# Olight SR51 (XM-L, 6xCR123A/RCR 2x18650) Review: RUNTIMES, BEAMSHOTS, VIDEO and more!



## selfbuilt (Sep 14, 2011)

*Warning: pic heavy, as usual. *










The SR51 is the latest member of the "small" class of SR-series lights from Olight. Unlike the SR90/91/92, the SR50/51 use standard batteries. In this case, you have the choice between 6x CR123A/RCR (with the standard carrier) or 2x 18650 (optional carrier).

*Manufacturer's Specifications:*

LED: CREE XM-L U2 bin
Max 900 lumens (OTF), 700 meters long throw.
Battery: 6x CR123A or optional 2x 18650
Optional Battery Bracket: CR123A batteries are standard, but optional 18650 bracket
Working voltage: 4.5~8.4V
High mode : 900 lumens /110 minutes
Low mode: 250 lumens / 10 hours
Strobe: 10 HZ 
Anti reverse battery polarity protection
Two digitally controlled constant brightness levels and strobe, friendly user interface (press and hold the switch for transferring modes).
Access to strobe instantly
Excellent heat dissipation ability
Highly water resistant to IPX-8
Reflector: Mini Orange peel reflector
Lens: Strong anti reflex coating lens, 99% effective transmission
Head: Stainless Steel Bezel
Material: Aluminum Alloy body, Mil-spec: MIL-STD-810F
Anti-scratching type III hard anodization, Black
Engineered anti-slip knurling for grip
Dimension: D 63mm (2.48in) x L 190mm(7.48in), Weight: 400g
Accessories: Includes one strap, one charger, one operator’s manual, one O-ring
MSRP: ~$140










Packaging is high-end on the Olight SR-series lights. Inside the presentation carry case (with metal hinges and closing clasps) you will find the light, diffuser cap, wrist lanyard, belt-pouch, extra o-rings and manual – all securely packaged in cut-out foam.










From left to right: AW Protected 18650, Olight SR51, 4Sevens S18, Sunwayman M60R, 4Sevens X10.





From left to right: AW Protected 18650, 4Sevens S18, Olight SR51, Olight SR92, Olight SR90.

All dimensions are given with no batteries installed:

*Olight SR51*: Weight: 405g (505g with 6xCR123A), Length: 190mm, Width (bezel) 62.0mm
*4Sevens S18*: Weight: 700g (800g with 6xCR123A), Length: 233mm, Width (bezel) 63.0mm
*4Sevens X10*: Weight: 156.9g (245.7g with 1x26650), Length: 135.5mm, Width (bezel): 46.0mm
*Eagletac M3C4 XM-L*: Weight: 348.0g, Length: 164mm, Width: 61mm (bezel)
*Sunwayman M60R*: Weight: 262.0g, Length: 163mm, Width (bezel) 57.2mm 

The overall weight of the SR51 is in keeping with its size (i.e. substantial, but not overly hefty). It is definitely toward the larger end of 2x18650 or 6xCR123A XM-L lights, but not as large as the SST90-based 4Sevens S18.


































The styling of the SR51 is in keeping with the high-output SR-series lights, but without the built-in battery pack. Ridge detail is fairly high on the handle, so grip is good. Anodizing is a matte black, no chips on my sample (manufacturer claims hard anodized = type III). Lettering is sharp and clear, in bright white against the dark black gloss background. 

Screw threads are square-cut and anodized at the head, to allow for lock-out. :thumbsup: 

The standard battery tube is reminiscent of the 4Sevens S18, but is removable here (there are also a few less contact points on the head). It fit 6x CR123A or RCR comfortably (but firmly). Note the carrier is mainly made of plastic. Given the parallel channel arrangement, you should be able to run the light with only 4x or 2x cells - but I wouldn't attempt this on anything other than Lo.

The optional 2x18650 tube holds two batteries, side-by-side. Design seems substantial, but also has all-plastic end-pieces.

_*NEW:* Normally at this point in the review, I like to show the beamshots. But I’m trying something new - video reviews showing both the basic build and user interface. Beamshots will follow after the user interface and circuit discussion._



Videos were recorded in 720p HD, but YouTube defaults to 360p. Once the video is running, you can click on the 360p icon in the lower right-hand corner, and select the higher 480p or 720p options, or even run full-screen. 

