# Fenix TK75 Review including Extended Runtime Kits (2/4/6/8/10/12x18650 or 4/8xCR123)



## subwoofer (Feb 26, 2013)

The TK75 is Fenix’s first 2500+ lumen light to be powered by 18650s and (as far as I am aware) the first light of its type to have battery tube extensions (each holding 2 or 4 additional 18650s) for extra runtime. This special ‘extended runtime’ feature is examined in detail after the main review.

The TK75 replaces the TK70, and in its base form is significantly more compact as it runs on four 18650s rather than 4 D-cells.

_This is the fourth of a series of four detailed reviews of a selection of lights making up the ‘Totally Fenix Hunting Line-Up’. Included in the series are the TK22 (Reviewed here), TK15 S2 (Reviewed here), HL30 (Reviewed here), and this, the TK75, all of which provide a rounded set of capabilities covering everything you would need while out hunting.

Of course each of these lights stands perfectly well on their own, so this review will be covering the light in its own right, and following the individual reviews there will be a follow-up review covering the hunting applications._









Initial Impressions:

Having used the TK45 and TK41 previously, the TK75 presents itself as the grown up older brother. Arriving in the familiar plastic case, having similarly solid build quality and using the sidewinder dual switch, the TK75 just lifts the Fenix TK range to the next level.

Like the recent TK22 (reviewed earlier) the TK75 uses a stainless steel bezel giving it a serious look and more robust light head. The size of head provides a good mass of metal for heat sinking and incorporates a generous compound reflector array for the three XM-L U2 LEDs.

Fenix build quality is clearly evident with flawless fit and finish. The TK75 certainly lets you know it is a serious lighting tool.



What is in the box:

Surrounding the TK75s plastic carry case is a cardboard sleeve.






Sliding off the sleeve, reveals the single piece moulded plastic carry case which incorporates a handle.






The design uses a ‘living hinge’ to join the two halves of the case.






Included in the case are the TK75, 2 spare o-rings, a lanyard and the instructions.








Taking a closer look and looking inside:

The TK75 uses Fenix’s Sidewinder dual button electronic switch interface which places the controls comfortably under the user’s thumb.






The model, serial number and other information are laser etched into the anodised surface.






Looking into the compound reflector shows how Fenix have filled the available space with an array of good sized reflectors.






The reflectors also have a reasonable depth which provides better focusing of the beam.






The three emitters are XM-L U2 LEDs.






Threads are perfectly finished, fully anodised, lubricated and the typical trapezoid profile seen on most Fenix lights.






The tail-cap design has plenty of lanyard attachment points and provides a very stable platform for tail standing.






The TK75’s battery holder is a unique, stackable design. The main output contacts consists of a coil spring positive contact and a set of four leaf spring negative contacts






On the tail end of the battery holder is a set of contacts just like those found in the TK75’s head. These provide a connection point allowing for stacking of additional battery holders if using the extended runtime kits.






Inside the battery holder are the individual cell contacts with coil springs for negative contacts and button contacts for the positive terminals. The battery holder has a 2S2P cell configuration.






Shown here loaded with four Fenix ARB-L2 18650s.






The inside of the tail-cap has no insert and is simply a plain anodised finish.






Removing the battery tube allows a clear view of the positive and negative terminal contacts for the light head.






The TK75 breaks down into four main components, the head, battery tube, battery holder and tail-cap.






The compound reflector’s finish is excellent. The stainless steel bezel is gently crenelated.








Modes and User Interface:

The TK75 has four constant output levels and two flashing modes.

A single press of the right hand button will turn the TK75 on and off.

When on, pressing the mode switch (the left hand button) will cycle through Low, Med, High, Turbo, Low etc.

Pressing and holding the mode switch (when on) for about 1s will enter Strobe mode.

Pressing and holding the mode switch (when on) for about 3s will enter SOS mode.

If either flashing mode is being used, a single press of the mode switch returns the TK75 to a constant output mode.

The last used constant mode is remembered when switching on and off.

The TK75 has a built in automatic downshift from Turbo to High after 21minutes. To return to Turbo press the mode switch again.



