[Review, now with working images] Sofirn SP40 headlamp (right angled 18650/18350)

Note: images are missing at the moment as I have an issue with my blog. Hopefully they'll be back soon.

Update: images are back!

This light was sent to me by Sofirn in exchange for doing a review, without any requirement to give a positive rating. Thanks to Sofirn for providing the light.

There's already lots of reviews of the SP40 on BLF from last year but hopefully another one can't hurt and may give some new insight.

This review originally appeared on https://davestechreviews.wordpress.com/2020/07/10/sofirn-sp40-headlamp-review/


About the light

The Sofrin SP40 is an angled headlamp that runs of an 18650 cell. You can also run it from a shorter 18350 cell.

Quick review

The Sofrin SP40 is a great entry level headlamp that has the quality of lights twice its price. It’s a great all rounder, coming with USB charging, an included cell, head strap and even an extra body tube for shorter cells.

I’d recommend it if you’re after a mid-range headlamp and want something better than something that runs off AAA batteries.


The Sofirn SP40 headlamp is available on Amazon UK (£36) and Amazon US ($33).

Sofirn SP40 specs

Sofirn list the following specs for the SP40

Maximum lumens 1200 lm
Impact resistance 1m
Water resistance IPX7 (1m of water for 30min)
Weight 2.3oz / 65g (I measured it at 66g)
Throw 136m
Dimensions 108mm by 25mm (I measured it at 111.3mm 27.4mm at the head and 24.1mm at the tail)
Sofirn SP40 specs

The physical light

What’s in the box, manual

The SP40 comes in a cardboard box with bubble wrap. Sofirn have printed card and plastic boxes too, so I was surprised to see something so plain.

Why do I keep taking photos of cardboard boxes?

As always, what’s in the box is more interesting. Sofirn provide a cornucopia of accessories and parts with the SC40 package.

  • SP40 headlamp
  • an 18650 cell (inside the light)
  • short tube, to fit shorter 18350 cells
  • Micro USB cable
  • 2 spare O-rings
  • Steel clip
  • Headband
  • Manual

Appearance and quality

The SP40 is black anodised aluminium. The anodising appears fairly thick and doesn’t seem to get scratched by the clip.

The threads are rectangular cut and the tail cap fits perfectly. You’d expect this machining from a light twice the price.

The cell tube has springs at each end, so should be able to handle a range of cell sizes. The springs are strong but not being a high current light they’re not especially thick. The light doesn’t flicker when you shake it, so they’re doing their job fine.

Tail end, with a magnet

Physical design, size

The Sofirn SP40 is a long 18650 light by default but because it comes with a short tube for a 18350, it’s almost 2 lights in 1. 18650 and 18350 cells are about 65mm and 35mm respectively.

Short Long
Cell 18350 not included 18650 included
Length 81mm 111mm
Weight (without cell) 57g 67g
Weight (with cell) 81g 115g
Cell mAh I used a 1200mAh Keeppower Sofirn’s is 3000mAh.
Up to 3400mAh available
18650 vs 18350 Emisar D4, Sofirn SP40 in 18650 mode, Sofirn SC31B Emisar D4, Sofirn SP40 in 18350 mode, Sofirn SC31B

The 18350 tube that comes with the SP40 works with Sofirn’s SC31B too.

Sofirn SC31B is now tiny

Head strap

Although it works fine as a pocket light, Sofirn sell the SP40 as a headlamp. The head strap it comes with is fairly heavy duty, including a top bit and handles the weight of the SP40 in 18650 mode fine.

SP40 in the head strap, with the clip too

The head strap accommodates the SP40 in 18350 mode fine too. When in 18350 mode then it’s noticeably lighter.

SP30 in 18350 mode

Magnetic tail

The Sofirn SP40 comes with a magnetic tail cap. I haven’t tried removing it but it may be possible. The magnet is fairy strong and holds the light on a screw in both 18650 and 18350 modes.

The magnet easily holding the SP40 in 18350 mod

As the magnet is in the tailcap, you can unscrew the body from the head and wonder where the cell has gone.

Took me a moment to realise the cell was in the tube

Pocket clip

The steel pocket clip clips on to the 18650 tube either way round (unlike on the Sofirn SP31B). As the tube is reversible anyway, this doesn’t make much difference.

SP40 (left) and SC31B (right) with very similar and interchangeable body tubes

It’s not a deep carry clip at all, so whichever way round you have it, it’ll stick out of your pocket quite a bit.

The clip is very strong and takes effort to take off, so there’s little risk of losing the light when it’s clipped to something.

