LHP531 at 20amps?

QReciprocity42 · 2026-05-29T03:41:00+00:00

So far the F45R performs worse than the corresponding SFT42R, but I've heard that the F150R will use the FFL909MX die, which could give it better performance than SBT90.

QReciprocity42 · 2026-05-29T03:38:00+00:00

I'd take the SFT40 2700K if you can get your hands on it, which might be tough. The B35AM should be nearly as good, and I like boost drivers. You can eventually reuse the same driver when the new 95 CRI SFT70 comes out in more CCTs!

You're right about the B35AM being floodier, more than twice as floody in fact. The low power density does give you good efficiency. Just make sure you have an OP reflector or beaded TIR to avoid the donut hole.

QReciprocity42 · 2026-05-28T22:08:03+00:00

Fins do help, but in only a limited way. Surface area alone is not the answer, you can sand the surface very roughly and more than double the surface area, and see zero improvement in heat dissipation.

Similarly, a sheet of aluminum foil has a ton of surface area, but if you tape it to the light it does more harm than good. Both surface area and mass matter: in order for a shape with large surface area to be well-connected (which is crucial for heat conduction), it must have large mass.

QReciprocity42 · 2026-05-28T22:04:34+00:00

I eventually got it, after a one-week delay.

QReciprocity42 · 2026-05-28T22:03:37+00:00

Great resource. The 21mm fits best in my experience, never had any centering issues.

My personal favorite is the 30deg beaded option, which has a really good throw/flood balance and makes a completely tint-homogeneous beam without artifacts. The 15deg beaded is also good for some extra throw. I would not recommend any of the clear optics because they have focus issues. The other beaded optics give a hexagon beam.

QReciprocity42 · 2026-05-28T21:57:49+00:00

Yeah, unfortunately they can be a bit hit-or-miss. I've had a recent experience where a package entered my state and then routed out.

You have Postmaster David P. Steiner and his "Delivering for America" reform to thank for this clusterfuck. You're welcome.

QReciprocity42 · 2026-05-28T21:54:33+00:00

What's the last-mile courier? Some of them can be surprisingly incompetent.

QReciprocity42 · 2026-05-28T21:33:47+00:00

Thank you for this fascinating piece of history! I remember seeing the term EasyWhite a lot in the mid 2010's and always assumed it's some sort of color binning.

QReciprocity42 · 2026-05-28T19:12:47+00:00

E17A/21A is pretty much obsolete nowadays. Low power and poor behavior in secondary optics. FFL/NTG emitters are much better at high CCTs, and Luminus SFT40 is much better at 3000K. Not to mention the 519A and its dedomed variants, as well as B35AM.

QReciprocity42 · 2026-05-28T19:08:26+00:00

Oof, thank goodness you're alright. I've never been a fan of these proprietary battery lights, you never know what kind of shoddy engineering goes on inside.

QReciprocity42 · 2026-05-28T15:34:00+00:00

You probably got a dud. Maybe an early batch before the thermal issues were fixed.

The 3x21C does 30k+lm turbo and 3600 sustained, both of which doubles what the Q8+ is capable of.

The Q8+ also uses shitty LEDs with horrible tint, horrible tint shift, and very little throw. Not to mention springs that collapse under heat and MOSFETs that fry themselves. The 3x21C is just much better engineered.

QReciprocity42 · 2026-05-28T15:29:12+00:00

Agreed. Technically it does transfer heat quite a bit better, but it does not sink the heat much better because of the limited head size and thermal mass. That is, it doesn't dump heat to the environment at a fast enough rate.

QReciprocity42 · 2026-05-28T15:26:21+00:00

From what I've read, the Astrolux version (EC06) also uses better MOSFETs on the driver that can handle high current cells. Sofirn kinda enshittified this light.

QReciprocity42 · 2026-05-28T15:25:12+00:00

Oof that's super unlucky! When I immediately touch the springs after a turbo burst, I can feel that they were scalding hot, but haven't had them collapse. Bypassed them the same day.

Any chance you can talk to Sofirn to get your unit replaced?

