Fireflies PL47g2 2021 Review – A Great Headlamp for Nerds


The Boring Stuff

Reddit user u/melr1818 kindly lent me this light for review. Here is the official product page where these go for $50 and I think that’s a perfectly reasonable price. Below are the official specs.

What comes in the box?

The box isn’t particularly fancy nor particularly basic. It’s a black cardboard box with a foam insert to hold the light secure. The following items are included in the box:

  • The light itself
  • Headband
  • 3 spare o-rings
  • Pocket clip
  • Anduril UI chart

Size & Measurements

From left to right:
Fireflies E07x Pro
Skilhunt H04 RC
Fireflies PL47g2
Emisar D4V2
Noctigon KR1

MeasurementMeasured (mm)
Bezel Diameter27.0
Head Width28.0
Head Depth40.8
Head Height31.0
Switch Diameter10.5
Switch Proudness~0.8
Body Tube Diameter (internal) 21.9
Body Tube Diameter (maximum)24.7
Body Tube Length75.6
Pocket Cip Slot Width5.0
Pocket Clip Slot Diameter23.1
Tailcap Diameter (maximum)28.0
Tailcap Length15.5
Driver Diameter<23.7

Weight with Headband & Samsung 40T: 188g / 6.63oz
Weight with Samsung 40T: 150g / 5.29oz
Weight empty: 80g / 2.82oz

User Interface

I wish PL47g2 came with Anduril 2, but it comes with the next best thing: Anduril 1. I’m not even remotely prepare to do a full UI table, so here are some of my favorite features:

  • Customizable mode memory
  • Shortcuts to moonlight & high
  • Customizable brightness levels
  • One click on/off, hold to change brightness
  • Battery voltage readout
  • Candle mode
  • Muggle mode (for handing to normal people who aren’t flashlight nerds)

Anduril 2 has some meaningful improvements over Anduril 1 that I did miss while using PL47g2. Fireflies already includes it on some of their other models, so I’m disapointed they didn’t update PL47g2 with Anduril 2 when they released this 2021 version. With that said, I think it’s possible to update it. More on that in the driver section.

Modes, Brightness & Throw

Disclaimer: Lumen measurements were taken on a Texas Ace 3.5″ Lumen Tube. CD measurements were taken with a Digital Illuminance HS1010A (the meter included with the Texas Ace Lumen Tube). Runtime tests were performed with the Ceilingbounce app on my smartphone. All of these tests were performed with a fully charged Samsung 40T battery unless otherwise specified.

Emitters: This particular sample has Nichia 219B SW45K’s. Fireflies advertises 2500lm turbo output from these, which isn’t what I measured, but you won’t miss that extra 500 lumens. You don’t choose 219B’s for their brightness anyway.

Level Lumens (@ Turn-On)Candela (@ Turn-On)Throw (meters)
Turbo (150)19907000167
High (113)7202532101
Medium (75)18264051
Low (37)227718
Moonlight (1)TLTLTL

TL: too low to measure

Runtime & Currents

Turbo (150): starts out just under 2000 lumens and drops very quickly down to ~180 lumens at 45 seconds. It stays right around there until the 320 minute mark when low voltage stepdowns kick in. It ran for awhile after that but I stopped the test once it reached a moonlight level, because Anduril will last for AGES at a moonlight level.

High (113): looks similar to turbo, but starts out a little lower and has some fluctuation during the first few minutes of runtime. It lasts a solid 40 minutes longer than turbo as well. That really shows just how much power is eaten up by those few seconds of nearly 2000 lumens when Turbo is activated.

Medium (75): A flat 180 lumens until 375 minutes when low voltage stepdowns start.

Max Regulated* (65): I think this is the top of regulation, so I did an extra runtime test here. It’s a flat 118 lumens until 585 minutes when low voltage stepdowns start. Updated info in the Driver & Regulation section.

LVP: Anduril has both a low voltage warning and low voltage protection. When the cell gets low, the light will start dropping brightness in big noticeable steps. When it gets low enough, the light will turn itself off (including most of the aux LED’s).

Current: I’m not equipped to do extreme duration runtime tests or extremely high current measurements. I only measure the currents on low modes and I calculate the estimated runtime of those modes based on the capacity of the battery or batteries I’m using for testing.

LevelCurrent @ Tailcap (milliamps)Estimated Runtime
Low9343 hours
Moonlight2.084 days
Standby (aux high)1.608104 days
Standby (aux low)0.1303.5 years
Standby (aux “off”)0.0984.7 years

Driver & Regulation

I can’t find any good information on what sort of driver PL47g2 is using. It doesn’t appear to be one of Fireflies’s awesome Lume1 drivers. It might be a basic 7135+FET driver but I’m not totally sure. There are flashing pads visible, and I believe it’s possible to update the firmware with an Emisar/Noctigon flashing kit.