Batteries and output:

The TK75 will run on 2 or 4 18650s and operates on 8.4V input voltage. The 4x18650s used for standard operation are used in 2S2P configuration. If using only 2x18650 they are in 2S configuration.

As a last resort, Fenix state the TK75 can use 4 or 8 CR123s, but doing so will force the TK75 into a single output mode.

When using just two 18650s, Turbo does work, but only for about 1-2 minutes before dropping to High.

In this section we will look at the standard configuration of the TK75, but in a special section included after the main review I will cover the TK75 with up to two extended runtime kits fitted powering the TK75 with 12x18650s (in 2S6P configuration)!

In keeping with the ‘Totally Fenix’ ethos of this series of reviews, the TK75 is being powered with Fenix ARB-L2 cells.

_To measure actual output, I built an integrating sphere. See here for more detail. The sensor registers visible light only (so Infra-Red and Ultra-Violet will not be measured)._

*Please note, all quoted lumen figures are from a DIY integrating sphere, and according to ANSI standards. Although every effort is made to give as accurate a result as possible, they should be taken as an estimate only. The results can be used to compare outputs in this review and others I have published.*


Fenix TK75I.S. measured ANSI output LumensPWM frequency (Hz)Turbo2722714Hz and 41.6kHzHigh1199181HzMedium4640Low430
 
Strobe has a dual frequency using 6.7Hz and 15.6Hz (8 flashes at each frequency)

As the TK75 utilises an electronic switch, there is parasitic drain to consider. At 58uA this is insignificant and would take over 10years to deplete a set of 4 18650s.

The runtime graph was intended to capture the maximum output capability. This meant having to constantly monitor the test as every 21 minutes it switches down to High and needs to be nudged back up to Turbo. After doing this, the following output trace is the result.








In The Lab

Introduced in Winter 2012 _ANSI standards include maximum beam range. This is the distance at which the intensity of light from an emitter falls to 0.25lux (roughly the same as the lux from a full moon). This standard refers only to the peak beam range (a one dimensional quantity), so I am expanding on this and applying the same methodology across the entire width of the beam. From this data it is possible to plot a two-dimensional ‘beam range profile’ diagram which represents the shape of the illuminated area.

In order to accurately capture this information a test rig was constructed which allows a lux meter to be positioned 1m from the lens and a series of readings to be taken at various angles out from the centre line of the beam. As the rig defines a quadrant of a circle with a radius of 1m, all the readings are taken 1m from the lens, so measuring the true spherical light intensity. The rig was designed to minimise its influence on the readings with baffles added to shield the lux meter from possible reflections off the support members.

The distance of 1m was chosen as at this distance 1lux = 1 candela and the maximum beam range is then calculated as the SQRT(Candela/0.25) for each angle of emission.

In this plot, the calculated ANSI beam ranges are plotted as if viewed from above (for some lights there may also be a side view produced) using a CAD package to give the precise 'shape' of the beam._


Starting with the 5m range grid, the TK75’s beam profile totally whitewashes the grid at this range.






Zooming out to the 50m grid, and here the TK75 is shown along with the three other Fenix lights that are part of this series of reviews, and this clearly shows how the TK75’s output totally overwhelms the others.








The beam

The indoor beamshot shows the super bright hotspot and wide spill. The spill does exhibit typical flower like shaping round the outer spill due to the compound reflector.






To show the TK75 in context, I am comparing it to the well regarded thrower the TK41. The TK41 itself is an impressive light and has been photographed here at the exact same exposure that has been used for the TK75 photograph which follows.






Now switching on the TK75 and with over three times the output of the TK41 the TK75’s performance is fantastic.








Carrying the TK75

It seemed justifiable to add a section just to look at the considerations of carrying the TK75, as unfortunately it does not come with a belt holster.

After approaching Fenix about this, I was told that the TK75 is not considered suitable for belt carry so there is no holster, nor will there be one made available.

It is not an easily ‘pocket-able’ light, well I’ve temporarily put it in the leg pocket on my cargo trousers, but you can’t really walk along with it like this.

So, what are the options? As supplied, the TK75 only has a wrist lanyard. Considering that Fenix consider the TK75 is too big to belt carry, then what about a shoulder strap? Again this is not available, so you might have to rig something up yourself.

