Niwalker BK-FA30S review w/ measurements (XHP35 HI, 4x18650)

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maukka's picture
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Niwalker BK-FA30S review w/ measurements (XHP35 HI, 4x18650)

Disclaimer: The Niwalker BK-FA30S was provided for testing by manufacturer free of charge

The newest long range XHP35 HI thrower from Niwalker promises a lot. With a specified range of 1600 meters it should be in the same class as the Thrunite TN42 and Acebeam K70.

What sets the BK-FA30S apart is the triple switch system, which lets you program two desired modes to the auxiliary buttons while the main switch operates in the usual way.

Manufacturer’s specifications
Battery: 4×18650 (accepts button and flat tops, protected and unprotected, batteries not included)
LED: Cree XHP35 HI in cool white
Waterproof: IPX7 (no depth rating)
Impact resistance: 1.5 meters
Mode memory: yes (except maximum and special modes)
Low voltage protection: side switch led indicator when battery voltage low, LVP cutoff at 10.9V (2.7V per cell)
Thermal regulation: yes
Lockout: electronic

Output specs
Maximum output: 2200 lumens
Other output levels: 1500/900/300/25/2 lumens
Light intensity: 650000 candela
Beam distance: 1600 meters
Special modes: strobe, sos, beacon, warning flash

Measured dimensions and weight
Length: 226mm
Head width: 100.2mm
Handle width: 50.5mm
Weight: 742g plus 190g for the batteries

Box and contents

The box is plain brown cardboard with the specs attached on the top. The light is shipped unassembled to save space, you’d never think a 100mm thrower fits there.

Bundled in the box with the light:
Wrist strap (missing from the pictures)
Two spare o-rings
User manual

I wished there was a longer shoulder strap instead. Other retaining options include standard tripod threads.

Physical appearance

The BK-FA30S is a big light, but not too heavy, lighter than the Thrunite TN42 and the Astrolux MF02 for example.

Batteries are inserted into a 4S carrier. The springs are long enough to make good contact with unprotected flat tops. Protected button tops also fit fine. Protection circuits aren’t absolutely necessary, since there is low voltage cutoff in the driver. Just remember to use similarly aged and identical model batteries for maximum safety.

The current draw isn’t too high, only a couple amps, so the basic NCR18650Bs with protection will work fine.

The tailcap has a locator light which is activated via the switch. It alternates between red and green.

User interface

There’s three switches on the side of the light. The middle one acts as a normal electronic switch with memory. The surrounding ones can be programmed to any of the modes including Turbo/L6, strobe, sos and warning flash.

The main switch cycles normal modes L1 through L5, and the maximum output is activated momentarily by pressing and holding the switch from off. If you release the switch and press is again right away, L6 will stay on.

The light operates as follows:

From off
Main switch click activates the previous used mode (L1-L5)
Main switch hold activates momentary turbo (L6), release and click again will put the light on constant L6
Main switch double click activates strobe

From on
Main switch long press cycles normal modes (L1-L5)
Main switch double click activates special modes which can be cycled with a long press

The switches don’t quite have the same quality feel to them as the TN42. The travel is a bit larger and there’s a bit of play if you press the edge of them. Nothing serious though, and there was no actuation problems during my testing. There’s a good distinct click to them too.

The memory with the extra buttons and momentary turbo with a hold of the main switch are great. You can also switch from momentary turbo to constant turbo by releasing and pressing the switch again.

There was some strange behavior to the main switch memory. It doesn’t always memorize the mode if you use either of the auxiliary buttons.

Say you have the left button as L1 and the right one as L6. You turn the light on with the main switch and cycle up to L2. Now the L2 is memorized if you turn the light off and switch it back on with the main switch. If you activate L1 by pressing the left switch and turn it off using the same left switch, the middle button turns the light on L1, not mid.

If you click the light on with the right switch to the memorized L6 and then turn the light off the main switch will always turn the light on L2 regardless of the mode you previously used.

Size and beamshot comparison

The BK-FA30S is a big light. Nowhere near the BLF GT, but bigger than the TN42.

Niwalker BK-FA30S, Thrunite TN42, Astrolux MF02

Individual beamshots

Despite the measurements, the difference between the three throwers is small. What is apparent though, is that the TN42 has best focused spot with least spill. Its warmer color temperature is also more useful in real life.

Individual beamshots

Beam and tint

The beam is what you’d expect from a large smooth reflector light using the Cree XHP35 HI. There’s a small well focused hotspot which transitions to the spill in two phases.

