Review: Astrolux S41s (Quad Nichia 219, 18650/18350)

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Review: Astrolux S41s (Quad Nichia 219, 18650/18350)

Multi LED lights were once a thing you could only pretty much get in custom lights, but over the past two years there have been a few that have made it to production. Today I have the Astrolux S41s that uses 4 Nichia LED’s and is made from stainless steel and copper. Thanks to Banggood sending this to me to review. I have a link to where you can pick it up in the description below.

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This light is made from polished stainless steel and a non polished copper pill that houses the driver and emitters. The copper does appear to have a coating on it to prevent tarnishing. The stainless steel resists scratching decently well but it does scratch.

Due to the steel and copper used in this light it’s got some heft to it. With battery I measured it at 168.7 Grams. By comparison the Emisar D4 with the short tube and the same battery weight in at 76.5 grams. Length with the short tube is 80mm and the width at the widest is 27mm and the narrowest 22.4mm. Due to the tail cap button this light is longer then the Emisar D4 with either configuration (Long or short tube).

The knurling on this light is super aggressive. It’s the most aggressive of any of the lights I own. While I like that in hand, it makes for a terrible pocket EDC as it will tear up your pockets quickly I would think. With this stainless steel model you could sand the knurling down a bit with sandpaper to smooth it out some more. Threads came dry on this light which is a bit odd. Threads themselves were normal, smooth and fine. I will be putting on some conductive grease myself probably Ford XG-12.

This is a tail switch light and the cover is semi transparent but there isn’t an LED under the tail cap by default unfortunately. This is good for overall battery life but lessens the cool factor. The light will tail stand especially in the short configuration but it’s only sitting on material about 50% of the way around, it’s not the most stable design.

This light is also compatible with an 18650 tube that’s sold separately. I choose the rainbow model vs the black so that it would go better with the stainless steel of the S41s. Knurling on this one is also deep and aggressive. Since 18650 batteries have a greater energy density it will increase the runtime as well. The included deep carry clip fits on both tubes and is a pretty good slim deep carry clip.

This light uses 4 Nichia 219C LEDs in a neutral white around 5000k. On mine here the led’s are definitely on the warm side for Nichia 219C’s. I don’t mind this at all and prefer it to cool white. Output is listed on max output of somewhere near 1600 lumens. Everything is powered by a FET driver, so a high drain battery is needed for optimal performance and output. The downside is heat, especially with the Nichia LED’s which typically run hot.

The Astrolux S41s has a very floody beam. The Carclo type optic smooths the beam out pretty well. At shorter distances there is a bit of a flower petal effect on the beam but I don’t actually notice this in real world use.

Parasitic Drain was measured at 4.1uA which is pretty low. Working voltage is 2.8 to 4.25v.

I did my runtimes with an Aspire 18350 1100mAh battery and the short tube. The light does step down from 100% output after a few minutes, and I believe this is timed. Over the next 17 or so minutes the light continues to slowly decline as the battery is emptying out. It had a hard step down and then went into moonlight mode after 25 minutes. At this 25 minute mark I took a temperature reading of 125F on the body of the light, which is uncomfortable to hold. To improve this runtime dramatically you can purchase separately the 18650 tube and be able to draw more current from the FET driver allowing for more performance, lumens, heat and runtime.

This light uses the UI that Toykeeper developed for the BLF A6. By default the light ships in Group 1 which includes 7 modes from Moon to Turbo and it can be changed by short presses. This is quite a few modes but they are evenly spaced. Group 2 includes 4 modes, low, medium, high, turbo that are accessible via short half second presses. If you press longer (0.5 seconds to 1.5 seconds) you get into a different group of moon, turbo, tactical strobe, battery check, and a bike flasher. The light does have memory modes and moonlight which is both nice.

The firmware is a little complex but Toykeeper has a great writeup on all it’s features. Instead of me reading that too you I will have a link in the description to where you can read more about it.

Death by Heat
This light gets hot, so hot in fact it can cause itself to fall apart. I had a ceiling fixture in my bedroom fail catastrophically while testing this light so I used it on full power with the long tube and a Sony VTC6 to bounce light off my ceiling as a light source while dressing in the mornings until parts to fix my ceiling light arrived. When I went to shut off the flashlight it was incredibly hot. I quickly shut if off the light and dropped it at first because it was so hot. I picked it up with my sleeve and took the battery out to get the battery out. I measured the battery with a non contact thermometer at 165F and the light at about 155F (It had cooled down a bit). This is dangerously hot, not only for humans but also uncomfortably hot for the battery.

You might be thinking ok it got hot but all is well now right? Not quite, the combination of the heat and me dropping the light from the heat caused one of the wires to come loose on the driver board and caused the mosfet to shift on the pad an no longer make contact. I ended up taking the light apart and and taking it to a friend to use his hot air solder station to remove the mosfet and resolder it. After that the light works again just fine. So if your running the light and it gets super hot don’t drop it.

Is a brown Astrolux box that fairly sturdy. Inside is foam for the light, a pocket clip, lanyard and extra tail cap cover. Only the 18350 tube ships with this light. You can optionally purchase an 18650 tube if you would like that flexibility. They are available in black, rainbox or silver. Also the S41 is available in aluminum if you want, it’s lighter.


  • Very affordable for a quad LED light with 3 tint options available.
  • Stainless steel is a very small price premium.
  • Space efficient design considering it’s a tail switch.


  • This is a heavy light for its size. The normal S41 trades the stainless steel for aluminium which would save a bit of weight.
  • Knurling is aggressive and may rip up pockets easily.
  • Really HOT, and the thermal controls are minimal, it dos have a decent amount of mass to spread it out though.
  • Not as bright as the Emisar D4 but still plenty bright for most use cases.

When the Astrolux S41 came out it was only the affordable quad production LED lights on the market. However the Emisar D4 came out and was super popular in 2017. Costs are pretty comparable depending on where you shop from. For me I like the ramping UI of the D4 better, it’s lighter and shorter but it a little more expensive.

The S41 I think is a more attractive light, and has that tail switch, lanyard mounting holes, and a smaller diameter head. It has a more traditional flashlight UI that can be complex if you want it to be but it doesn’t have to be. While both lights are similar they are unique enough you could easily have both. I like that the S41 is available with a couple of different LED choices because everyone has their own preference in LED’s. I am glad Nichia 219C’s are an option. I like that the accessories are pretty cheap too with the long body tube being very affordable.

If your interested in picking up a Astrolux S41s you can get one on Banggood. If you don’t have a small Quad LED hotrod flashlight in your life, get one now, they are a lot of fun!

Last seen: 2 months 4 weeks ago
Joined: 10/01/2012 - 18:45
Posts: 476
Location: NE

So currently with coupon you can get this light with short (18350) tube anodized finish for $25. it is much lighter and makes a great edc. great light for the buck! I think i am up to three of them now. Smile