*User Interface*

The SR51 has the same straightforward interface as the SR90/91/92 - press and release the blue button to turn on. Press and release again to turn off. :kiss:

While on, press and hold the button for 1 sec to switch between the Lo and Hi output states. The light has mode memory, and retains the last output setting for when you turn it back on.

To activate the “hidden” full-power strobe mode, do a quick double-press while on. 
Repeat to switch back to constant output modes. 

*PWM/Strobe*






Strobe on the SR51 is a typical fast "tactical" strobe at 9.6 Hz. This is the same as the early SR92 I recently reviewed.

There is no sign of PWM on Lo, I believe the SR51 is current-controlled. 

*Beamshots:*

And now the part you’ve all been waiting for. 









The SR51 uses a Cree XM-L emitter (well centered on my sample, with a masking disc around it). Reflector is a medium orange peel (textured reflector). Given that the reflector is fairly deep, I would expect throw to be pretty good.

The overall dimensions look very reminiscent to the 4Sevens S18 – in fact, the bundled SR51 diffuser cover will also fit over the S18 bezel. 

And now the white-wall beamshots.  All lights are on max output, on their typical battery configuration (6xCR123A for the SR51). Lights are about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance on the camera, to minimize tint differences. 





























































The SR51 has a well-defined center hotspot, with a wide spillbeam. Overall effect is very similar to the Eagletac M3C4 XM-L.

I have now done 100-yard outdoor beamshots, in the style of my earlier 100-yard round-up reviews:






Output is clearly in a different class than the SR90 and SR92.











Again, overall beam profile looks a lot like the M3C4 XM-L. 

*Testing Method:* 

All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.

I have recently devised a method for converting my lightbox relative output values (ROV) to estimated Lumens. See my How to convert Selfbuilt's Lighbox values to Lumens thread for more info.

*Throw/Output Summary Chart:*

*Effective November 2010, I have revised my summary tables to match with the current ANSI FL-1 standard for flashlight testing. Please see http://www.sliderule.ca/FL1.htm for a description of the terms used in these tables.*






No surprises here - the SR51 is again very comparable to the Eagletac M3C4. Output and throw are very respectable for this class of light.

*Output/Runtime Comparison:*










Interesting take-home message here – the 6xCR123A SR51 is a pretty close comparable to the 26650-based 4Sevens X10 in output and runtime. Of course, it is also a much larger light with greater throw.




























Overall output and runtime is excellent for the class - consistent with a current-controlled light at these levels. 

Runtime on 2x18650 is similar to other recent lights on that battery arrangement. 

On 6xCR123A, you typically get even longer runtime that 2x18650 (of course, that depends on specific battery capacity). Regulation remains excellent on primary cells. 

6xRCR shows good performance (for the lower capacity of RCR).

*Potential Issues*

Light is larger than most lights in this output class (especially if running on 2x18650).

Holster is serviceable, if a bit basic.

No real Lo mode (i.e. still above 200 lumens on Lo).

*Preliminary Observations*

The SR51 is something of an intermediate Search and Rescue-style light. Not as high output as the SR90-92 class lights, it still packs a pretty good punch for its size. And it has the advantage that it can run on all possible configurations of standard batteries – 6x CR123A/RCR or 2x18650. For that matter, you could probably get by with 4x or 2x CR123A/RCR configurations (though only on Lo).

Styling is similar to the other Olight SR-series lights, and gives the light a substantial feel. True, it is larger than most lights of this class, but that's mainly to accommodate the good size reflector (for decent throw) and the 6x CR123A/RCR arrangement. 

Comparing it to the 4Sevens line (with which it shares some common ancestry), the SR51 is intermediate in size between the X10 and S18 Maelstrom-series lights. Output is clearly closer to the X10 class – but with a prettier beam and greater throw. 

Performance is excellent on both output levels and on all battery types tested - great regulation and runtime across the board. :thumbsup:

Olight has also chosen to keep the interface the same among the SR-series lights, so you always know what you are going to get. I think the solid implementation of the two-modes (with a hidden strobe) continues to be a positive for the keep-it-simple crowd. :kiss:

Of course, given its size, this light isn't going to appeal to the EDC crowd.  It is meant to be a S&R light – and one that runs on a wide range of batteries, including both primary CR123A and rechargeable Li-ions. If that's what you are looking for, the SR51 is worth your consideration.