Even though the tint shift can be seen from the measurements, it is moderate and not distracting at all, since the intensity outside the hotspot is very very low in comparison.

The tint changes a lot in different modes. Higher modes are cooler and more neutral (closer to the black body line). None of the lower modes look that obnoxious to me though.

There’s no rings or other visible artifacts in the beam.

Tint in different brightness modes.

Tint in different parts of the beam.

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
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.

If you have an hour to spare, I recommend watching this presentation on IES TM-30-15 which also shines light into color rendering in general.

CRI data on maximum output (L6)

CRI data on mid (L3)

CRI data on moon (L1)

Output and runtimes

All tests were done with a set of unprotected Samsung 30Qs.

Lumen output matches the manufacturer’s specifications, but the throw lags behind a bit. I would probably get a bit higher numbers with longer measurement distances. Throw was measured at 5 meters. The difference to the Thrunite TN42 is only about 10% which isn’t very visible in real life.

However, the output decreases as the batteries deplete. The BK-FA30S still produces more throw than the Astrolux MF02 for well over an hour. Lumen output is very comparable to the Thrunite TN42 over the whole runtime but due to lower efficiency, the Niwalker gets a bit hotter and has to be actively cooled not to cause damage to the batteries.

Low voltage protection

The light automatically shuts off when the battery pack drops below a certain voltage (10.9V). This works great as long as you don’t have a badly mismatched set.

The main switch has a backlight to indicate battery voltage. I measured the following thresholds:
Green >12.9V
Red 11.8-12.9V
Blinking red 10.9-11.8V
The light shuts off below 10.9V (2.7V per cell)

Standby current

Due to the electronic switch, there’s some parasitic standby current when the light is switched off.

50µA at 16 V
40µA at 12 V

The drain is insignificant and it would take 30 years to drain a set of 3000mAh batteries.


I measure the flicker with a Thorlabs DET36A/M photodetector and an oscilloscope. Here are the explanations for the data acquired.

Frequency – the rate of flicker in hertz. If this is over 10kHz, there’s usually no reason to worry about visible flickering
Modulation – also known as percent flicker which is calculated by (max level – min level) / (max level + min level). 100% modulation means that the light is turning completely off during the cycles like on PWM controlled output
Duty cycle: the relative time the light spends above the mid level during one cycle. 50% means that the light is above mid (“on”) 50% and below mid (“off”) 50% of the time. Lower duty cycle results in more visible flickering or strobe effect
Index: flicker index is calculated using the area under the curve (link is external). This integral is separated into area above and below the average output. The index is the area above that average divided by the total area. A pwm light with a duty cycle of 50% will have a flicker index of 0.5, but it is more useful with more complicated periodic waveforms, especially those whose modulation is less than 100%.

Snob index: a rating, which tries to convey a single number for flicker visibility
1-5% - Probably not visible to the naked eye (high frequency PWM, >10kHz or low modulation at lower frequencies)
5-10% – Might be visible to the most sensitive people who know what to look for and try hard enough (incandescent)
10-20% – Sensitive people will see it at least on bright reflections, probably not a dealbreaker yet in general use
20-50% – YMMV area. If you can usually spot mid frequency PWM, you’ll easily see the flicker
>50% – Visible to most people at least on some occasions (low frequency PWM, <200 Hz)

PWM is used on all the modes except maximum (L6), although it also shows some ripple. The frequency is high at over 20kHz so the flicker will not be visible to the naked eye on any of the modes (flicker snob index 0%). A camera with a high speed shutter may pick it up though.

Output vs. time at high sampling rate

On L5

Other modes



Strobe operates at 10.2 hertz reaching an output a bit above maximum constant level (L6). Here’s the transition from L6 to strobe.


Niwalker says the BK-FA30S has “advanced thermal protection circuit prevents overheating”. It will very slightly limit the output at extreme temperatures, but to prolong the life of the light and batteries, I recommend stepping it down manually when the light gets too hot to hold.

I measured 80°C on the head of the light after 22 minutes on maximum output. At this point the handle with the battery carrier had reached 70°C which is over the recommended operating temperature of most 18650s. The light gets uncomfortable to hold in about 5-10 minutes depending on the environment.

On the second highest mode (L5) it takes about 8 minutes for the head to reach 50°C and 20 minutes for the handle. Maximum head temperature was 65°C at 40 minutes.

Rest of the modes make it possible to hold on the light indefinitely. L4 reaches 47°C maximum temperature on the head at one hour.


