Olight S1A & S2A measurements (AA, XM-L2)


Dec 22, 2015
Disclaimer: Olight sent me these lights to review for free.


The S1A and S2A are the latest small flashlights from Olight. They both use AA batteries, one for the S1A and two in series for the S2A. Both support alkalines, lithium ion primaries (bundled in the package) and NiMH rechargeable batteries.

The S1A can also utilize a rechargeable 14500 lithium ion cell to enable turbo output (600 lumens). With other batteries the output is limited to ~200 lumens. The two batteries in S2A are able to provide enough voltage and current to enable turbo even with primaries and NiMHs. Using a high capacity 14500 is advisable, since it offers higher maximum output and no downsides compared to NiMHs.

You cannot use 14500s in the S2A!

Unlike in the SxR-series there is no in-light charging with the SxA-series. You need an external battery charger. Preferably a universal one so 14500s can be used in the S1A.





The S1A has a magnet in the tailcap.

The lights come bundled with:
Pocket clip
Lithium battery/ies
User manual






Dimensions and weight

Length: 132.1 mm
Head width: 21 mm
Weight: 37g (without batteries)

Length: 79.7 mm
Head width: 23 mm
Weight: 56g (without batteries)

Add 30g for an Eneloop, 15g for a Lithium primary and 19g for a 14500.

An Olight branded 14500 lithium ion rechargeable is an optional extra for $5.40 at olightstore.com. Also available are a white or orange traffic wand ($3.90) and a universal two bay Omni-Dok charger ($21.90).

You shouldn't leave the light unattended, since it seems there is no automatic low voltage cutoff. After the flickering started, I measured the Eneloop at 0.90 volts. Not dangerously low yet. If you can actually see the light when running it low, there's no problem though since the flickering is impossible to miss.

If you want to use a 14500 battery, the S1A requires a smallish button on the positive terminal. For example an Efest 14500 raised platform batteries did not work in my testing. Keeppower, Eagtac and a button top version of the Efest worked fine. There's no difference in output between a high current and a normal 14500.

Since both lights use an electronic switch, they need current to flow in standby. The standby current is negligible:
S1A: 5,5µA
S2A: 1,1µA

The S2A is available in four different colors: black, grey, blue and yellow. All have rubberized grips and in all but the black one the rubber has a glow-in-the-dark paint.



Both use a cool white Cree XM-L2 emitter. The output is rated at 600 lumens for the S1A and 550 for the S2A. According to the mfg specs the stepdowns on turbo are:
S1A: 600 lumens to 300 lumens at 1 minute
S2A: 550 lumens to 260 lumens at 3 minutes


Eneloop AA battery, Olight S2A (2xAA), Olight S1A (AA), Klarus Mi7 (AA), Olight S1-Cu (CR123), Olight S10 (CR123), Astrolux E01 (18350).



Olight S1-Cu, Olight S2A, Olight S1A, Olight S10, Klarus Mi7.

Beam and tint

The TIR optics provide a round and large hotspot with very little spill. Light output at angles over 10 is minimal. The beam is similar to the popular S1 Baton. Since the led and optics are the same, the S1A and S2A are practically identical. Some differences might be due to centering of led and miniscule production differences.


S1A beam intensity vs. angle (14500 Turbo)


S2A beam intensity vs. angle (Eneloop Pro Turbo)

Beam comparison (gif) between similar sized lights with a wall and in a forest.



The Olight S10 and Klarus Mi7 have a lot more spill with a smaller hotspot that fades gradually. Mi7 also has significantly greater throw, even the lumen output is about the same (540 lm). The Astrolux E01 has a more neutral white tint and greater output than any of the other lights.


S1A tint in different brightness modes.


S2A tint in different brightness modes.


S1A tint in different parts of the beam.


S1A tint in different parts of the beam.

Since I was provided with two S1As and four S2As to test, I measured the consistency of tint between them. Although the difference seems big in the graph below, in reality it's not that huge.

Tint of different samples (on turbo).