----

SR51 provided by Battery Junction for review.


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## candle lamp (Sep 15, 2011)

Great review and many thanks for your time & effort as always. Selfbuilt! :thumbsup:

Olight SR51 & Eagletac M3C4 are very similar in lumens & peak beam distance.

It's surprise that the peak beam distance of SR51 & SR92 is 396m & 425m respectively even though lumen is 800 & 1750.
The difference of the beam distance is just 29m. 

I just thought SR92's peak beam distance will be much longer than SR51 beacuse it has a bigger bezel(98mm) than SR51(62mm).
Moreover it has smooth reflector & three XM-L, but SR51 has orange peel & one XM-L.
I'm not sure why peak beam distance between the two lights is little different. :shakehead

Eidt : Dose it tell one XM-L with one big & deep reflector does concentrate the light well and throw it farther than three XM-L
with each small & shallow reflector?
(I'm wondering how it will come out if SR51 has a smooth reflector. )


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## selfbuilt (Sep 15, 2011)

candle lamp said:


> I'm not sure why peak beam distance between the two lights is little different. :shakehead
> Eidt : Dose it tell one XM-L with one big & deep reflector does concentrate the light well and throw it farther than three XM-L
> with each small & shallow reflector?


Correct - the maximum throw is heavily dependent on the size and shape of the individual reflectors (especially their depth). The overall bezel diameter of the SR92 is irrelevant, it all comes down to those individual reflectors.

As an aside, it is difficult to do deep reflector focused for throw on multi-power lights. In the few examples that I have seen who have tried (with relatively deep wells), you often get a lot of overlapping coronas that can be distracting (i.e. the overlapping peaks and troughs give you a "daisy-flower" effect). By going with smaller and shallower reflectors (that are clearly delineated from each other), the SR92 is able to produce a cleaner looking beam. The massive high-output is what allows them to compensate, producing reasonable absolute throw numbers - but it is certainly not a relatively "throwy" light, per se.



> (I'm wondering how it will come out if SR51 has a smooth reflector. )


Probably not that much more. Textured reflectors often have the greatest effect in smoothing out the corona (i.e. softening the defined edge to the hotspot). While texturing reduces absolute center beam lux @ 1m somewhat, it generally has a pretty minor effect on overall beam distance.


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## easilyled (Sep 15, 2011)

I take it that you haven't noticed any flickering on the low-mode self-built, otherwise you would have reported it?
Mine shows some mild flickering (not PWM). This would not be much of a problem outdoors, but indoors resting on its tail in "candle-mode", it imitates a candle in this way too.


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## selfbuilt (Sep 15, 2011)

easilyled said:


> I take it that you haven't noticed any flickering on the low-mode self-built, otherwise you would have reported it?
> Mine shows some mild flickering (not PWM). This would not be much of a problem outdoors, but indoors resting on its tail in "candle-mode", it imitates a candle in this way too.


No, I don't see flickering any on mine (and I would have reported it if I had ). I sometimes see flickering on some lights as the battery nears exhaustion (e.g. my UB3T, which I comment on in one of the videos) - but I consider that "normal" (or at least, common).

Certainly, flickering when in normal use with good quality cells is a bad sign. I see others have reported that issue as well on Lo ... I wonder if it was an issue with a specific batch? :thinking: Certainly no signs of it on my sample.


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## easilyled (Sep 15, 2011)

selfbuilt said:


> No, I don't see flickering any on mine (and I would have reported it if I had ). I sometimes see flickering on some lights as the battery nears exhaustion (e.g. my UB3T, which I comment on in one of the videos) - but I consider that "normal" (or at least, common).
> 
> Certainly, flickering when in normal use with good quality cells is a bad sign. I see others have reported that issue as well on Lo ... I wonder if it was an issue with a specific batch? :thinking: Certainly no signs of it on my sample.



If I was being cynical, I'd wonder if there's better QC for your samples. 
My light was detained in UK Customs, for which I had an extra wait and had to pay a hefty charge.
I don't want to go through all that again, so I'll have to live with it.