The Niwalker BK-FA30S can battle with the best of them. It’s practically on par with the Thrunite TN42 in throw while offering just a bit more output. The prices are also comparable at about $200.

Due to a simple current regulated driver, the power drops as the batteries drain. On the lower modes the efficiency is also a bit lower than on the competitors, but not much.

The programmable auxiliary switches are a great addition to the already easy to use interface. You can save any mode including strobe to either side switches for quick access from off or on. There are some quirks between the main switch memory and the programmable buttons though, so you might not always get the mode you were expecting.

The tint on the higher modes is very neutral cool white (near the black body line), but I would like to see a warmer white version available as well (4000-5000K). As is usually the case with the Cree XHP35 HI, the shift in tint isn’t very visible from hotspot outwards.

Even though PWM is used to regulate current, it is fast enough (>20kHz) not to be visible to the naked eye. Despite the use of PWM, the tint is significantly cooler when the output is increased.

Overall the construction and quality is good, which also shows in the good output and throw measurements.

+ Great throw distance
+ One click on, one flick off
+ Two instant access memory switches
+ Shorter flat top batteries make good contact in the carrier
+ Fits long protected button tops batteries as well
+ No visible flickering
- Only available in cool white
- Turns very cool on higher modes
- No output regulation on any mode
- Some strange behavior with the main switch memory

Edited by: maukka on 02/11/2018 - 02:44
Last seen: 6 days 3 hours ago
Joined: 10/21/2012 - 06:17
Posts: 191
Location: Republic of Korea

Thank you for detail review~~!

DENGOH's picture
Last seen: 1 day 18 hours ago
Joined: 10/06/2012 - 05:26
Posts: 1767

So difficult to beat TN42.
Luckily we have BLF GT, though a bit bigger size.

cool i'll see you when you get there

freeme's picture
Last seen: 2 min 17 sec ago
Joined: 11/14/2013 - 22:00
Posts: 5983

Reflector is well polished.

Nicolicous's picture
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Joined: 04/16/2016 - 08:28
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Location: Australia
DENGOH wrote:
So difficult to beat TN42. Luckily we have BLF GT, though a bit bigger size.

BLF GT is not practical for every use TN42.

DENGOH's picture
Last seen: 1 day 18 hours ago
Joined: 10/06/2012 - 05:26
Posts: 1767

YA, BLF GT size and weight will make many sell their GT.

cool i'll see you when you get there

Lexel's picture
Last seen: 8 hours 1 min ago
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Location: Germany

there is a error in 435kcd at 60s this should be 535kcd

I also observed the odd memory behavior with the switches and got a bit more try and error getting to this conclusion

Also the UI listed on the website does not match with my sample, also if you do the double click too fast then the light does not recognize it, the range of timing here needs to be better. If you have not stored Turbo to a side button you have to turn the light off to get to it.

And the option to configure the side buttons to a momentary mode change then automatically turn back to last memorized mode

I have also found some inconsistencies in the UI

for example if I switch the light on with an auxiliary button then click the main switch the light turns off
while I turn the light on with main button switch to aux buttons then main switch gets me back to memorized modes

Another odd thing is this
I have a medium mode memorized for main switch
I turn on the light with Turbo on auxiliary button and turn it off with the same auxiliary or the main button,
then the light comes on in moon the next time I switch it on with main switch
after this I turn the light on with a blinky mode on the other auxiliary
now I switch it off with that button or main button
and now switching on the main switch recognizes again the stored medium mode

Next thing
I switch the light on with blink mode on aux1 or switch it on with main button then switch to aux1
then switch to turbo on the 2. aux button
if I click now the main switch I do not get the memorized light level instead I get again the blinky mode of aux1 button

If the light is switched on with momentary Turbo then hold for Turbo it is not possible to change modes with main button


I am not sure, but maybe the LED is not focussed very well as the throw is behind the TN42 with same sized reflector

The driver needs definately more love to get it bug free and with a better buck controller like the BLF GT,
I made a version of the GT design fitting this light with the auxillary switches going to 1/10 power or 10 times more power or turbo, prototype board still on the way here

maukka's picture
Last seen: 9 hours 8 min ago
Joined: 12/31/2015 - 04:15
Posts: 1220
Location: Finland
Lexel wrote:
there is a error in 435kcd at 60s this should be 535kcd

Fixed. It was actually supposed to be 556kcd.

I agree, they need to refine the UI quite a bit. The interaction between the aux switches and main switches is sometimes very erratic. Too much of the behavior depends on whether you turn the light on with the main switch or an aux switch in the first place.