Thanks to Martin at Torch Direct, I have been using a holster that fits the TK75.






This is actually a JETBeam RRT3 holster, but if one of the two straps is wrapped behind the holster, the Velcro strap will hold the TK75 securely.






Another less tidy alternative is a MOLLE utility/water bottle pouch or similar, such as the one I’ve got mounted on a rucksack here.







Test sample holster provided by Torch Direct for this review.



The Extended Runtime Kits

The TK75 in its standard form certainly stands tall amongst its peers, but it has one excellent feature which is unique in its class. Fenix have cleverly designed it to be expandable with battery holders that can be stacked and work in parallel. This is available in the form of the AER-TK75 Extended Runtime Kit.

As the extended runtime kits operate in parallel, working voltage is not increased, instead capacity is increased. The crucial factor here is that in using at least one extended runtime kit, the load on individual cells is significantly reduced and this allows the cells to operate more efficiently and to deliver more energy.

It is widely demonstrated that the higher the current draw from a cell, the lower the overall mAh that can be delivered, so instead of simply having a spare set of 18650s in your pocket, will preloading them in an extension kit provide real benefits in terms of overall runtime? The answer is yes, and the tests results confirm this.

For this special Extended Runtime Review section, Fenix’s maximum recommended configuration has been used. Fenix advise that only a total of three sets of batteries be used which equates to the TK75 plus 2 Extended Runtime Kits.

As this review is keeping the sample light ‘Totally Fenix’ an additional 8 ARB-L2 cells are being used.






Each of the kits consists of a battery tube extension, a stackable battery holder, and a spare o-ring.






The Extended Runtime Kits laid out.






The full set of cells, battery holders, and battery tube extensions laid out with the TK75.






Starting with the basic TK75.






Adding one Extended Runtime Kit






And then the next, bringing the TK75 up to its maximum size and weight.






So how does this overgrown light handle and how much does it weigh?

Considering there are 12 x 18650 cells now installed in this light, it is very manageable, and the result of the weigh-in is:

TK75 (with 4x18650 fitted) – 713g
TK75 plus 1 extension (with 8x18650 fitted) – 1066g
TK75 plus 2 extensions (with 12x18650 fitted) – 1418g

Three runtime tests were carried out with a matched set of cells for each battery holder to ensure the results reflect the effect of increasing the available capacity evenly as each additional set of batteries was added to the test.

Due to the TK75 automatically stepping the Turbo down to High, each test had to be monitored and the Turbo mode re-instated at each step-down.

These downshifts in output are shown clearly on the runtime graph as the sections of Turbo output.

Here you can see the superimposed runtime traces for the basic TK75 and with one and then two Extended Runtime kits.






Although the advantage of using the extended runtime kits are reasonably clear on the graph, with the overall runtime available being the most obvious gain, looking at the actual runtime logs provides the following figures:

Basic TK75:

1h02m of Turbo output
62 mins of Turbo per set of 4x18650 cells


TK75 + 1 extension:

2h20m of Turbo output (which is 2.26x the Turbo runtime compared to one set of 4 cells)
70 mins of Turbo per set of 4x18650 cells


TK75 + 2 extensions:

3h37m of Turbo output (which is 3.5x the Turbo runtime compared to one set of 4 cells)
72.3 mins of Turbo per set of 4x18650 cells

So now it becomes clear that using an extra set of cells in an extended runtime kit does not simply double the runtime, but due to the cells having a lower current draw, they are able to deliver more energy and give you a real benefit in overall runtime compared to running one set down and then swapping for the spare set.

Each battery holder can use either 2 or 4 cells, so with the extended runtime kits, you can run as many pairs of cells as you have, always gaining in efficiency the more you use. Even if you only have 6x18650 cells, using them in the 2S3P configuration will give more runtime per cell than if you use 2S2P. Each pair of cells you can add provides an advantage.

Due to the parallel connection of the stacking battery holders, you can also keep the extended runtime kit in place even if only using 4 cells. The empty battery holder simply acts like a dummy cell and provides a connection to the driver circuit.

