Frelux Synergy 2 Review: Following a Precedent


Frelux’s first foray into the flashlight world, the Synergy 1, is something that I would not hesitate to call “very good”. It certainly wasn’t without flaws; however, it effectively redefined the price bracket for custom flashlights. This in tandem with the Synergy 2’s progress I had been following on social media, it wouldn’t be an understatement to say I had high expectations for the Synergy2.

My particular flashlight was purchased with my own money to the tune of $255 shipped. You can purchase the Synergy2 here. I have no conflict of interest with Frelux, and as usual, I’ll be sharing my honest thoughts. So let’s find out if the Synergy2 meets the high bar set by its predecessor, the Synergy1.


Directly from the site:

  • Machined from 6061 USA produced manifold quality aluminum
  • Samsung LH351D 5000k 92 CRI LED
  • Frelux™ multi-chemistry multi-voltage high efficiency constant current driver
  • Frelux™ ramping user interface with memory
  • Physical Reverse Polarity Protection
  • Low Voltage Protection (Both cell types, temporary override capable)
  • Over Temperature Protection (temporary override capable)
  • Adjustable tension, ambidextrous titanium pocket clip
  • Physical button lockout
  • Waterproof (tested to 8ft deep)


95.15mm x 41.7mm (taken by caliper)

163g (with batteries)


I don’t care for presentation very much, and I think Frelux’s is competent; it reminds me a lot of the FW3A’s packaging. And while you don’t get the slick Altoids packaging that came with the Synergy1, this is to be expected given the Synergy2’s size.

Build Quality/Design Analysis

Following in the footsteps of its predecessor, the Synergy2 uses a side-by-side battery configuration which stomps the traditional, stacked 2xAA format. Why is this? Particularly for pocket carry, a traditional 2xAA flashlight tends to inadvertently poke its owner. To this effect, the Synergy2 is intended to be pocket carried, and does not have a lanyard attachment (although I’m sure one can be made) like the Synergy1.

In terms of carrying a traditional, stacked 2xAA versus the Synergy2, I don’t see much difference in ease-of-use, but I do think the stacked format is a bit less natural to hold. For example, one thing I noticed is that I cannot “pistol-grip” the Synergy2 like I can with the Synergy1. This is a direct result of my hand size (for reference, I’m somewhere between small and medium). If you have bigger hands, I’m sure this method is still very much possible. The full bear-grip still comes very naturally, and is further facilitated by notches running down the head.

The same notches that are on the BFG Synergy1 are on the Synergy2.

The integration of the Synergy2’s parts parallels the Synergy1. There is a brass rod that runs down the middle and keeps the three main pieces in place. Changing batteries also still uses the same, rudimentary battery cap that threads onto the brass rod. But a welcome addition is a small, brass nut to keep the main body attached to the head.

No, this is not my photo, and it’s stolen from the product page.

There are two important design elements that stick out to me about the Synergy2:

  1. First is the clip which has adjustable tension. Unfortunately, I do take issue with the clip, and it has nothing to do with the adjustable feature itself. This clip’s lip is angled at 180 degrees, unlike the Synergy1, which makes it quite difficult to clip onto thicker pants (eg. sweatpants). The saving grace here is this one won’t slide out with thinner pants because you can increase the tension to absurd levels.
  2. The second feature is the button lockout. The button – an electronic switch – turns clockwise to lockout, and vice versa to resume function. On the button there are notches running in a circular pattern that help to facilitate this turn. And regarding the electronic switch itself, the feedback is reminiscent of clicking the mousepad on my Apple MacBook: It is clean and quite satisfying.

Despite the issue with the clip I cited, mechanically, both of these features are quite simple, yet there is refinement in this simplicity.

Build quality is also what you would expect for a custom flashlight, that is to say excellent. The surface finish is immaculate and details such as the “Frelux” and “Synergy2” text are clear-cut and easily legible. Synergy1 impressed me with the level of quality it brought to the table, especially for a first-time maker, and the Synergy2 follows suit.

Physical Grade: B+


1-Click (from OFF)Turns on to last used mode.
2-Clicks (from ON or OFF)Defaults to max output.
Press-and-hold (from OFF) Defaults to lowest output.
Press-and-hold (from ON)1) Ramps output up, 2) Ramps output down (second press-and-hold).
1-Click (from ON) Turns off the flashlight.