The clip fits on the 18350 tube too, slightly off centre on the tube, so you can rotate the tube and adjust it a few mm.

It’s too long when pointing down though, so won’t clip to a pocket.

There’s no lanyard supplied with the SP40 but the clip has a hole you could attach one to.

The SP40 is almost light enough to use as a hat light, though being a headlamp it points down instead big forward.

You can kind of point it forwards on a hat but this it won’t be secure enough to walk with. Best to use the provided headband.

Interface, switch

  • Click on
  • Click off
  • Hold to change brightness
  • Double click for turbo

Changing brightness goes low, medium, high, then back to low. The light will remember your last mode (even if you don’t).

You can also do 4 clicks to lock / unlock the light. The anodising on the threads mean you can physically lock it with a quarter turn of the tail cap too.

The user interface passes the intuitive test, as the switch turns it on and off. This means you can hand the SP40 to someone and assume they’ll be OK with it.

There’s only 3 modes and turbo here. No strobe (hooray!) and no moonlight (boo!).

The SP40 also has an indicating light on the switch. This comes on for a few seconds when you turn the light on:

  • Green – over 30%
  • Red – under 30%
  • Flashing red – very low

Charging and cell

You can charge the SP40 with the supplied micro USB cable – either the included 18650 one or any other 18650 or 18350. The indicator light on the switch goes from red to green to show it’s charged.

Charging at around 1A

You can also turn the light on low when it’s charging, or even without the cell it body tube in place. This means you can use the SP40 as a USB powered light.

The included cell is rated 3000mAh. This is pretty good, though high end cells are up to 3400mAh. With a single XP-L emitter, even turbo will only pull a few amps, so most cells will work with this.

Light output


Mode Lumens Runtime
Low 5 220h
Mid 90 15h
High 450 4h 10min
Turbo 1200 1h 50min
SP40 modes


The SP40 holds turbo for a few minutes before stepping down to roughly the high level.

You can see the output continues to drop beyond 450lm. This happens on high too, as the cell voltage drops. Sofirn have used a fairly basic driver in the SP40 that doesn’t regulate the output. The SP40’s driver is good quality but very basic. This isn’t noticeable when you’re using it as it drops so slowly.

As with most lights with a turbo mode, the output drops down from turbo (either thermally throttled or on a timer). With more expensive lights that use a regulated driver, the output will then stay constant. I expected the SP40’s driver to be regulated, based on the very high quality of the light in general. It’s was a bit of a let down to see it drop. In reality though, the SP40 only drops about 10% in an hour, which isn’t even noticeable.

Sofirn could have spent more on a driver in the SP40 but that would have put the price up for consumers too.

Low Voltage Protection

After almost 6 hours the low voltage protection kicked in and the light turned off. This is where a driver will turn off just before the voltage gets to the point that it could damage the cell. The SP40’s cell measured about 3.3V at this point. Cheap lights don’t include LVP and can damage cells if you’re not careful, so it’s good to see Sofirn have included this. The battery check in the SP40 indicator light means you get a warning when the voltage gets low anyway.

LED and Beam

Orange peel reflector and LED

Here’s the SP40 next to my 4000K D4 and cold white SC31B. The D4 has a TIR optic, which smooths the hotspot out. The SP40 has an orange peel reflector, so still throws a bit for its size but has a more even beam. It’s not mentioned in the manual but I expect the SP40 has a CREE XP-L LED. The SC31B’s smooth reflector gives a much more defined hotspot and spill. The orange peel reflector looks like a good choice for the headlamp.

The SP40 is colder white (higher Kelvin) than my D4 but isn’t as cool as the SC31B or some of my other lights. I haven’t seen details on the emitter Sofirn use but I expect it to be around 5500K.

4000K XP-L HI Emisar D4, XP-L Sofirn SP40, Sofirn SC31B

The driver on the SP40 is unregulated and uses PWM (turning on and off quickly) to make different modes. On very cheap lights, the PWM can be very noticeable and annoying on low modes. Not so with the SP40 though. I could see the PWM on low and medium modes with my camera but not with a naked eye. My camera couldn’t detect it on high but I’d expect that to use PWM too.

PWM only noticeable with a camera


Some other budget right angle 18650 headlamps:

  1. Astrolux HL01 (runs Anduril, moonlight mode, comes with 18350 tube too)
  2. Wowtac A2S (neutral white option, 0.3 lumen mode)
  3. Skilhunt H03
  4. Lumintop HL3A (2800lm turbo, moonlight mode, runs Anduril)
  5. Convoy H1 (lots of LED options)

On the higher end, Zebralight and Armytek are the go to brands and give you lots of choices.