With the extended runtime kits, the TK75 gives you enormous flexibility in size, weight, and runtime options with a maximum of 3h 37m at over 2700lm!



What it is really like to use…






The TK75 is truly a portable searchlight. The beam is primarily configured for throw and the output is regulated at 2700+lm making this a light for working at long distances. Its size, weight and massive output mean this is not something you would use for the average every-day task.

Where the TK75 comes to life is for large area lighting and long distance searching. It is a handheld light with the performance of 100-150W halogen bulb search lights normally tethered to cumbersome lead-acid 12V battery systems (or your 4x4).

Even when running the TK75 for extended periods on Turbo, it never gets excessively hot. The runtime tests were carried out with a small USB powered fan to provide some cooling and the maximum temperature recorded was 40 °C. The large head and cooling fins work effectively to dissipate the heat. In normal use and with the user’s hand also providing additional heat sinking I’ve not experienced and overheating issues.

As a lighting tool the TK75 excels. Depending on your particular requirements of runtime or size, the TK75 can be adjusted to fit. Whether checking livestock in a field, scanning for quarry (vermin or game), providing security through lighting up your property or just enjoying the incredible range of the beam, the TK75 takes it in its stride.




Test samples provided by Fenix and MyFenix for review.
Thanks go to Rob of MyFenix for helping to make this series of reviews possible.


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## subwoofer (Feb 26, 2013)

Author’s note

Normally I would not mention any of the trials and tribulations of the reviewing process, but in this instance wanted to give a little insight into why this review has taken much longer to complete than normal.

Please note: the following graphs are not representative of the true performance of the TK75 and its extended runtime kits and are only shown in context of this report on the troubleshooting carried out for the main review.

The first runtime graph initially looked reasonable if a little less Turbo runtime than expected.






But once the full set of runtime tests including the extended runtime kits had been completed, the results did not look right at all.






The set of 4 cells used for the basic TK75 runtime test had been used as the 3rd set in the final runtime test. Luckily this choice meant it was easier to determine the most likely candidate was an underperforming cell.

Faced with this spurious result set, there was no option but to check the capacity of each and every one of the 12 test cells (plus two spares thrown in for good measure) to look for the problem.

After running capacity measured discharge tests at 2A, the following set of results were obtained:

Cell No. – Capacity in mAh
1 -2514
2 -2512
3 -2190
4 -2517
5 -2507
6 -2441
7 -2462
8 -2503
9 -2483
10-2485
11-2473
12-2495
13-2516
14-2546

Cells 13 and 14 were two additional ARB-L2 cells from the TK15 and TK22 reviews.

As can be seen, cell 3 was giving a lower result, and bearing in mind the series pairs of cells, this low capacity would reduce the effective capacity of its paired cell as well.

Having identified the culprit, cell 3 was substituted with cell 13, and the entire set of monitored runtime tests was re-run to provide the good results shown in the main review.

With the re-runs of the runtime tests, this review has taken a loooong time to produce, time which needs to be fitted in around a full time job and a wife!

Some people may call me mad – I’m beginning to think they are right.


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## Davekan (Feb 26, 2013)

Very nice read. Thanks for that. Nice shots.


Dave


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## Patriot (Feb 26, 2013)

Outstanding review! I can sympathize with the type of trouble shooting you had to deal with. Still you brought us another informative report and we appreciate your work.


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## kj2 (Feb 27, 2013)

Thanks for the review  and that holster is a good idea. Maybe I buy one for my TK75.


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## newbie66 (Mar 2, 2013)

I am quite new to flashlights and this is my first post as a new member.

So my thoughts on this light is that the light is still quite expensive to buy especially when one has to also purchase at least 4 18650s'. I definitely can't afford it, and won't be owning one. But nonetheless I still enjoy other people's reviews or comments.


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## daBear (Mar 3, 2013)

I just ordered a TK75, Fenix charger, 8 Fenix batts, and the extension kit, no tax and delivered for just under $300. I think I got a pretty good deal and this will be my first high powered LED light. I am an old incan fan and this might turn me.