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## selfbuilt (Sep 15, 2011)

easilyled said:


> If I was being cynical, I'd wonder if there's better QC for your samples.


Something I can never rule out. Although if that's true, I wonder what explains all the poor tints and defective circuits I've come across over the years. 

One thing that is quite common (and runtime testing sometimes elicits it on engineering samples or first batch lights) is specific problems with a specific component of a circuit. This can commonly manifest as a loss of efficiency, circuit failure, or flickering. Whenever it occurs during testing, I let the manufacturer know right away - often, I find they are aware of the issue, and are already taking steps to correct it (by switching suppliers for a specific circuit component, etc.). In many cases, they send me a replacement sample from a second batch (when ready), and the problem is resolved. The Sunwayman V10A is a recent example I can think of where there was a flickering issue at low outputs on some batteries that was quickly tracked down and fixed (with dealers receiving replacement inventory).

No idea if that is the case here, but it's probably worth enquiring with your dealer or olight about. Of course, I fully understand what the joys of custom charges and delays can be like .... not always worth it, if the problem is minor. Still, if it prevents you from enjoying the light (or limits your use of it), you may to consider at least enquiring. :shrug:


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## tre (Sep 18, 2011)

Wait, the SR51 does not actually throw light the claimed 700 meters  ?

Thanks for the great review.


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## easilyled (Sep 18, 2011)

Thanks for the advice selfbuilt, the dealer that I bought the light from has been very understanding and has agreed to exchange my light.

When the going gets tough, they get going. They're obviously geared up for this sort of occurrence.


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## selfbuilt (Sep 18, 2011)

easilyled said:


> When the going gets tough, they get going. They're obviously geared up for this sort of occurrence.


Glad it is working out for you. With a good manufacturer, that should be case (i.e. you wouldn't want a dealer stuck with defective inventory or exchanges). I think most realize that it is all part-and-parcel of being on the bleeding-edge of new lights as they come out.


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## easilyled (Oct 3, 2011)

My replacement SR51 arrived today and I am happy to say that this model appears to be without the afore-mentioned flickering on the lower level.


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## cummins4x4 (Oct 3, 2011)

Great review. Had a problem with mine. After the first few hours it started switching to low by itself c/w a buzzing noise. It would then switch to high and would keep doing this. Switched batterys (UF 18650 2600's) with the same result. It is on its way back to GG and they are sending a replacement. After reading the other SR51 threads I am wondering if it could be the batterys?


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## Brasso (Dec 30, 2011)

Has anyone tried fitting 3 17670's in the battery carrier?


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## cummins4x4 (Dec 31, 2011)

cummins4x4 said:


> Great review. Had a problem with mine. After the first few hours it started switching to low by itself c/w a buzzing noise. It would then switch to high and would keep doing this. Switched batterys (UF 18650 2600's) with the same result. It is on its way back to GG and they are sending a replacement. After reading the other SR51 threads I am wondering if it could be the batterys?



Got the replacement light from GG. Been running it everyday for a couple of months. Stuck the UF batteries in just to see if I could duplicate the original problem, it's not the batteries. Running on AW 2900's now, again no issues. Great service from GG BTW.


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## Brasso (Jan 6, 2012)

FYI,

I put 3 AW 17670's in my SR51 and while they will fit and the light will come on, it only comes on in a very low output. I'm guessing it can't pull enough volts from the batteries. I only tried them for a few seconds as I fear using them any longer would be unwise.


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## HKJ (Jan 6, 2012)

Brasso said:


> FYI,
> 
> I put 3 AW 17670's in my SR51 and while they will fit and the light will come on, it only comes on in a very low output. I'm guessing it can't pull enough volts from the batteries. I only tried them for a few seconds as I fear using them any longer would be unwise.



That is no surprise, the light needs 4 volt to work and 4.5 volt to work at full brightness. If you use the special 2x18650 holder it will take two 18650 in series and you will get full brightness.


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## selfbuilt (Jan 6, 2012)

This thread revival reminds me that I have another outdoor comparison pic from my Crelant 7G5 review (that shows the SR51 along with the Thrunite Catapult):






:wave:


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## Brasso (Jan 6, 2012)

Those are the pics I was looking for before I got the SR51. It's a great all purpose heavy hitter. 