  • High quality machining
  • Comes with cell, USB charging, head strap, 18350 tube, magnet, clip, kitchen sink
  • Price


Some of these are a bit picky and would only be expected on a light twice the price. Still, hopefully Sofirn’s next headlamp will get even more things right.

  • Output falls with cell voltage
  • No moonlight mode or shortcut to low
  • Colour temperature is a bit high for my liking
  • Pocket clip could be deep carry


The Sofirn SP40 is great value for money and makes a great first headlamp. The quality is exceptional and you get loads of accessories for the price. The driver is the only thing that’s lacking slightly but it wouldn’t put me off recommending it.

Did your WP review get taken down?

D’oh. Yeah, looks like WordPress suspended my blog and now all the images have gone here too. Hopefully I’ll get it back soon.

I was wondering where the pics were.

Thanks for the review. I was about doing another one, but I think there’s not much left to tell.

Just one thing: I got the NW model from Sofirn (colour temperature not specified) and was surprised to see a green beam. Last time I saw that was the light from Olights R50. I mean, that’s ok. Looks nice outside. But it’s far away from BBL. Am I the only one who got a SP40 with this extreme tint?

The Amazon listing didn’t say whether this was the NW one but mine is warmer than I expected, so I think it could be. It’s noticeably green by itself to me, even on a white wall. Comparing it to other lights though, it is slightly on the green side of the BBL, though not extreme at all. Is there a good way to measure this with a phone?

Always interesting to see people’s thoughts on lights.

The sooner the XPL versions are gone and LH351D are used instead, the better.

And a <1lm moonlight mode.

And stabilisation.

Regulation would be nice too, yep.

But for the price, it’s hard to ask for too much.

The images came back. Hopefully the captions make more sense now!

Just fyi, driver is removable with no damage. It's glued around the rim and at the top of the vertical PCB, it's soldered to the switch PCB. Key is to first de-solder the top, then de-solder the LED wires, then gently tap down on the top of the vertical PCB to break the glue seal.

Switch PCB showing soldered ends of the vertical PCB:

Used solder wick to remove the solder joints:

Solder removed, now there's nothing holding the switch PCB down:

Used a 20 mm FET+1 driver, so now the SP40 is running Anduril2 with a 351D 2700K

Impressive work and nice LED choice. I wish I had the skills to mod lights like this. Maybe I should start practicing.

Why do I always feel like this when Tom posts a mod:

You mean you unsoldered the switch board, then just happened to have a new driver that would fit the switch board having Anduril 2, and then put it all back together? Or did you just upload Anduril 2 to the existing driver?

Yea, sort of 1/2 the mod was shown . Didn't get a chance to upload the pics of the rest of the mod.

Think in this case, you are close to correct. I had a 20 mm driver sitting around already reflowed with the FET+1 parts, ATTiny85, etc. Then downloaded the latest Anduril2 I got, wired it up, pretty simple mod actually.

I get the bare (bare is better ) driver PCB's from OSHPark, reflow the parts myself. In this case, I lose the charging.

One more thing -- I reused the stock switch PCB, just ran 3 wires from the new driver up to the top of the light: ground, switch wire, and wire for the AUX LED's running through the 2 holes and soldered to the matching pads (grnd, switch, AUX LED's). The AUX LED wire also has a resistor on the driver to knock down the voltage/amps to drive the AUX LED's. Only the RED AUX LED's light up because of the lower Vf of RED.

I do this sort of stuff so many times over the years, forget sometimes mentioning the obvious things, least obvious to me

Thanks for the comments. The thing that is getting me is the right angle board needed to hold the switch PCB. Did you design in pads so you could solder the right angle board to the new driver? Guess that’s easy enough if you are making a whole new driver. Or is that not needed at all? Really nice work.

Ohh - no, the right angle board (i.e. vertical board) is not needed. The switch PCB sits on a shelf, then when the rubber cover is put on, and switch bezel screwed down, it's held tightly in place. I'm using the 2 holes in the switch PCB to pass the wires through.

Uploaded the pics of the full SP40 mod, posted in gchart's review thread here: https://budgetlightforum.com/t/-/56981/98

Probably still left out a couple things - should have shown the soldered in-place switch MCPCB... :FACEPALM:

Thanks Tom! Seeing full teardowns makes me a lot more confident when I eventually try to mod a light.

Thanks Tom. That’s an incredible mod!

I’m considering this headlamp and have a battery question. Will this light also take cr123 batteries, 1 or 2, depending on which tube you use?