Update: Reddit user OKflashlightaholic confirmed for me that it’s possible to reflash these with Anduril 2, and has given me reason to believe this not a 1×7135+FET driver, but a 4*7135+FET driver.

Regulation is nothing to write home about, but it’s a little better than anticipated. Turbo (150) and High (113) drift downward with battery voltage. Medium (75) and Low (37) are consistent across the battery’s voltage range though.

On most Anduril lights with 7135+FET drivers, regulation stops at level 65. Here, level 75 is demonstrating good regulation so I may be incorrect in my assessment of the driver. 7135+FET is just my best guess.

Emitter & Beam

Fireflies offers several emitter options for this light at the time of writing:

  • Luminus SST20 5000K
  • Nichia 219B 4500K (shown here)
  • Luminus SST20 4000K
  • Cree XPL-HI Cool White
  • Cree XPL-HI 4000K

The owner of this light chose the Nichia 219B’s and they’re delightful. They’re definitely below BBL (lean toward magenta rather than red) and look great. They produce a lot of heat though. When bouncing the light around in my white photo booth, I measured CCT at 3900k and RA (CRI) at 97 with my Opple Light Master 3 while the light was on its highest brightness setting.

The beam is floody and artifact-free, as you would expect from a quad frosted optic like this. It’s perfect for a headlamp. It still provides a decent amount of distance though, especially on Turbo.

Turbo is pretty insane outdoors. Even with these 219B’s that can’t handle a ton of current, it still gets wildly bright. I find my ~500 lumen H04 RC impressive on turbo outdoors. This is another level, but it only lasts for a few seconds. The sustained output of ~180lm is plenty bright for most tasks. I actually found myself using the low mode (level 37) a little more frequently while I was on a camping trip because medium (level 75) seemed too bright.

Moonlight & Tint Comparison from left to right:
Fireflies PL47g2
Fireflies E07x Pro
Emisar D4V2
Skilhunt H04 RC

Moonlight is nice and dim. It’s well below 1 lumen, but it’s too low for me to get a precise measurement. It’s not much brighter than the aux LED’s on high.

The aux LED’s are pretty bright, brighter than those of any others I have on-hand. Above is a Fireflies E07x Pro, Fireflies PL47g2, EMisar D4V2, and Noctigon K9.3. They are cyan only, not RGB. That’s a bit of a shame but I suspect that’s part of what keeps the cost down. They look beautiful, but I found high mode to be too bright and low mode to be too dim. Anduril desperately needs a medium aux brightness setting.

Design & Construction

PL47g2 looks a little funky. It’s got a huge head that sticks out to the side. Fireflies did that to make the light quite a bit shorter than it would have been otherwise, so it’s not without reason. It still looks weird though and makes it less pocket friendly.

Build quality is great. I find no faults. The anodizing is thick, even, and matte. The threads are smooth, anodized, square cut, and well lubricated. The o-rings feel a little too stiff though and it takes quite a bit of force to twist the threaded sections together as a result. If they wear out prematurely, three replacements are included in the package.


I have mixed feelings about the switch. It’s tactile and audibly clicky, with a short travel distance. It’s plenty accessible and it’s backlit too. Those are all good things.

What I don’t like is the location and the implementation of the backlighting. Since the switch is on the top of the head instead of the end, it’s really un-natural to press when mounted in the headband. You have to squeeze the whole light from tail to button. A switch on the side like some other manufacturers use is much better for head-mounted use.

There are four LED’s under the switch. Two of them are controlled in Anduril and can be set to the normal aux LED modes (off-low-blinking-high), but the other two are on all the time, nomatter what. There’s no reason for these not to be controlled in the firmware too. It also means the only way to make sure your headlamp is completely off and invisible is to use mechanical lockout, which is quite difficult to do while it’s mounted in the headband.

Carry & Ergonomics

Pl47g2 is not great in-hand or in-pocket. Holding it in what I’m calling a “pistol grip” leaves most of my fingers feeling cramped, and there’s nowhere for my pinky to go. In a full hand grip, the head isn’t pointed in a direction that’s natural for use. If I use it handheld, I try and hold it so that my index finger is on the button and the tailcap is in my palm.

The big lopsided head and sad pocket clip make PL47g2 difficult to carry. The clip is basic and feels like an afterthought. It’s pretty shallow carry. I would not choose this as an EDC light.

I did find during my testing that a Sofirn SP35 clip fits really well. It’s the same clip that’s included on Sofirn IF25A, IF22A, Wurkkos TS21, and HD20. Below is the stock clip on the left, and the SP35 clip on the right. A big improvement!