I did get the 18650 battery carrier with mine. I just wanted to see if 3 17670's would work. They won't.

Now, does anyone have 3 IMR's to try.


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## selfbuilt (Jan 6, 2012)

Brasso said:


> I did get the 18650 battery carrier with mine. I just wanted to see if 3 17670's would work. They won't.Now, does anyone have 3 IMR's to try.


3 IMR in parallel (i.e. 3x IMR 17670 in the standard carrier) won't do any better, since max voltage is still only ~4.2V.

You could run 2 IMR 16340 (RCR) in just one channel of the standard carrier - but runtime would be rather short. In essense, this is the same as 2x18650 in the dedicated series-linked 18650 carrier, just with lower capacity cells (i.e. 2x4.2V = 8.4V, either way).

Even if you could rig 3x IMR is series, you would probably blow the circuit. Olight reports a range of 4.5-8.4V, so that basically means 2x sources only.


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## Oztorchfreak (Jan 30, 2012)

Hey good job as always Selfbuilt.

Your tests allow us all to pick what we need a lot easier.

I have the Olight SR50 and it looks like you never did a test on it.

I bought the SR50 just recently for under $100 AUS.

It came with the 2 x 18650 battery carrier and the original 6 x CR123 carrier.

That was the downfall of the SR50 of not providing for 18650 operation.

What were the battery capacities used in your SR51 Runtime and graph tests?

CR123A -

RCR123 -

18650 -


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## selfbuilt (Jan 30, 2012)

Oztorchfreak said:


> I have the Olight SR50 and it looks like you never did a test on it.


That's right, I never tested the SR50.



> What were the battery capacities used in your SR51 Runtime and graph tests?


The CR123As are Titanium Innovations cells, labelled as 1400mAh. But I can tell you from my current battery testing that they continue to perform comparably to all the major made-in-the-USA brands.

The RCRs are standard black-label AW protected, labelled as 750mAh. I believe most people consider this to be an over-estimate (e.g., the AW 14500s are similarly rated, but typically have >20% more capacity). Hard to find reliable numbers for the RCR capacities.

The 18650s are original button-top AW protected, labelled as 2200mAh. This capacity measurement seems fairly accurate to me, as runtimes to scale up pretty well again newer high-capacity cells (although that depends on specific current levels).


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## kj2 (Feb 3, 2012)

Question; (Hope that someone reads it, and can answer it  ); Olight SR51 or Fenix TK41? Which light is brighter? And which one will throw further? Which one would you choose?


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## Oztorchfreak (Feb 3, 2012)

They are very close in beam spill and throw.

Do you really want to keep charging 8 x AA batteries?

The SR51 has the versatility of being able to use 6 x CR123As, 6 x RCR123s or Li-ion 18650s.

I have the SR50 with the SST50 in it with the battery carrier for both of the battery sizes.

I have used the 2 x 18650 carrier and it works great with 2 x 18650 2900mah Li-ions in it and I love the feel, the spill, the throw and the strobe.

In Australia the Olight SR50 has come down a lot in price to under $100 AUS and it included the 18650 battery carrier and the CR123 one.

Because the price had dropped here and I knew about the 18650 option this torch (SR50) was a bargain in Australia.

But with the addition of the 18650 battery carrier the torch works just as good as the SR51 in my opinion.

It boils down to personal taste and battery options in my opinion.

Try looking in google for flashlight comparisons on youtube.

I found one comparison that has 73 flashlights compared at the same site under the same conditions including the Olight SR50, SR51 and the Fenix TK41.

PM me if you need any more info on that comparison site that I go to.


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## HKJ (Feb 3, 2012)

kj2 said:


> Question; (Hope that someone reads it, and can answer it  ); Olight SR51 or Fenix TK41? Which light is brighter? And which one will throw further? Which one would you choose?



I have compared them in this beamshot, together with some other lights. Which one you will chose depends on your user interface preference and battery preference.


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## tomtetom (Feb 3, 2012)

I think the SR51 is better, because it has got more lumens and a more concentrated Beam.

