[Review] Sofirn SP33 V3 - XHP50.2 3V eSwitch 26650

The Sofirn SP33 has a fairly new update, the V3! Sofirn has kindly asked me to do a review of this light, in exchange for receiving the flashlight. You can find the Sofirn SP33 V3 here on Amazon (non-aff link).


  • Uses a Cree XHP50.2 3V LED with a CCT of 6000K-6500K
  • FET based driver
  • Orange Peel reflector
  • Temperature regulation (no timed stepdowns!)
  • User-selectable stepped and ramping modes

New for Version 3

  • Larger stainless steel bezel
  • Switched from a 6V LED with boost driver to a 3V LED with FET driver (result: brighter, but brightness decreases in proportion to the battery voltage instead of staying constant)
  • Built-in USB-C charging
  • Better UI and temperature regulation

Output - Specs and As-Measured
|Spec. Lumens|1|150|450|1600|3500|3500|
|Meas. Lumens|2|123|444|1708|3800|-|
|Spec Runtime|31 days|26 h 36 m|9 h 21 m|2 h 21 m|1 h 53 m|-|
|Beam distance (m)|3|64|122|187|273|-|
|Peak instensity (cd)|2|1,025|3,775|8,750|18,666|-|

User Interface (UI)

  • Umm, I’m really impressed here. I’m accustomed to every e-switch light having it’s own unique UI (unless its a BLF-inspired light running Anduril or Narsil). And to be honest, I’m usually underwhelmed by the UI. Not with this one! Short of being Anduril, it’s about all I could ask for in a UI.
  • Choice of stepped mode (5 levels including moonlight) and a ramping mode
  • Both mode options are single-click on/off (thank God!)
  • Direct access to low from off (by hold-for-on) (and can then ramp up)
  • Direct access to turbo from off (by double click)
  • From off, electronic lockout with four clicks
  • While in lockout, momentary low mode
  • Has mode memory, but won’t remember turbo. Sometimes I like memory, sometimes I don’t. But since there are shortcuts to both moonlight and turbo, I prefer memory.
  • Strobe mode is accessible via a triple click

Charging & Discharge

  • After completing the runtime test and resting for a while, battery voltage measured a very safe 3.0V. Could be a little bit lower, but I’m not going to complain here.
  • When charging was complete, the battery voltage measured 4.13V
  • When charging, the side indicator LED blinks red
  • When charging is complete, the indicator LED turns solid blue
  • Cannot use USB Power Delivery (USB-PD). This is unfortunate, but also unfortunately all too common. I’m not sure if any of my USB-C enabled flashlights will charge over USB-PD.

Whats in the Box

  • Flashlight
  • Manual
  • Sofirn-branded 5500mAh 26650 battery
  • 18650 adapter sleeve
  • USB-A to USB-C charging cable
  • Instruction manual
  • Lanyard
  • Spare o-rings

This is the first Sofirn light I’ve received with this new box - looks nice!

Convoy S2, Sofirn SC31B, Wurkkos WK30, Sofirn SP33 V3, Convoy C8

Convoy S2, Sofirn SC31B, Wurkkos WK30, Sofirn SP33 V3, Convoy C8

Runtime Graphs
You can tell that they really did finally get rid of the timed stepped down! The adjustments are perhaps a bit too aggressive and it continues to get brighter and dimmer. But overall this is encouraging. IMPORTANT NOTE: this is without any sort of cooling - just sitting on a table with the head stuck in my lumen tube. So in a real-world scenario, it would likely behave better as there would be some air movement.

Thanks for the informative review - the essentials are straight-up given.

I was looking to buying this version and comparing to the V2.

Clearly Sofirn has some work to straighten that throttling. So much ‘yoyo’ effect. This makes the light useless for real use in the field. Can’t imagine illuminating something and the light dipping and then climbing. And then, say about 46ºC thermal kicks in? A bit conservative - people should know by now that a power LED will give off heat. Still catering to the cry babies.

But I’ll give credit where it’s due, their Ui is getting better. The V2’s is great for my intended use; a work light.

I’m still on the fence. In high mode is it more stable?

I will need to run some additional tests and add them in. I’ll probably do a 30 minute High and 30 minute fan-cooled Turbo to see how things compare. I’ll try to get those added soon.

Do keep in mind though, this test was run without cooling and with the head stuck part way into a PVC pipe… this is not the same as real usage.

Mine doesn’t behave like this outside with air circulation

Just looks like the control loop is a little too twitchy. I doubt the temperature sensor is right on the LED’s board or shelf, but probably on the driver board. That lag is the gear equivalent of backlash, a delay. So throttling down seems to do nothing until the (reduced) heat works its way back to the driver. Driver then senses a cooler temp starts cranking it back up, and the delay again skews the readings.

Simple example of a(n oscillatory) control-loop that needs tuning.

The big disvantages of V3 is lack of output regulation. V2 have very good and stable 1000lm regulation, because is used CC boost driver.

