OK, thanks, I think I understand the part about general lm/cd tradeoff… and I realize that 3x21C I’m interested in is mainly a big flodder and that throw that it has is just by “lumen brute force”…
…but , specific to different LHP531 CCT’s in your study, you stated:
I understood that as: “4000K and lower CCT LHP531 LEDs are not suitable for throwers.”
So, please correct me if I’m talking rubbish, when I look at your lm/A graph, I look for lm values of 4000K and 5000K LHP531 at 3,5A (3x21C “regulated” turbo of 25A / 7x LHP531) and 7,7A (3x21C FET turbo of 54A / 7x LHP531) and I see they are pretty close:
both cca. 1500 lm at 3,5A
4000K cca. 2800 lm, 5000K cca. 2900 lm at 7,7 A
Since both CCTs have the same LES and there is “just” cca. 100 lm difference on FET turbo I reckon their intensity values would not differ that much (5000K LHP531 3x21C will have cca. 700 lm higher FET turbo than 4000K LHP531 3x21C since 3x21C has 7 emitters).
Therefore I reckon - there must be some other values in your report and/or some of your other emitter related experiences that made you differentiate between 5000K/6500K and lower LHP531 CCTs in your quoted throwing suitability assessment.
…or is it just that warmer CCTs do not make good throwers?
Sorry for the confusion, I just want to understand. Thanks again.
This is usually the case. However, it depends. Certain LEDs can also have a very respectable throw as a warm white variant, especially LED types that inherently have a high luminance at maximum current due to their design. Warm white LEDs (especially those with a minimum CRI of 80 or even 90, as is common with warm white) have a significantly lower efficacy, which affects the luminance, especially when compared to other LEDs with identical LES. An extreme example is the SFT-40 3000 or 6500 K: same light area, but the warm white version has over 80% lower luminance.
In this particular case, the LEDs (except for the PC amber 1800 K) are very similar in terms of efficacy. The difference will hardly be noticeable to the naked eye, so basically every variant except for PC amber is suitable for somewhat decent throwers (with big reflector and very powerful driver of course).
Yes, I should perhaps have made that clearer in the test. However, the rule of thumb “warm = less efficient/lower luminance” still applies. Cold white LEDs therefore have a clear advantage for throwers. In addition, many people say that high color rendering values are not visible in throwers at a distance anyway, or that warm light is irrelevant there, and that cold white is therefore the preferred choice.
Cool white light is easier to spot on an objects far away so it seems brighter but - if the air is not crystal clear
warmer CCTs are actually superior punching through fog and stuff like that.
Which is also why most cars have yellow fog lights (apart from them being close to the ground, so the haze is less blinding for the driver).
I wish we had SFT-40 or similar in 3500-4000K R70. That would be the perfect compromise between still reasonable efficiency and low haze, for throwing in humid air.
5000-6000K just creates a “lasersword” that blinds me more than illuminating anything in an average winter night over here.
R90 is wasted on an outdoor thrower, I need efficiency and brightness in those. Maybe LHP531 or XHP50.3 HI R70 in a large head convoy thrower…
That’s something I wouldn’t answer in such general terms.
Sure, for people who only want maximum range (and nothing else), this may be relevant, because pure performance and efficiency are all that matter.
But throwers can also be lamps with aspherical lenses (Convoy Z1, for example). And in that case, a high CRI LED makes some sense, because such lamps are often deliberately purchased for use at close range, e.g., when camping, in the household, or something similar. Especially nowadays, LEDs with higher luminance and high CRI are available, where this would be worthwhile. Sure, you lose 30-40% of the power, but is that so relevant in everyday life that I would say I want to use blue-tinged light without color rendering?
It’s probably a matter of belief. In any case, I sometimes use the Brinyte ZT40 and wish it had a really good high CRI LED with relatively high luminance.
In the 2mm^2 class there’s the W5050SQ3 3000K, and Kaidomain has yinding glass-style emitters in 4000K low CRI, though it has not been tested. In the 4mm^2 class there’s the new XPL-HI, which apparently doesn’t handle power as well as SFT40.
First of all: Thanks for the (really fast) reviews of the (different CCT) LHP531 @koef3 ! I really appreciate it.
Some interesting details, certainly in terms of the differences in output between the different CCT’s.
As I hoped for (and somewhat expected) they can handle way more than the 10A (drivers) Simon standard bundles them with in his lights. Given the really flat curve in the datasheet (up to 9A I believe), I was already expecting that they should be able to be driven (substantially) harder, before ‘diminishing returns’.