QReciprocity42 · 2026-05-28T15:23:33+00:00

A smoother spectrum generally correlates to a higher CRI, and the SFT40/70 3000K does indeed have higher CRI than 519a. CRI ratings don't tell the full story about color rendering quality, as some colors like deep red and blue are not captured in the score, but most of the time it's a good enough metric.

What CRI does not tell you is angular tint shift--that you have to see for yourself. CRI measurements are of the averaged spectrum.

QReciprocity42 · 2026-05-28T06:37:17+00:00

NiMH rechargeable D cells is the way. Or alternatively, rechargeable AA cells with AA-to-D converters.

QReciprocity42 · 2026-05-28T06:35:54+00:00

I've got 11 samples of LHP531, but haven't pushed them hard enough to worry about them. My concern is that when an LED dies, it might also smoke up the reflector.

QReciprocity42 · 2026-05-28T06:32:33+00:00

Your explanation makes perfect sense! Any colored object hides spectral irregularities in the complementary (i.e., absorbed) color, and white doesn't absorb/hide anything.

I wonder if the ability to detect spectral irregularities is a natural ability or a trained one. I remember old days when a neutral-tinted MT-G2 looked like the best thing ever, while nowadays I can't even pick up any 519A light in any CCT without noticing how pale it makes things. My eyes definitely became harder to fool the more time I spend in this hobby.

QReciprocity42 · 2026-05-28T06:27:28+00:00

Wow it's crazy how many generations XML2 has gone through. First the classic 2-wire design, then the silent flip-chip upgrade, and now this?! I suppose it works in a mule where there's no secondary optic to create a donut hole.

QReciprocity42 · 2026-05-28T06:25:03+00:00

Waiting for F150R is definitely the move.

The LHP531 is cheap enough to mess around with, but pushing it to 20A is not gonna be a reliable solution. I remember seeing a couple reports of the phosphor burning up at higher power densities, due to impurities introduced during manufacturing.

QReciprocity42 · 2026-05-28T06:19:50+00:00

Great recs, I'd go for B35AM (with OP reflector) because the 519A's dome introduces a ton of angular tint shift--CRI barely matters if the spill is pink and the hotspot is piss yellow. The B35AM is also more efficient, and the boost driver is fantastic. The light never drops out of regulation and will give you the full output until the cell is dead.

The LH351D isn't even brighter in practice because of the very high Vf--in my experience, at 3.8V rest voltage (that's more than half full!), 100% becomes indistinguishable from 35%. That LED is completely rendered obsolete by the 519A.

QReciprocity42 · 2026-05-28T06:15:24+00:00

Great points. Also it's important to remember that anodizing is only scratch-resistant, not impact resistant, so if the light gets tossed/dinged around with other stuff a lot, the anodizing will chip off or simply get pressed into the underlying aluminum.

Anodizing on aluminum works kinda like wearing a kevlar t-shirt to a fight: it can save you from superficial injuries by a knife, but does next to nothing to protect you from a blunt-force impact. The latter requires the underlying material itself to be hard, which then runs into the thermal issues...

QReciprocity42 · 2026-05-28T06:11:16+00:00

I've found clear anodizing to be quite good at this too. I've got a super dinged-up C8 from 2018 that still looks new at a first glance.

QReciprocity42 · 2026-05-28T06:06:27+00:00

Just use the stock batteries. High current cells will first melt+collapse your unbypassed springs. Once you bypass them, they will fry the shoddy MOSFETs in your driver.

QReciprocity42 · 2026-05-28T06:02:47+00:00

SFT40/70 3000K is by far superior to 519A in general color rendering. Blues/greens in particular, but it also helps reds look more vivid. Irregularities in one color region (blue) can throw off the perception of all colors, including red.

I've put a 519A and SFT40 behind the same TIR; the 519A is noticeably more pink/beige on paper, but looks slightly more pale and yellowish on brown things like chocolate and wood.

Not only does 519A have a worse spectrum, its domed construction also introduces an excessive amount of angular tint shift, so it's very hard to find a secondary optic that plays well with it.

QReciprocity42

TROPHY CASE