The Synergy2 uses a ramping interface that is very simple, and it is almost exactly the same as the Anduril firmware in this regard. But there are no disco, strobe, or hidden modes to speak of. For me, the Anduril firmware, while no doubt filled to the brim with features, fell short because of its complexity: That is to say, the UI sheet gave me an aneurysm every time I looked at it. Conversely, I’d posit that even most “flashlight muggles” can pick up and figure out the Synergy2’s interface in a couple minutes.

Output/Runtime/Beam Quality

The Synergy2 comes with a Samsung LH351D LED by default – yay! Hi-CRI and plenty of output. The beam itself is decent. I would have liked a smoother transition between the hotspot and the rest of the beam; but of course, this doesn’t matter much in practical use, and it’s a perfectly acceptable beam by most standards.

White wall at a couple feet. Taken with my iPhone X and with no editing.

Now here’s where things get interesting. The Synergy2 has a very large voltage range, and you can use anything from a single AA rechargeable battery to 2x14500s (of course, don’t mix battery types) to power the flashlight. The parallel circuit begetting this wide voltage range, in my opinion, sets the Synergy2 apart from the competition.

That said, there is a certain wild-west nature to runtimes between battery types, and it took multiple tests between Benjamin (the head of Frelux) and myself to confirm this. In fact, I initially thought I had a faulty driver when testing with standard Eneloops, and so a second sample was sent out.

You can see in my graphs that with standard Eneloops the Synergy2 abruptly terminates around the two hour mark. This was a far cry from the near three hours that Benjamin got with Eneloop Pros which also dimmed in output near the end. Eventually, though, we concluded that the Eneloop Pros are able to sustain a higher voltage in tandem with more capacity which accounts for the standard Eneloops simply cutting off. While I haven’t tested Eneloop Pro myself, I have watched a time-lapse that confirms the runtime with Eneloop Pro. I also fully intend to do a runtime test myself once I get my hands on some Eneloop Pro.

Parasitic drain from OFF: 2.7uA
About 75 years to drain (2) Vapcell 14500 batteries. Consider it negligible.
Battery Runtime
Duracell Alkaline AA1 hr
Eneloop AA (2100mAh)2 hr
Eneloop Pro AA (2350mAh)~ 3 hr
Vapcell 14500 (1000mAh)2.5 hr
Terminated at 1.35v for Duracell Alkaline.

There are voltage cut-offs (LVP) built-in at both 1.35v for Alkaline and at 0.8v for rechargeable Ni-Mh. You will note that there is a spike in my runtime graph for the Alkaline in my second sample. The flashlight actually cut out here due to heat – the driver has temperature protection – because I was running back-to-back runtime tests. I believe the standard Eneloops, however, cut out because they simply cannot sustain the voltage draw of the flashlight any longer.

Clearly, like with most other AA flashlights, you should not run standard Alkaline batteries with the Synergy2. There are a myriad advantages – including cost of ownership and environmental impact – to running rechargeable Eneloop batteries, and performance is but one of them. But if you want max runtime I’d go with Eneloop Pros, and if you want max output I’d go with Vapcell 14500.

Technical Performance Grade: A-

The Subjective Take

Overall, the Synergy2 gets a lot of things right and is good…startlingly good. Like, to the point where even as a critic I struggle to point things out that are objectively “bad”. You guys know that I don’t hesitate to tear apart the stuff I review, to the point of which some have called me “harsh” and “unfair”. And they’re not strictly wrong, so let’s get more subjective: I think the biggest flaws about this light are ones that are inherent to the design, and that’s the size and weight. I touched upon this earlier when I cited that I was unable to pistol-grip this flashlight like with the Synergy1.

To elaborate, the side-by-side (SxS) format works a lot better with AAA batteries, particularly for pocket carry, and that’s just a fact. A SxS AAA flashlight fits a lot easier in a pocket than a traditional 2xAAA flashlight, but these returns diminish when you move up to SxS AA because while a AAA is only slightly shorter than an AA battery, a AAA is significantly thinner. The respective dimensions of the Synergy1 and Synergy2 illustrate this very clearly.

If you’re someone like me who carries a front-pocket wallet, I found that the Synergy2 significantly impeded my ability to pull out my wallet. And furthermore, I work a part-time job on the weekends that involves a lot of squatting up and down. The Synergy2, due to its gargantuan size, is far from ideal in this regard, and I could feel it digging into my leg. Every. Single. Time. For reference, I mostly wear jeans.

