S2+ emitter recommendations

LED Flashlights – General Info 18650 Flashlights
1

Hi BLF! New member here.

I’m considering buying a few Convoy S2+ for backup lighting (indoor ceiling-bounce) and would appreciate emitter recommendations and other info. Efficiency is most important. High CRI isn’t critical, 80+ should be fine. Flood vs throw not important but prefer neither extreme. Any temp 4000K-6000K is fine but again, I prefer efficiency in this case.

These could be used by young family members so LVP and temp control is important. High lumens not important as 200-500 will almost always be enough.

So what’s the middle-of-the-road S2+ I’m looking for? And could I get a discount if I bought several (4-6) ?

Thank you.

2

Hello JagerLion, welcome to BLF!

I believe you’ll like the Nichia 219C a lot on an S2+ with smooth reflector. It strikes an excellent “concentrated but not pinpoint” beam pattern, the tint is right in the band you’re requesting, and Nichia is not quite a powerhouse, so with 7135×4 driver config, it’ll hit your mark.

I have an SST20 one that I really enjoy but wouldn’t recommend to you, it’s way too throwy.

3

Thanks, Jack. If I understand you, I’m looking at this:

https://www.aliexpress.com/item/32962537117.html

Nichia 219C at 4000-5700K w/ 7135x4 driver. 1400mA should provide continuous 500 lumens. yeah? That would be more then enough for my needs.

4

I have a Nichia-equipped S2+ and it is a solid performer.

That said, my favorite is a XPL HI with an orange peel reflector. Pretty good throw with a more diffused hot spot

It’s wonderful to have so many choices and to have such a moddable platform. It just makes it hard to choose at times…

5

Neither luminous efficacy or efficiency (efficiency is weighed efficacy) is so important. If you think it is, get a green emitter (example) and enjoy. Spectral power distribution accuracy matters, though, at least if you want things to look how they look under sunlight or blackbody radiator light.

Here is the LED section at the Convoy flashlight store.

The LH351D emitter is a popular choice now and available in CRI90 spec, its die size is similar to that of XP-L or XM-L emitters so it is in the same league throw wise, nice for indoor use.

CCT/temperature wise you ideally need to choose something around 6500K to get that additional efficiency you aim for:

I usually prefer to choose warmer CCTs so not my cup of tea, but its your choice.

What hurts the math energy efficiency wise is having to go with linear drivers, which burn excess voltage and power as heat. A buck driver is a better choice, but options are limited in this regard and too are gains also with certain questionable driver choices. So won't say anything else.

6

Thanks, Barkuti.

If I read your chart correctly, a 4000K emitter will have 55% efficacy vs a 6500K emitter will have 95% efficacy? That seems quite an extreme difference to me and not considering CRI. For strictly efficiency, would that translate into ~ 2x runtime for a given lumen level? What S2+ emitter would you choose?

7

That chart is for blackbody radiators, not proportional with LEDs.

8

As BurningPlayd0h says the above table is for blackbody radiators. The actual figures for leds are very different because they put most of their energy into visible spectrum, this means the difference between 4000K and 6500K in leds is a lot smaller.

Asking me what S2+ emitter would I choose? My preferences are quite a bit different, JagerLion. I do not really care much about efficiency as it is a magnitude weighed by the luminosity function, and I dislike the fact that the large ignorance in these subjects has delayed a lot the development of led blackbody radiator accurate light sources. To me, along with photographers and film-makers, light source quality is absolutely paramount.

What I most care about is about comfort and rendering accuracy. Given that I also in some way support the findings of Arie Andries Kruithof, as a rule I prefer lower CCT with lower illuminance levels. This the reason my bedroom light is 3000K high CRI led, and I also use a cozy 2700K 25W tungsten bulb powered lamp (I have a bag full :-) of them).

If you really need to extract the most of your energy, I'd try to find the most efficient buck driver. The LD-29 is really good, unfortunately it is Ø20mm so not suitable for the S2+. The problem basically is that you are asking for something most don't fully care about, which is maximum wall plug efficiency or maximum electrical to optical power efficiency. And in this respect an efficient driver is very important.

This AA / li-ion driver looks like a nicely designed boost / buck driver, uses an R050 sense resistor which at 2A drops 0.1V, this is my guess about its maximum driving current as it is meant to be fed with Ni-MHs and at that level of power to the led the input current from a Ni-MH is already at 6-7A. However this is all guesswork and the plain lack of any kind of information is disturbing.

Then there's this 2.5A buck driver “theoretically” meant for red leds. But it is a buck driver, and so it will work equally well with any standard emitter, regulating for as long as the input voltage is high enough. The wrong thing about it as I see, is the piss poor sense resistor setup with a combined 0.1Ω resistance, this means a whopping 0.25V of drop when 2.5A go through the sense resistor stack, i.e. a lot of loss which shouldn't be there when sense voltage could just be 0.05V, for example. In other words, its efficiency could be better and also its regulation time and window are lower just because of its unnecessarily high sense voltage.

If you still insist in asking me about what emitter would I choose… wellp, remember I am not you. I myself would likely lean to something between 2700K and 4000K. Maybe in your particular case I'd probably try a 5000K CRI90 LH351D (F2R2S2 so 5000K leaning low), but I am saying this just because I am trying to put myself in your shoes. 5700K CRI90 LH351D is also available (it is V2Q1S2 and its CCT is 5700K leaning high, the ad title has a typo -it's not V2Q2S1-), but that's already very far away off my preferences.

9

The 219C 5700k is an underrated option if you want a cool(ish) tint and high-CRI. I’ve been using that and the 2700k SST-20 S2+ for some of my recent photography (instagram link in my signature).

10

Lh351d high cri option is also available. I have one on order with the OP lense for more flood

11

Out of all these, which one would provide more flood out of the box (without the use of TIR lens)

- LH351D

- SST20

  • Nichia 219c

XPL-HI and XM-L2 are out of the question, coz I already have S2+ with those two LEDs. :person_facepalming: :zipper_mouth_face:

12

ok, I’ve managed to test the following S2+ variations with orange peel reflectors (requested Simon to change from SMO to OP):

old XML2 T6-4C 4300-4500K (7135*4)
SST20 4000K (7135*4)
LH351D 4000K (5A)

Out of the box, the SST20 is more of a thrower than flooder. Gotten a TIR 45, which made the SST20 behave better closeup. However, when all’s said and done, I’d have been better off getting the LH351D to begin with.

The TIR 45 was purchased from here. It’s designed for XML2 LED size. Although the SST20 is smaller, it works.
Ebay link to TIR

13

Here’s a picture of the LH351D4000K 5 amp with orange peel reflector
Beam shot indoor 4000k s2+ Lh351d 4000k s2+ - Album on Imgur

14

the XPL in 3200k is a really nice option too, I have a couple of lights with these in and they`re great, the tint is towards the rosey side. They don`t cost a lot either! :slight_smile:
here`s one.