Thorfire TK4A Review (4xAA)

Thorfire produces a good variety of flashlights from very small EDC lights to large thrower type lights.
I have tested almost the full EDC line of their Li-Ion powered flashlights.
This time they offered me their AA powered TK4A for test.
A good chance for me to add a new non-Li-Ion flashlight to my review list,as I don't have much in it and actually I don't use NiMH/Alkaline AA batteries from a few years now.
The NiMH and alkaline batteries have their advantages over the Li-Ion alternative.
Despite the fact that they store less energy and weight more,many people prefer the safety and availability of the AA batteries.
Storing and using these type of batteries has much less requirements and some spares can be found easily when needed.

Specifications and instructions from manufacturer(copy/paste)

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Uses Cree XP-L LED with a lifespan of 20 years
Modes: Low/Mid/High/Turbo, hidden Strobe and Moonlight
Battery: Uses 4*AA NiMH/NiCd/Alkaline(Not Included)
Material: Made of Aircraft-grade aluminum
Size:approx 115mm(Length) * 41mm(Body Diameter)
Weight: 178.5 gram (excluding batteries)
Water resistant: IPX-8, underwater 2m
Impact resistant: 1m
Intensity: 11600cd (Max)
Distance: 460m (Max)

Battery Capacity Display
The switch button have a battery indicator light. The light will displaying “Green”, if the battery capacity is higher than 50%.
If it is lower than 50%, it will turn to “Orange”. When it less than 15%, it will changed to “Red”.

Operation
Click the side switch to turn on, keep on clicking to change brightness levels from Low-Medium-High-Turbo, double click to activate Strobe mode,
and another click goes back to the previous brightness level, press and hold the switch to turn off. When the light is off,
press and hold to activate Moonlight mode, click to turn off.With the light OFF, press and hold the side switch for 1 second goes to Moonlight.

 
Intelligent Memory Circuit
The flashlight will memorize the last used (more than 3 seconds) brightness level.
The next time you turn the flashlight on, it will activate on the last used output.

Package includes
> 1 x ThorFire TK4A flashlight
> 1 x Use Manual
> 1 x Lanyard
> 1 x Carry Pouch
> 2 x O-ring

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Thorfire TK4A has a relatively straight,clean design with no deep groves,deep cooling fins or any 'exotic' looking curves.
Noticeable is the large and clear brand name with the logo. No serial number on my sample.Can't confirm if it is usually available.

The TK4A has a glossy black anodizing.No distracting scratches or dents on my sample.The anodizing is also sufficiently consistent.
The whole battery tube and most of the tailcap have fine,not aggressive knurling for a good grip in hand.
There are four cooling fins-not very deep.I could say that they are not a main factor in the heat dissipation circuit.

The TK4A can be operated by an electronic side switch.
My impressions of the switch so far are-It does produce a nice click sound,so I can know for sure that I have pressed the switch to the needed depth;
Its diameter is sufficient for my thin fingers;The switch sits on the same level with its metal retaining ring,maybe a little higher;There is no much protection of pressing it accidentally;
It is not quite soft,but I found it less resistant to pressure than expected;
The switch has integrated LED color indicator in the center,indicating battery state and light On position;

This is the standard packaging for Thorfire. Sturdy cardboard box.
The flashlight was in a bubble bag as there was an impact insulating foam on top and bottom of the box.

Size comparison picture with other flashlights.
The TK4A is my first flashlight of this type,so I chose a few 18650 flashlights.
(Left to right side) Thorfire VG25(158gr.)- Thorfire VG15(118gr.)- Thorfire TK4A(276gr.), UFC8(195gr. for the Thorfire C8s version), Nitecore EC4(262gr.)
and two AA batteries on both sides. The TK4A can be easily defined as a compact light,if you don't mind the diameter and the weight.

 
8 mm switch diameter. 30mm diameter reflector. Cree XP-L LED.

My sample came with a good lanyard and two spare O-rings in the set. I can see a holster on the official pictures but can't confirm if only my package lacks it.

Below is the TK4A in my hand.

Anodized,rectangular cut threads. Tailcap lock-out is not possible as all batteries are constantly connected because of the spring/+point connection in the tailcap.


Two metal pins have to go in their respective hole in order to be able to close the tailcap.
When inserting the batteries,especially in the dark,the user should take some care of the correct direction of each battery as they are electrically connected in series and two by two in a different direction.
Aligning the pins takes some time.

Here is another look at the battery compartment and the tailcap.