I loved that but hated turbo disappearing after the first 4-6 minutes. Models shouldn’t advertise a light at 2500 lumens if it drops out like that. I understand that’s how a boost driver works but it’s still frustrating

The problem is not boost driver but thermal regulation of firmware or missing thermal sensor. For V2 it can withstand longer turbo times, but I think there is time stepdown. Also from gchart review we can see exactly the same V3 have awful thermal regulation. We need V4 with Anduril and very good firmware thermal regulation, they do that with new IF25. I really like 5000K option of V3 compared to V2 cold white.

Anduril has great firmware thermal regulation but I can’t sell it as it’s not user friendly. Sofirn also don’t like it . As a dealer for Sofirn I certainly won’t be encouraging it unless it’s a BLF edition and their own separate version. They did this for their SP36 by releasing 3 versions: SP36 - NarsilM, BLF SP36 - Anduril, SP36S - Simple UI. Too many people were struggling with the first versions so they released their own and I like it the most for selling.

I tested my V2 and it didn’t have timed stepdown, turbo lasted 8 minutes and couldn’t be reactivated due to the cell dropping below 3.7V.

No surprise turbo is much shorter as it’s much brighter. My lumen tube shows 2200 lumens on the V2 and 3420 on the V3 at 30 sec. That quite a bit more for the same host

You right, I have SP36 Narsilm. But if I compared Narsilm vs Anduril, Anduril is more user friendly and easy to adjust. For Narsilm every time I need to read manual. For boost driver of V2 is that the efficiency of driver is lower with low input voltages so it can’t regulate higher output power for longer times compared to 3V version of XHP50. Also I think is possible Sofirn to implement stripped Anduril like in first version of Emisars lights with Ramping OS. You compile Anduril with disabled most of it’s feature. I think for most users ramping UI is preferable over stepped one. So if you are distributor and can just ask from clents which one they’ll like most.

Ordered the V3 kit yesterday off of Amazon on the Sofirn discount, received it this morning. Really like the UI.

Only issues I see is ramping is too slow, and in mode levels, the levels are too few. Moon should be included in the cycle, maybe 1 more. I don't see any issue with 5 levels when they switch that quick.

Wish the 5000K was available on Amazon. The 6500K has the classic blue spill, white center, and yellowish corona.

Also wish they'd blink out the voltage level with that blue switch LED on power up - have it do something useful.

The original "v2" appears to be discontinued though, it uses the XHP50.2 6-volt LED and a boost driver, this model is stated as having "2500" lumens.

The updated "v2" still looks similar physically, but it now uses XHP50.2 3-volt LED and appears to use a similar driver as the SP33v3.0, except a bit lower lumens, this model is now listed as "3000" lumens -- it's basically just a slightly lower SP33v3.0.

beamshots comparing the original SP33v2 "2500" lumens with the updated SP33v2 "3000" lumens and also an SP33v3.0 "3500" lumens

(unfortunately not exactly apple-to-apple comparison since the SP33v2 '3000" lumens I got was 5000k tint while the others are 'cool-white' tint.

I have a couple old SP33's that have the 6V XHP50.2, but unmarked version. Think your V2's were unmarked. Was wondering if mine were V1 or V2. Maybe V1 was an entirely different LED?

Btw, the 3500 lumens rating is pretty honest. Use a 30T or 40T and you get a little better. Bypasses on the springs would probably do even better.

I have one of the 3000 lumen v2 sp33s. I can believe the turbo is 3000 lumens, or close to it. What I find strange are the lower settings. Moonlight was stated as 5 lumens in the manual but it is closer to 0.5 lumens. The low, mid, and high modes, which were supposed to be 150, 400, and 1000, respectively, are more like 80 and 250 and 800. It’s not that noticeable of a difference on high compared to other lights claiming 1000 lumens (Fenix UC30 and PD35). But those lower modes definitely are dimmer than other counterparts stating those numbers. Not that that’s a terrible thing, it just seems odd to have actual output on the lower modes be overstated.

The original SP33 v1 "2500" lumens (XHP50.2 6volt LED) will have a tailcap current of 6 Amps on Turbo, no higher. <= this will be a good identifier for the older SP33.

The SP33 v2 (XHP50.2 "3000" lumens) will have around 8-10 Amps on Turbo (tail current from what I remember, will find my notes...)

The SP33 v3 (XHP50.2 "3500" lumens) will have higher than 10 Amps (probably 12-13+) tailcap current on Turbo, based on my measurements with a fully-charged 26650 battery (UT210E clamp meter) (tail current from what I remember, will find my notes)

Also, using the Zak.Wilson's "CeilingBounce" app and measuring the "ceiling bounce" (sorry I don't have a light integrating device as this time), gives the following graphs, which show different thermal control.

Ah, ok. They were all XHP50.2's. Thanx! I had been planning to swap in 3 channel drivers that CK designed here: https://budgetlightforum.com/t/-/55051, but never got around to it.

I believe these boards will work on all SP33 models, appears nothing changed in the basic driver layout, though not sure, haven't confirmed.

Guys, how do you remove stainless steel bezel of SP33? It will be interesting to be modded with Narsim/Anduril based driver.

Didn't try yet - maybe can try this eve.

It simply unscrews from the body. I used an elastic band on the bezel for better grip.

Pressing the bezel against the sole of a shoe while unscrewing should also work. Takes a little force but will come off.