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## subwoofer (Mar 4, 2013)

daBear said:


> I just ordered a TK75, Fenix charger, 8 Fenix batts, and the extension kit, no tax and delivered for just under $300. I think I got a pretty good deal and this will be my first high powered LED light. I am an old incan fan and this might turn me.



Sounds like a fantastic deal to me, and I think you will be blown away once you fire it up. Let us know how you get on.


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## hikingman (Mar 4, 2013)

Great review and I love this light - EXCEPT, for me, it's one great failing. IT IS waayyyyyy too easy to turn on and requires 2 and a quarter turns of the body (at least) to lock it out. When I look at your picture of the holster, I can't help feeling a light slap to the side of it and that light is coming on! It's hard to tell but can you REALLY carry it around in that holster without the light coming on?

Dave


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## subwoofer (Mar 4, 2013)

hikingman said:


> Great review and I love this light - EXCEPT, for me, it's one great failing. IT IS waayyyyyy too easy to turn on and requires 2 and a quarter turns of the body (at least) to lock it out. When I look at your picture of the holster, I can't help feeling a light slap to the side of it and that light is coming on! It's hard to tell but can you REALLY carry it around in that holster without the light coming on?
> 
> Dave



Do you have one? I ask as you seem very sure about the ease of accidental switch on.

The power switch does need a firm press to operate it, and you can always leave it on low so even if it does turn on it should be low.

In that holster, if you fit it in with the switch facing into the holster it is completely protected from being accidentally pressed, so the holster does work well.


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## brightnorm (Mar 4, 2013)

hikingman said:


> Great review and I love this light - EXCEPT, for me, it's one great failing. IT IS waayyyyyy too easy to turn on and requires 2 and a quarter turns of the body (at least) to lock it out....Dave



Clearly, the light is too easily accidentally activated. I solved this by using stick-on Velcro to build a raised surround which protects the switch while retaining functionality. IMO, Fenix should have built in similar protection.

Brightnorm


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## hikingman (Mar 4, 2013)

subwoofer said:


> Do you have one? I ask as you seem very sure about the ease of accidental switch on.
> 
> The power switch does need a firm press to operate it, and you can always leave it on low so even if it does turn on it should be low.
> 
> In that holster, if you fit it in with the switch facing into the holster it is completely protected from being accidentally pressed, so the holster does work well.




Yes I do have one and how firm a button press is _is_ something next to impossible to convey. The only other light I have with a _very_ easy press is Olight's SR95. My TK75, of course, could be abnormal, but I find it very easy to switch on. I have a pouch for it and when I put light and pouch into a small pack for walking, it has turned on twice out of a half dozen trips. So I do, as you say, and always leave it on low before switching off. I tried Brightnorms method already and it is a good idea. I think my solution is too thick which sort of creates a "well" where the buttons are


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## daBear (Mar 4, 2013)

Well I just got my TK75 and I love it already and it hasn't even gotten dark. The only complaint I have is it kicks so hard when you turn it on.


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## herosemblem (Mar 4, 2013)

daBear, what do you mean the light "kicks so hard when you turn it on"?


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## daBear (Mar 5, 2013)

herosemblem said:


> daBear, what do you mean the light "kicks so hard when you turn it on"?



The light is so strong it kicks when you turn in on. 

(might be a little exaggeration)


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## subwoofer (Mar 5, 2013)

hikingman said:


> Yes I do have one and how firm a button press is _is_ something next to impossible to convey. The only other light I have with a _very_ easy press is Olight's SR95. My TK75, of course, could be abnormal, but I find it very easy to switch on. I have a pouch for it and when I put light and pouch into a small pack for walking, it has turned on twice out of a half dozen trips. So I do, as you say, and always leave it on low before switching off. I tried Brightnorms method already and it is a good idea. I think my solution is too thick which sort of creates a "well" where the buttons are



Agreed, the feel of a button is difficult to describe in words.

It would be better if there was a choice of lock-out or switch protection, as even though I've yet to experience an accidental activation, I can see the possibility.



herosemblem said:


> daBear, what do you mean the light "kicks so hard when you turn it on"?



I'm curious too. A recoiling light?


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## TEEJ (Mar 5, 2013)

The "recoil" of the light was an attempt at humor.