I was just looking at your test of the 4000K XHP70.3 HI, and knowing that Simon drives it really cautiously with a max. 6V/8A driver, that should result in around 5500 lumen (for the 4000K), according to your test.
If you would pair a 5000/6500K LHP531 with the Convoy 3V/20A buck driver, you might be pushing it more towards the upper limit, but that should also push it to above 5000 lumens.
Given that the LHP531 even has a slightly smaller LES than the 70.3 HI, it might be an interesting (more affordable) alternative, based on the current driver options Simon/Convoy currently offers for both LEDs.
(I don’t know if the 6V/8A driver Simon currently offers is easy to mod for a higher output, but I will try to find that out in the future, since that might be something I would like to do on at least one of my lights.)
I was basicly about to finish a M21B with a Convoy ‘12A’ FET driver and a SFQ60 LED, but I might put that on hold for now, just to put in a LHP531 (6500K) and 20A buck driver, just to see how that turns out. (And given that I’ve got those parts in stock anyway.)
If I don’t go for that option, I also have an S21G host in stock, that can perfectly fit both the LED and the driver, so regardless of which option, I’m going to pair them anyway in a light, just to give it a try!
20A in a small host might probably pushing it to hard, but in the worst case I might fry a LED and for how affordable these LED’s are, I’m willing to try it and see what happens!
Also what I hoped for prior to the test, for the same reasons! The LHP531 is indeed a worthy alternative to the XHP70.3HI for all but the highest drive power (where one needs to worry about burning phosphor). It’s a hell lot cheaper for sure, with a better tint and cleaner beam.
I am also very curious about this myself, but for buck drivers. Both his high-current boost and buck drivers are reported to have horribly bright moonlight (I can confirm this for buck drivers), so it would be nice to mod a low-current driver with a good moonlight to output higher power. Unfortunately there are discussions on Reddit of inductors failing from the increased current.
BTW, assuming you have the 6V 8A driver (or any 6V boost driver), how bright is the moonlight? How far do you find the visual spacing is between 0.1% and 1% modes?
I currently don’t have a 6V Convoy driver. I do have a ‘Seeknite L6T’ I recently purchased (very cheap) from Banggood, which is almost a Convoy L6 clone/copy. Unfortunately that driver does underperform substantially, but I might swap in the 6V/8A L6 driver from Convoy, which should be able to fit (nicely) as far as I can tell right now.
I do have 2 M21B’s with XHP70.3 (6V/5A driver) coming in from Banggood, given that they were (so cheap) on sale, that they were almost the price of a M21B host, directly from Convoy. (But with an expensive LED and driver as a bonus.) But I expect those take at least another week to arrive, since Banggood was slow with shipping them out.
But yeah, certainly in that Seeknite L6T flashlight, which is a big(ger) flashlight with quite a lot of mass, I think a 6V 12A driver, or maybe a bit more, should work out quite well! (Pushing it close to/over 7000lm according to Koef3 his test.)
I would very much like to hear about these when they arrive! The 6V 5A driver is actually one that I am specifically interested in, since I wanted to build an S2+ with SFT70 as my EDC. But an EDC should have a decent moonlight, and I want to find out whether the 6V 8A driver has one.
It’s not like Simon and everyone else for that matter wouldn’t like to get more current for an XHP70.3, but its that the MP34XX boost converters max out ~40W. AFAIK the MP34XX are the highest outputting boost converters available for single cell lights.
You’re absolutely right; Simon would not have to offer a higher current driver, because for most of the people the current options will be absolutely fine. Besides that; the gains to be had by a few more amps (combined with lower efficiency and more heat), isn’t worth it for most people.
I didn’t ask/expect Simon to produce a higher amps 6V, I just noted that 6V/8A is the highest power driver that Simon offers. I maybe should’ve frased the “Simon drives it really cautiously” in a different way; maybe "the most powerful driver Simon offers for the XHP70.3 HI is 8A, while the XHP70.3 HI could be driven a bit harder if wanted.
Useful information, thanks!
I will let you know my experience/impression when I recieve them.
One 6V/5A driver will remain in the M21B, but will be paired with a SFT-70 I still had no plan for. The other M21B will keep the XHP70.3 HI, but probably will recieve a 22mm 6V/8A, next time I place an order.
I will probably also swap the original driver in the Seeknite L6T to the Convoy L6 (6V/8A) driver, but that also has to come with a future order.
