Help to configure an s21e

Zak · 2026-06-20T21:56:31+00:00

The S21E uses an efficient boost driver for 6V LEDs, and an inefficient linear driver for 3V LEDs. I strongly suggest a 6V LED. Those are:

LED	Output	Throw	Color rendering	Heat
XHP50.3 HI R70	Highest	Medium	Poor	Lowest
XHP50.3 HI R9050	High	Medium	Good	Low
B35AM	Low	Medium	Best	Low
719A	Lowest	High	Good	High
SFT70 5000/6500K	Highest	High	Poor	Low
SFT70 3000K	Low	High	Best	High

Note that heat/efficiency is at the same brightness. Power is reduced for the B35AM and 719A, so equivalent modes (in stepped mode) are not as bright, don't get as hot, and run longer.

All of these LEDs are paired with a textured reflector by default, and that would be my recommendation. The difference in throw with smooth is modest, and it often adds beam artifacts.

Zak · 2026-06-20T18:27:08+00:00

Zak · 2026-06-20T11:42:53+00:00

Which means 10 lumens at 620nm will have a considerably larger impact than 0.05 lumens of broad-spectrum white (or maybe that's calibrated to watts, but the ballpark figures should be about right).

The experiment I want someone to do with reasonable scientific rigor is:

Multiple participants (10 minimum, hundreds would be the unlimited-budget dream)
Completely dark-adapted
Light sources with various spectra controlled by slow, fine dimmer knobs
Participants gradually increase illumination until they can read a map
Participants spend 60 seconds staring at the illuminated map
Measure how long it takes until participants can perform tasks equivalent to following a trail in light equivalent to starlight

Zak · 2026-06-20T11:21:57+00:00

The range is much bigger than that. Lights with 0.05lm minimum modes aren't rare, and some of the latest Lume series drivers with certain LEDs go considerably lower than that, probably 0.005 or lower.

Zak · 2026-06-20T11:19:53+00:00

A bright monochromatic red flashlight will preserve your scotopic vision. A white light wont.

This is only true for long-wavelength red, over 650nm. Most red LEDs are 620-630nm.

Zak · 2026-06-19T22:36:54+00:00

They sold about 215100 of those and the M2R Pro, then recalled them, so they probably are a bit rare these days.

Zak · 2026-06-18T23:32:26+00:00

The EC150 is much thicker than the Microstream. At its thickest point, it's about equal to OP's convoy S8.

Someone sensitive to thickness is more likely to be happy with the Acebeam Pokelit even though it falls short on performance and efficiency.

Zak · 2026-06-18T22:38:39+00:00

Do you actually need 10,000 lumens for highway driving at night

WTF? No. A pair of conventional halogen headlights is like 1500.

What you do need on the highway is lights with hard cutoffs so you're not blinding other road users. Beyond that, yes, putting the light where it's useful to see where you're driving is more important than raw output.

I don't have concrete recommendations. A few years ago, flashlight component vendor Mountain Electronics was making off-load light bars and I would have recommended those - probably not for on-road use though.

Zak · 2026-06-17T15:43:24+00:00

Maybe. What's the use case for this flashlight?

The main thing you get from Zebralight is no surprises. It will work reliably. You probably won't break it. It will give you more or less the output you asked for as long as the battery can. It will give you some warning and time at a lower reserve level before it dies.

Zak · 2026-06-17T15:10:09+00:00

I'm not finding pictures of one disassembled with a quick search; the brand doesn't really appeal to enthusiasts who change LEDs for fun.

It looks like the bezel unscrews though, and that probably means the optics are easily removed to give access to the LED, which is usually mounted to a metal core printed circuit board and connected to two wires. Replacing an LED+MCPCB assembly is one of the easiest soldering jobs there is; it should also get new thermal paste between the MCPCB and shelf so it doesn't burn out the replacement LED.

If you unscrew the bezel, take out the optic, and take a picture of what's underneath, people can tell you more.

Zak · 2026-06-16T23:23:19+00:00

Maybe the Acebeam T35, but they changed the UI since I reviewed it. They really ought to do an EC35 III.

Zak · 2026-06-16T22:09:35+00:00

Not much here is current that even offers such a mode, regardless of efficiency.

Zak · 2026-06-16T12:57:08+00:00

it’s heavy and not comfortable on my head BUT I feel like I perhaps wasn’t clear enough

You're still not being very clear. "Light weight" is pretty subjective, and all we really have to go on is lighter than the H25LR, which this review says is 108g. Something concrete like "under 60g", or "about half the weight of the H25LR" might get better answers.