My sample had a lot of metal filings,probably remnant of the two holes drilling process.
I would recommend to check out your sample and clean it if needed.
The filings may affect the electrical circuit and the smooth screwing of the tailcap.
Trying to clean the surface around the holes,I found that the inner part of the flashlight/battery tube is not anodized,but painted with some kind of black paint or polish.

30mm diameter reflector with smooth reflective surface.
It is most likely made of aluminum. Well centered Cree XP-L LED. Cool white light.
The glass lens seems clear without anti-reflective coating.

Runtime Test
As usual I tested the flashlight on its highest mode first. This allows us to see the optimal performance of the flashlight-how good is its driver.
I used 4 low self discharge NiMH batteries.They were used for quite some time and probably do not represent the maximum that can be taken out of the TK4A,
but still the step down timing and lumen readings should be correct.
I tested also High mode,which can be seen on the second graph.

On the first graph we can see the full length Turbo mode-activating the flashlight loaded with fresh batteries,vs the light restarted after its programmed step down.
Take a look at the second graph for a better view of the first minutes.

Here we can see the difference in the brightness after each restart.
The output will be constant as long as the batteries can keep their voltage under load.
The step down is timed to three minutes after activation. The Turbo mode can be restarted if needed.
The output after step down is equal to High mode=350lm.
In my test it gets lower after each restart-I restarted only 3 times.

This graph shows the compared performance on Turbo and High mode.
The TK4A is programmed to step down to Mid mode after working on High mode for 30 minutes(this is stated also in the instruction sheet).
It is interesting to note that this step down is also applied to Turbo mode 30 minutes after its step down to High mode.

My Lumen measurements:
Turbo mode= between 900Lm and 1000Lm initial brightness depending on the batteries;
High mode= 350Lm
Mid mode= 160Lm
Low mode= 18Lm
UltraLow = hard to measure correctly;

I don't detect PWM with a camera or basic oscilloscope.
Because of the electronic switch,the power source is constantly connected with the driver which results in some amount of standby power consumption.
I still did not manage to measure it correctly and once I do it,I will post the results here.
Yet,if you want to prevent this parasitic discharge when storing the flashlight for a long period of time,the only way is to remove the batteries.


Beam profile
My copy of the TK4A produces Cool white light-relatively clear white at the hotspot with yellowish corona around it.
Compared to cleaner white beams,the TK4A's beam may look a little greenish.

White wall.

1 meter
1/20sec
All modes plus comparison with other flashlights.

1 meter
1/100s

5 meters
1/6 sec

Noticeable from the beamshots is that the TK4A's beam is pretty well focused and allows good beam range.
The larger reflector without texture allows more light to be focused in the center of the beam,especially compared to the smaller Olight S30 and Thorfire VG15/25.
1/50

After testing Thorfire TK4A and using it when possible,my impressions are good.
The beam is good,with no bad artifacts.No bad tint in regular use.
Some people may not like the cool white light,depending on their preferences.

My personal thoughts- I would prefer more diffused light,especially for a flashlight of this kind,which I don't expect to throw very far.

It is hard to get used to the UI if you use a lot of different flashlights like me. I prefer identical operation for On and Off.
I usually don't like to wait even half a second to get the needed light,and I prefer to turn it Off quickly.
This is my preferred way of using a flashlight with frequent On/Off.
If you use the flashlight for long periods of time without many pauses the press and hold On/Off should not cause a trouble.
An advantage of the UI with press and hold Off is that the mode changing is quicker-just a single brief press.

Activating Moonlight mode with press and hold operation and turning it Off with a brief press may be confusing,as this is exactly the opposite operation for the other modes.

The switch may be better with some more resistance on pressing.It is way too light in my opinion.
I like the color indicator which shows the different states of voltage and locates the switch in the dark when the light is On.

The step down on Turbo mode is after just 3 minutes and goes directly to High mode which is more than 60% lower output.

+Compact form factor makes the TK4A easy to carry,hold,use.

The maximal brightness highly depends on the batteries,as I got different readings with the same batteries recharged several times,probably to a slightly different level.
Yet the max 1000 lumen output is a pretty good achievement.
Saying this,I have to add that the range from Turbo to High mode may be a little too much,but if the batteries are not freshly charged/new,the initial brightness will be lower,which makes the gap less noticeable.

I like that the driver shuts down the light when reaching defined low voltage level.This is a good protection for the batteries and give use safety even if we don't apply so much attention to them- LV Protection should be standard feature in every flashlight on the market. In all of the TK4A runtime tests I left the flashlight activated as long as possible and in each test,the resting voltage in any of the batteries was at least 1 volt.


Thanks for reading!
I hope you found the review helpful.

Thanks to Thorfire for providing review samples to the testers!