, yet it heats up super fast.
So small lights need good efficiency (light output to amperage draw), they need a limited amperage draw (nothing crazy high), then they need good control over the temperature (such as calibrated sensors combined with a smooth ramp down). All of this usually results in an expensive light.
I believe Zebralight is known to be really good at building small, yet high powered lights. They are very sophisticated and expensive, which is why I don’t own any.
Liquid cooling is not practical at all. It would be much larger than air cooling. So forget that idea.
I did a search and found your post with pics of this light. Wow that LuckySun F3X looks amazing. I like it alot more than the C8 series with those very functional cooling fins! I wish Sofirn can make one with fins like that and with USB-C recharge!
Love the optional extension tube
In general there are no silver bullets - small but super-bright will be very hot.
1. Liquid cooling - if you add a pump it’s going to work much worse than a fan and adds a lot of complexity as well. Passive liquid cooling, i.e. heat pipes may work, but there’s an easier improvement that I’d suggest trying first:
2. Unibody construction. Improving heat transfer across the light will improve both turbo and sustained performance.
3. For storing heat I suggest trying paraffin wax. It’s lightweight and as it melts it takes away a lot of heat. If you can make a sealed container and good thermal transfer into that container you’ll get much better turbo times.
If you heat 1g of aluminum from 20C to 60C, it can store ~54 Ws of heat.
If you heat 1g of paraffin wax from 20C to 60C, it can store ~360 Ws of heat.
Some lights released recently went with super-thick shelves to improve Turbo times. As you said - that made them large and heavy. I don’t think that using aluminium as heat storage is a good option….but it’s certainly a cheap one.
4. Consider thermally insulating the points where user touches the flashlight body. This way you make the LED hotter and a bit less efficient, so you harm sustained performance. But you can increase body temperature without burning user hands. This improves heat capacity and therefore - turbo times can be longer.
5. Also, I can join others in saying that the more efficient a light is the better. A 1000 lm light that does 50lm/W needs to dissipate or store roughly 17W of heat. A 1000 lm light that does 100 lm/W needs to dissipate or store 7W of heat. Double efficacy again, at 200 lm/W that’s just 2W.
So:
- efficient driver
- buck
- boost
- buck-boost
- many big LEDs (note: this can make the LED a flooder. If you don’t want a pure flooder consider flat LEDs, these are more efficint for throw)
- efficient optics
- multi-layer AR coating is better than single-layer which in turn is way better than uncoated optics
- some multi-layer AR coatings are better than others but they are more expensive as well
- review available reflector coatings - there’s a huge room for improvement though cost may be prohibitive
- TIR+glass lens is a bit less efficient than TIR alone
- some TIR lenses are better than others
- take care about your bezel design, every bezel reduces output but some are better than others
- multi-layer AR coating is better than single-layer which in turn is way better than uncoated optics
- low electrical losses
- quality springs, reasonably fat wires, e-switches…quite easy to do well and overkill doesn’t help much
Note that good cooling improves efficiency as well, but for a regular flashlight this is a small effect. As a practical example please consider Emisar D4 with Nichia 219C and XP-L HI. With the XP-L HI it has significantly longer turbo time even though it’s brighter.
6. I’d like to also add that compact designs are better…if you remove some features that use space you can re-invest that space for better cooling. Same with implementing features in a more compact way. Your light will have the same size and weight but it will perform better. What options to reduce size would I recommend?
- clicky switches are less compact than e-switches
- though quite a few users love the ergonomy of tail switch. Tail e-switch is an option then.
- Zebralight-style light engine
- DQG-style tail caps offer super-low electrical resistance and take less size than the more common spring-equipped ones