The beamshot comparing the farthermost lights on the graph (S1A #2 and the Blue S2A). The S1A is greener and warmer in tint, but as they say and we all know the camera adds three degrees of difference. Again, in reality the difference in tint and color temp is smaller. Some might call this tint lottery, but without a direct comparison, it would be difficult to tell the difference between two samples.

Spectral data and color rendering

For spectral information and CRI calculations I use an X-rite i1Pro spectrophotometer with HCFR, Babelcolor CT&A and ArgyllCMS spotread for the graphs and data. For runtime tests I use spotread with a custom script and an i1Display Pro because it doesn’t require calibration every 30 minutes like the i1Pro.

Explanation of abbreviations

CCT = correlated color temperature, higher temperature means cooler (bluish)
CRI (Ra) = color rendering index consisting of 8 different colors (R1-R8), max value 100
CRI (R9) = color rendering index with deep red, usually difficult for led based light sources, max value 100
TLCI = television lighting consistency index, max value 100
CQS (Qa) = Proposed replacement for CRI, RMS average of 15 color samples
CRI2012 (Ra,2012) = Another proposed replacement for CRI, consists of 17 color samples
MCRI = Color rendering index based on the memory of colors or 9 familiar objects
*NEW* Read more about the IES TM-30-15 method here
TM-30 = The newest color rendering method using 99 samples. Preferred for comparing LEDs.
TM-30 (Rf) = Accuracy of colors, fidelity index. Replaces CRI(Ra).
TM-30 (Rg) = Gamut of colors, saturation index. Higher number means more saturated colors.
Tint dev. ("Duv" in the CTA screenshots) is the tint's distance to the black body radiator line in the CIE graphs. The higher the number, the greener the tint. 0,0000 means absolutely neutral white and negative numbers mean rosy/magenta tint. Anything over 0,0100 can be described as visibly green.


S1A spectrum.


S2A spectrum.


S1A CRI data.


S2A CRI data.


Runtimes and output

Please note: lumen measurements are only rough estimates
My diy 40 cm integrating styrofoam sphere has been calibrated using a Fenix E05 on high with manufacturer’s claim of 85 lumens. Verified with an Olight S10 and Olight R50 Seeker that have been measured with a Labsphere FS2 integrating sphere by valostore.fi. Results may be more inaccurate with especially throwy or floody lights.







The lights get warm only on turbo. There is no real danger of overheating even when left unattended unless it is direct sunlight inside a car or something just as ridiculous.



PWM is not used, but there is some high frequency switching on the moonlight mode on the S2A. The flickering is noticeable only by video cameras or by moving the light fast, not distracting in real use. S1A has constant current output even on moonlight.



Strobe has a frequency of 10 Hz.


For their size and batteries used the Olights produce a fair bit of lumens. They cannot touch hotroddy 18350 flashlights though, which to be fair, are a bit larger. The one click on/off and hold to change modes type user interface is intuitive. There's also mode memory (turns on on the last mode used) and easy access to different modes. Both the turbo and moonlight can be activated from off and strobe cannot be accidentally turned on (needs a triple click).

As is usual with Olight, there is only one LED option: cool white XM-L2 with mediocre color rendering. There might also be some tint differences between samples. Some of the tested lights were a bit greener in tint while some were more of a natural cool white.

On the Olight S1A there's no reason not to use a 14500 lithium ion rechargeable, since it offers better output than an Eneloop with no downsides. Runtimes on lower modes are also similar. In the S2A Eneloops are prefered.

+ Output in their class
+ Stable regulation in all but turbo mode
+ Easy to use UI with last mode memory
+ Direct access to turbo from off and from any mode (double click)
+ Direct access to moonlight from off (long press)
+ Short click to turn on and off
+ Easy lockout via unscrewing the tailcap quarter of a turn (no electronic lockout)
+ Negligible standby current
+ Grippy rubber handle on the S2A
- PWM on moonlight mode (albeit not distracting)
- Low CRI
- No neutral white option
- Some might call the difference in tint between samples a lottery
- The S1A needs a button top 14500


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