PL47g2 works best mounted to a headband or magneted to a surface. The magnet is not the strongest I’ve seen, but it’ll hold the light up on a vertical surface. With the floody, high CRI beam it’s a delight to use as a magnetic work light.

The headband isn’t great but it didn’t prevent me from using it. It’s a 2-strap headband with a rubber piece in the front to hold the light. Both straps are adjustable, but I had to adjust them as large as they would go for it to be comfortable. The light slips into two rubber loops on the front that hold it in place. It’s a less than elegant solution. I wish Fireflies had included something like Skilhunt HB3 which has a detachable top strap, and uses a clip to hold the light. For what it’s worth, I was able to squeeze PL47g2 into my HB3, but just barely.

The lanyard is… pretty terrible. It’s just some paracord crudely melted together, with a swivel hook and a plastic button added. It’s cheap and it sticks out like a sore thumb in an otherwise high quality package.

Batteries & Charging

PL47g2 takes one, unprotected, flat top, 21700 battery. I did all my testing with a Samsung 40T that you can get with the light from fireflies. I also tried a few other cells. An unprotected flat top Molicel P42A worked great. An unprotected flat top Samsung 30Q worked, but it rattled and would shut off if I jostled the light enough. A protected button top 18650 worked just fine, but using Turbo would probably trip the protection circuit for most cells. I don’t think button top or protected 21700’s will fit.

No charging solution is included with PL47g2.

What’s the deal with fireflies?

Fireflies seems to be plagued with problems. They’ve had quality control & customer service snafu’s going back a couple of years. My E07x Pro came with tail threads so bad that the tailcap got stuck halfway unscrewed! They’re sometimes impossible to get a hold of if you do have an issue. It took me two months to get replacement parts.

If you order from Fireflies, make sure to pay with Paypal. Most users don’t have problems, but if you do get burned, you can open a dispute via Paypal and get your money back without too much hassle.

Recently they’ve also been having issues getting parts for their fancier drivers. This light was supposed to be a PL47g3 with a nice Lume1 buck driver and USB-C recharging built in, but the worldwide electronics parts shortage put a stop to that. I believe Fireflies released this 2021 edition (and E07 2021 edition) with cheaper drivers just so they will have product to sell while they wait for a more reliable Lume1 driver parts supply chain. That’s not their fault, but it’s disappointing nonetheless.

If you buy PL47g2, it’s possible that a significantly improved PL47g3 is only a few months away. It’s also possible it’ll never be released. Just take that into consideration when buying.


Here are some lights in the same class and how they compare. This is not an exhaustive list by any means, just a few similar lights that I find compelling.

Update: Hank from Emisar/Noctigon has announced that he’s making a right angle version of his popular D4V2 model called DW4. It will have RGB aux LED’s and much better driver options (including dual-channel & boost).

Lumintop HL3A: Smaller, lighter, 18650 battery instead of 21700, one less LED, newer firmware (Anduril 2), marginally better clip, no aux LED’s, (probably) better driver, not quite as good LED options, similar price point

Skilhunt H04 RC: Smaller, lighter, 18650 battery instead of 21700, one emitter, better switch location, worse (but still good) user interface, better pocket clip, no aux LED’s, best-in-class headband, wide cell support (18650, 16650, 18350, 16340, CR123A), better driver, magnetic recharging, more expensive. I consider this one the best overall headlamp on the market.

Armytek Wizard C2 Pro Max: More expensive, more durable, more efficient and better regulated driver, more typical shape, fewer emitter options, wider beam, magnetic USB recharging, better headband, worse UI, better button placement, no aux LED’s, same 21700 battery, better pocket clip, bike mount included

Wurkkos HD20: Same 21700 battery, bigger and heavier, similar headband, better pocket clip, separate flood and throw channels, USB-C recharging, powerbank functionality, less expensive, worse UI


I think there are better headlamp options out there for most people (Skilhunt H04 RC), but if you’re a nerd like me, you love Anduril, 21700’s, Aux LED’s and Nichia 219B’s, and you don’t mind taking a chance with Fireflies, this light can’t be beat and I highly recommend giving it a try.

Thanks to u/melr1818 for lending me this light for review!

3 thoughts on “Fireflies PL47g2 2021 Review – A Great Headlamp for Nerds

  1. outstanding review format and details, great info.. it shows you put a lot of time in. Thanks for the Opple data too.. very helpful


  2. Interesting review. Is the magnet in the tail cap removable? Magnets mess with my compass so I tend to avoid them for outdoor gear. Thanks for any info.


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