Weight comparison to some other EDC flashlights:

Frelux Synergy2163 grams
HDS Rotary (with clip)112 grams
Lumintop/BLF FW3A 98 grams
Oveready BOSS 35 89 grams
Frelux Synergy187 grams
Okluma DC181 grams
Surefire Stiletto 78 grams

You might say – “But you’re comparing apples and oranges. The Synergy2 is running two cells, and all these other flashlights are only running one”. And you’d be right. It’s not a fair comparison, but it’s going to be made nonetheless because these flashlights all fall into the same category: They are EDC flashlights.

OK, so neither the size nor the weight is ideal. Are there any other potential deal breakers? Yeah, there’s a couple like the lack of moonlight and the hassle swapping batteries. But personally, I think the biggest hurdle will be the price. These concerns aside, the Synergy2 has in spades everything that the ideal EDC flashlight should have. More than anything though, the Synergy2 perfectly captures the spirit of the Synergy1 and takes it to the next level.

To this end, Frelux’s design ethos can be described as straightforward and simple, yet with a touch of sophistication. Ever been stuck on a math problem where you think it’s impossibly complex? Then when you see the answer, it’s ridiculously simple? Yeah, this is what Frelux is good at doing. Just because the answer is simple, though, doesn’t mean that it doesn’t take work to derive it. So while neither what the Synergy1 nor the Synergy2 is doing is game changing, both combine a lot of the elements that more mature flashlight collectors will appreciate.

Just to be clear: This certainly isn’t the flashlight to buy if you’re into toys, that is to say lumen cannons and flashlights with a dozen blinky modes. You won’t be satisfied with what the Synergy2 delivers. The Synergy2 is geared towards more utilitarian users who want something that is simple in function, yet has a touch of elegance. Hence, I’d argue that the target audience here will be people who have been in the hobby longer and know exactly what they want out of a flashlight.

Cumulative Grade: B+ ★

You can click “VIEW MORE” to understand the thought process that goes behind my ranking.

My ranking list takes into account four factors: Intended use-case, overall design, price, and how this all plays into actual use. I do this so as to null the common, functional disparity between custom/high-end flashlights and budget flashlights. This really is a catch-all method, so the usual disclaimers apply: This is my list, it’s subjective, and you don’t have to agree with it. So on and so forth.

The Synergy2 loses points on the letter grade because of its size and clip. And after subsequent re-evaluation, I have found some more flaws. The lack of moonlight is disappointing, and swapping batteries is far from convenient.

Now I’m sure some people will question why I have placed the Synergy2 below the Synergy1 in terms of my value system, the stars. After all, isn’t the Synergy2 significantly more advanced than its predecessor? The problem here is that the Synergy1 is an anomaly not unlike the MBI HF was. You can purchase original versions of the Synergy1 for $100 shipped which is an absurd value for both the quality and the unique design you are getting.

The Synergy2 undermines most custom flashlights which start at $300+ for an aluminum model. And it effectively beats them out not only in terms of value, but also overall function. My rankings reflect this. So naturally, at the $250 price point for an EDC flashlight, the Synergy2’s only competitors are the HDS Rotary and Executive. HDS also smacks most custom flashlights on every level, and they are my gatekeepers for the B+ and A- range.

The HDS Rotary sits at B+ simply because it lacks a decent clip; this is why I have awarded it ★★★ (Revolutionary) despite its lower grade. On the basis of UI, build, and design it edges out the Synergy2 and is the better value (despite being an extra $30) if you can sacrifice the lack of a clip. Once you factor in the price of a decent holster, though, I can see it going both ways.

It’s not as much of a wash versus the HDS Executive though. Yes, the HDS Executive has more functions overall, but it also lacks the unique design that the Synergy2 has. Personally, I would still buy the Executive if I could only have one, but some will gravitate towards the Synergy2 because it has greater output and the design is slicker.

So nonetheless, while very solid in design and execution, $250 is pushing it when you compare it to the HDS flashlights. Not a fair comparison, I know, and everything is relative – yada, yada. Still, while I wouldn’t go so far as to say that the Synergy2 redefines the price bracket like Synergy1 did, I will tentatively award it a star as being “worth it”.

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