He was obviously trying to imply (A joke) that the light is so powerful that the light being sent out caused the flashlight to be pushed backwards (An equal and opposite reaction, etc...).


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## subwoofer (Mar 5, 2013)

TEEJ said:


> The "recoil" of the light was an attempt at humor.



I know  I was just imagining a light that you need to brace yourself against its recoil prior to switching it on.

As I believe photons do have mass, there will indeed be some recoil and the light will actually act like a very very weak rocket engine (any physicists able to quantify this?), but you would never be able to feel this effect.


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## daBear (Mar 5, 2013)

You fellows crack me up. I am an old incan light builder and we have some 100 watt ++ lights with some real kick when you turn them on. I built some LED lights several years ago and they just didn't get the job done like an incan. That was then and this is now. All I can say about the TK75 is wow. This is my new favorite light. Even thought it won't burn a hole in anything like a good incan will. 

I was draining the batteries on a 100 watt incan one time and left it in a chair and went in another room. When I came back the cloth on the chair had melted and I was the proud owner of a 3 inch hole in an expensive chair. That cost me several hundred dollars for my wife to buy a new chair not to mention the knots she put on my head. At least I don't have that to worry about with the new LED lights. They get hot, but not that hot.

Now, y'all loosen up a bit and enjoy the kick of the high power lights.


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## subwoofer (Mar 5, 2013)

daBear said:


> You fellows crack me up. I am an old incan light builder and we have some 100 watt ++ lights with some real kick when you turn them on.



Although digressing somewhat, was the kick of the old incan monsters actually from the massive relays needed to switch the required current on and off, rather than anything else?


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## daBear (Mar 5, 2013)

The old incan's didn't really kick but they were a hoot to turn on in a crowd. I would take a 3D Mag conversion fame thrower and turn it on then tell the onlookers it was a new MagLite from WAL-Mart. Go get you one.


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## 3liminate (Jul 29, 2013)

Excellent Review.
Thanks for your troubles - much appreciated 
Over 2700 Lumens - WOW!


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## holylight (Jul 31, 2013)

*Fenix TK75 Review including Extended Runtime Kits (2/4/6/8/10/12x18650 or 4/8xC*

Thanks for the review.


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## Capolini (Aug 9, 2013)

I am sooooo excited :wave::wave:, I just had to post!! Forgive me. I am new and probably should have started a new post!! However, this is related to your review!!

I just ordered the NEW TK-75[TK75-L2BK]!!! The XM-L2 [U2]Cree LED supposedly will make it 300 lumens brighter, 27,500 extra candelas and 84 more meters of throw! I have the original and am confident that this will live up to the Fenix quality! Fenix outfitters just got them! I was there first order,should have it Monday or Tuesday,,I live in Suburban Philly,,,my Siberian Husky will love it!! lol

I can't stop!! I am a "Flashaholic" with Twelve [12] lights in only 7 months of collecting!!

I look forward to your review of it!! 

Feedback is appreciated!! If anyone else gets one soon let me know how you rate it!

ciao,,,,Roberto,,"Capo di Capo":wave:


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## subwoofer (Aug 11, 2013)

Capolini said:


> I am sooooo excited :wave::wave:, I just had to post!! Forgive me. I am new and probably should have started a new post!! However, this is related to your review!!
> 
> I just ordered the NEW TK-75[TK75-L2BK]!!! The XM-L2 [U2]Cree LED supposedly will make it 300 lumens brighter, 27,500 extra candelas and 84 more meters of throw! I have the original and am confident that this will live up to the Fenix quality! Fenix outfitters just got them! I was there first order,should have it Monday or Tuesday,,I live in Suburban Philly,,,my Siberian Husky will love it!! lol
> 
> ...




Nice! The TK75 will truly sing with XM-L2s - good choice.


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## Capolini (Aug 11, 2013)

subwoofer said:


> Nice! The TK75 will truly sing with XM-L2s - good choice.



Thanks!!! I forgot to add that I got it for $179.00 w/ promo code! I paid $209.00 for my original!

So, how is the weather there in good old U.K.?!! :thumbsup:


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## Capolini (Aug 11, 2013)

subwoofer said:


> Nice! The TK75 will truly sing with XM-L2s - good choice.