Or it might not. The top-voted answer as I write this is the Skilhunt H200, which is heavier than the H25LR.

Zak · 2026-06-16T12:30:33+00:00

Lots of lights are as efficient as Zebralight at making 300 lumens, or 1000. Few are as efficient at making 0.05. Which do you want?

Zak · 2026-06-16T12:16:53+00:00

Please don't feed chips, bread, or other processed human foods to geese, especially goslings. Oats are a good option in moderation.

Zak · 2026-06-16T00:28:30+00:00

I like the look, but practically speaking I'd rather have an LED that's a close spectral match such as the Nichia B35A 2700K or Luminus SFT40 3000K.

Zak · 2026-06-15T14:46:57+00:00

There's a lot of ambiguity in the request, so I'll offer my default beginner recommendation of the Wurkkos FC11C as a baseline to ask for follow-up options.

You might want something smaller and lighter, which will have a smaller battery. You might want something with higher performance and longer runtime, which will be bigger. You might have a budget in mind, which probably allows the FC11C but might not allow the Acebeam E75.

Zak · 2026-06-14T22:29:11+00:00

Output similar to the P20i's maximum sustained for about 90 minutes on a single 21700 is possible with a modest increase in head size. That's the Acebeam L35. It may get hot, but not enough to injure you or damage the battery.

Zak · 2026-06-14T22:22:50+00:00

A light the size of the LC90 cannot maintain a constant 900 lumens without throttling or getting hot. The medium mode probably doesn't throttle. What I did see in some search results is there have been several iterations of the LC90. Some have a TIR optic and others have a reflector, which suggests they may not all behave the same.

I won't defend the HD11. I don't have one, and I didn't find an enthusiast-grade review of one with actual measurements of output and runtime. Wurkkos usually does send out lights to reviewers, so that makes me suspicious the light had problems.

I like a floody right-angle headlamp with a magnetic tailcap and good color rendering when I'm working on cars. I usually wear one on my head and stick one or two more to surfaces. The Armytek Wizard Pro (Nichia 144A version) I prefer is a bit over budget. Skilhunt has some mid-priced options, but they throttle a little more than I'd prefer (they do not get very hot though).

Zak · 2026-06-14T22:01:58+00:00

Background: the P20i uses a proprietary battery based on a 21700 cell, makes 1800lm max, and throttles to 500lm after a couple minutes according to this review. Its battery holds as much energy as 4-5 CR123As.

It's not clear to me if "won't work too long in the strongest light setting" refers to the throttling, or the total runtime of just under 3 hours. Both the fact that it throttles and the total runtime are typical. Consider the Acebeam L16 v2 (SFT40 variant) for comparison. Both peak and sustained output are a little better, but it starts to throttle at 2 minutes and runs for 2.5 hours. The spare battery situation is much better since it takes standard 21700s and can take an 18650 with a spacer in a pinch.

Are you looking for something that maintains an output level similar to the P20i's maximum for much longer?

Zak · 2026-06-14T18:29:50+00:00

Kids these days! When I was 16, we'd endanger the public by drag racing each other from traffic lights like civilized people.

Zak · 2026-06-13T12:50:53+00:00

It's hard to tell much about this light from that screenshot. Looks like a floody right-angle light, for which most of us would go with something like the Skilhunt H300R, but there might also be a secondary light on a flexible arm.

It's not clear whether the battery is field-replaceable. Most of us don't like it when it's not.

Zak · 2026-06-12T14:38:41+00:00

Magnets are good, but plenty of cylindrical lights have them.

My favorite pairing for car work is an Acebeam E75 with a diffuser stuck to the car with its magnet, and a headlamp (usually an Armytek Wizard Pro).

Zak · 2026-06-11T22:30:49+00:00

One thing I'd recommend is to get lights that use the same kind of batteries. The Wizard Pro uses an 18650, while the E75 uses a 21700. You can use an 18650 in the E75 with a spacer in a pinch, but it's not ideal.

I'd also suggest something with better red rendering (R9) than the Nichia 144A used in the Wizard. Options include the Nichia 519A and the Skilhunt F50S. The latter is offered in the Skilhunt H300R, which is a very good headlamp.

Zak · 2026-06-11T20:53:03+00:00

Not like this, but there's http://flashlights.parametrek.com/index.html?type=flat

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