Tom


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## kj2 (Feb 3, 2012)

Thanks everybody  - I think i'm gonna buy the SR51. Already have the TK41, but he needs a brother next to him 
Now, I know a website which sells it for €130,- including shipment in EU. Do you guys know a cheaper shop in the EU?


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## keithhr (Oct 30, 2012)

I've been a member of the cpf for over 10 years, currently own 5 olights and when I turned on my SR51 to do a performance check which I do every few weeks, it was
dead. I examined the led and it looked milky and strange. I contacted olight and going gear which sold it to me, and it is not a cheap light and the best I could do was be
told that I had to wait 2 to 3 months for it to be sent to China so they could repair it. I am really unhappy with the response from olight that could have simply sent me a
replacement head. Over the years, like most here, I've spent a fortune in flashlights of all descriptions from Hid to the fenix 4c light, power on board and you name it. I am
writing to you all because I've never experienced such a weak response, I will purchase something else, even though I have a couple of battery holders for this light. Nobody
is willing to act like I am a valid purchaser, it would never cross my mind to scam anyone and I do have over 530 ebay feeedbacks with 100% positive, All I can say is let
the buyer beware when dealing with this company which was one of my favorites before this happened. I carry my SR51 for security purposes and never imagined that in this
day, a flashlight could fail from inactivity. I periodically take our my dual 18650 batteries and put in fresh ones that have been recharged. I own a few Jetbeam lights, the big
fenix tk70 but it's a bit big to carry, anyone have any failures with their Olight?
just curious
Keith


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## drb46 (Dec 5, 2012)

I bought a SR51 in June of 2012 and it has never worked right. I have tried both types of batteries and the batteries are not the problem. The dealer has offered to send me the parts to fix it, but I don't really know what parts to request. The light flickers or won't go into medium mode at all, and using the 18650s it is not reliable in high mode. Can anyone suggest what parts to request and is there anyone here that would work on it (for a fee)?


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## selfbuilt (Dec 5, 2012)

drb46 said:


> I bought a SR51 in June of 2012 and it has never worked right. I have tried both types of batteries and the batteries are not the problem. The dealer has offered to send me the parts to fix it, but I don't really know what parts to request. The light flickers or won't go into medium mode at all, and using the 18650s it is not reliable in high mode. Can anyone suggest what parts to request and is there anyone here that would work on it (for a fee)?


I don't what parts they would send you that you could do yourself. If the light doesn't work properly with either the 2x18650 or 6xCR123A battery carriers, it sounds like a circuit problem that would require a RMA to the manufacturer, sorry.


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## drb46 (Dec 5, 2012)

selfbuilt said:


> I don't what parts they would send you that you could do yourself. If the light doesn't work properly with either the 2x18650 or 6xCR123A battery carriers, it sounds like a circuit problem that would require a RMA to the manufacturer, sorry.



Well that's just what I was thinking. Thanks for the confirmation. I requested a RMA from the dealer, but he wants to send me parts.......oh well, live and learn.


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## kj2 (Jul 30, 2013)

I asked Olight on Facebook if the SR51 will be updated. They answered, that there is a update coming in the next 60 to 90 days.
So yes, we have to wait a while- but there should be a update coming


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## MichaelW (Jul 30, 2013)

I'd hope than an updated version, if it retains a single xm-l2 puts out 1350 lumens on high, and has at least two lower levels.


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## berry580 (Oct 9, 2014)

Hello, according to the rating in this review, the sr51 can achieve 0.25 lux at 396m. How come the rating for the sr51 have changed to 451m in the sr52 review?http://www.candlepowerforums.com/vb...R123A)-Rechargeable-review-BEAMSHOTS-RUNTIMES

Thanks


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## selfbuilt (Oct 9, 2014)

berry580 said:


> Hello, according to the rating in this review, the sr51 can achieve 0.25 lux at 396m. How come the rating for the sr51 have changed to 451m in the sr52 review?http://www.candlepowerforums.com/vb...R123A)-Rechargeable-review-BEAMSHOTS-RUNTIMES


It's because of the updated NIST-certified lux meter used to do the calculations now. This is explained in the review text, right above the table (i.e., the bit about the switch to the orange highlights in the table). The are the numbers to go by.


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