WOW!!!! I just saw all the reviews you have done!! That takes a lot of time, research and dedication! I was wondering, do you guys get any compensation for doing them? If not, where do you find the time??!! They are also very thorough.

ciao,,Roberto,"Capo di Capo"   :twothumbs


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## BLUE LED (Aug 11, 2013)

Does anyone know if the new TK75 uses a XM-L2 U2 or XM-L2 T6.

Also does it now have a lock-out facility? 

The weather in London is sunny with a cool breeze.


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## Capolini (Aug 11, 2013)

BLUE LED said:


> Does anyone know if the new TK75 uses a XM-L2 U2 or XM-L2 T6.
> 
> Also does it now have a lock-out facility?
> 
> The weather in London is sunny with a cool breeze.



XM-L2 [U2]  No lockout :shrug:

Ciao Roberto,"Capo di Capo",,,,,,,,sunny and 84F IN Philly!


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## martinaee (Aug 11, 2013)

So would this work on my scooter?

Would this work well on my tricycle? 

Is it brighter than my maglite?

Is this light brighter than my 100 - 5mm led light?

Is this light bright?



>>>>> LOL (joking... some of you may get what thread I'm referencing with this...)


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## Capolini (Aug 11, 2013)

martinaee said:


> So would this work on my scooter?
> 
> Would this work well on my tricycle?
> 
> ...




Answers: NO, NO, YES, YES AND YES!!!! Please that gentleman was toooooooooo much to handle! lol,lol,,,,,,:mecry::laughing::shakehead


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## mmjsport (Aug 14, 2013)

I've been looking for a review like this for a while with the extra run time kits. Thanks a lot for taking your time and doing it right. :thumbsup:


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## jhovan (Sep 20, 2013)

What are your thoughts on using this light inside a backpack while running? Is the light built to withstand constant jarring? Or, do you think it would shorten the lifespan?


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## subwoofer (Sep 23, 2013)

jhovan said:


> What are your thoughts on using this light inside a backpack while running? Is the light built to withstand constant jarring? Or, do you think it would shorten the lifespan?



Used without the extensions, the TK75 is very solid. The one I have does not rattle at all when shaken, however if you bang it, it does have a bit of spring-ring and signs of the batteries moving about a bit.

This is part of the Fenix TK (Tank) range so should be up to quite a lot of knocking about. In fact it is often the batteries which suffer the most from any jarring rather than the light.

The TK75 does not have any real lockout (you have to unscrew the tailcap until it is almost off), so if it is bouncing about in a backpack, it might come on. If packed carefully it should be fine.

If you knock about any light its life will be shortened. This can be due primarily due to contacts or switches suffering wear (the LED should be unaffected).


What are you actual requirements for a light and how will you use it (apart from carrying it in a backpack)?


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## csfirearms (Sep 27, 2013)

Just a question on your review. I just bought the TK75 and the extra extensions and was wondering if it can run on low for over eight days, how long does it last with the two extensions added to it? Any info would be great. Thanks!!

CSF


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## subwoofer (Sep 29, 2013)

csfirearms said:


> Just a question on your review. I just bought the TK75 and the extra extensions and was wondering if it can run on low for over eight days, how long does it last with the two extensions added to it? Any info would be great. Thanks!!
> 
> CSF



Li-ions, and in fact any cell, becomes less efficient as the current draw increases due to the internal resistance. The main gain in efficiency with the extension tubes is when there is a high current draw. Adding the first extension (2 battery carriers/8 cells in total) effectively halves the current draw from each cell and allows for each cell to work more comfortably and provide longer combined runtimes.

When the current draw is much lower (when using the low mode) there will be little gain in efficiency, so in this instance the total runtime will be much the same as a simple multiple of the runtime for a single set of cells. As specified by Fenix, the low runtime is 200 hours, so with one extension added you get 400 hours and with two added you should get 600 hours. Not the same gains as when running on Turbo, but a single light with extremely long runtime.


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## blerkoid (Oct 2, 2013)

Hello CPF!

I just got my TK75 today and I took it for a little walk. After a few minutes I noticed a little condensation(?) on the inside of the lens, near the middle. Is this normal for anyone else out there? The temperature tonight was about 5 degrees celsius. I can provide pictures if this does not make sense.

The actual light was mindblowing and the distance it covered was amazing! The only other light I have to compare it to was the SRT7 and it easily blew it out of the water. Not a fair comparison, but it was all I had to work with.
The weight was minimal. I could easily walk the dog and hold the light without any discomfort.

Hopefully the lens fogging up is not a big issue, but I had to ask.

Thanks in advance!


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## blah9 (Oct 2, 2013)

I'm glad you like it! Take a look here for information about the fogging issue: http://www.candlepowerforums.com/vb...5-quot-Condensation-Fog-under-lens-again-quot. Some people have had success in getting rid of the fog.


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## subwoofer (Oct 3, 2013)

blerkoid said:


> Hello CPF!
> 
> I just got my TK75 today and I took it for a little walk. After a few minutes I noticed a little condensation(?) on the inside of the lens, near the middle. Is this normal for anyone else out there? The temperature tonight was about 5 degrees celsius. I can provide pictures if this does not make sense.
> 
> ...



As pointed out by blah9, the fogging issue has been discussed in depth in another thread.



blah9 said:


> I'm glad you like it! Take a look here for information about the fogging issue: http://www.candlepowerforums.com/vb...5-quot-Condensation-Fog-under-lens-again-quot. Some people have had success in getting rid of the fog.



I would add to this, that the TK75 has a large area of glass and a relatively large volume of space inside it to harbour humid air (and therefore the potential for fogging). You do need to take care not to introduce moisture into the light's body as it will get into the head.


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## CaptainRogersUK (Oct 3, 2013)

weather crap tonight in the uk, heavy rain.... seriously thinking of ordering this with two extender packs but cant justify the amount of money it is right now, just waiting for a custom/mod TN31 off Vinyh so cant really justify exense of this right now, unless I sell my kidney.. lol


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## cheaperrooter (Nov 25, 2013)

Just got it. Be here in two days. B&H Photo for $169.99 free shipping (yes, the 2900 version)


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## subwoofer (Nov 26, 2013)

cheaperrooter said:


> Just got it. Be here in two days. B&H Photo for $169.99 free shipping (yes, the 2900 version)



B&H prices can be very good, they have even been good enough to get things shipped to the UK (photographic equipment rather than lights).

Hope you have a couple of sets of good quality 18650s charged and ready to go ;-)


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## Lightning Bub (Dec 5, 2013)

cheaperrooter said:


> Just got it. Be here in two days. B&H Photo for $169.99 free shipping (yes, the 2900 version)



I just ordered mine from B&H as well, along with two of their extended runtime kits (which they state include batteries, but I doubt it). I also picked up 12 3400mah 18650s and a nitecore charger from Amazon. All told, I am out about $300, but I have the bug now. I picked up a couple cheap lights recently, and now I am hooked. 

Thanks for this awesome review!


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## Lightning Bub (Dec 7, 2013)

The Fenix website and packaging for the runtime kits state "The use of more than three kits in one TK75 flashlight is not recommended", so I am confused as to whether or not they are considering the single tube that comes with the flashlight as a "kit".


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## Lightning Bub (Dec 11, 2013)

blerkoid said:


> Hello CPF!
> 
> I just got my TK75 today and I took it for a little walk. After a few minutes I noticed a little condensation(?) on the inside of the lens, near the middle. Is this normal for anyone else out there? The temperature tonight was about 5 degrees celsius. I can provide pictures if this does not make sense.
> 
> ...



Mine gets a small condensation spot as well. It is right in the center of the lens and about the size of a dime. It shows up when the head is hot and goes away when it cools off. I am wondering how moisture could have gotten in there.


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## subwoofer (Dec 11, 2013)

Lightning Bub said:


> The Fenix website and packaging for the runtime kits state "The use of more than three kits in one TK75 flashlight is not recommended", so I am confused as to whether or not they are considering the single tube that comes with the flashlight as a "kit".



Having added two extensions (so having three battery holders in use), the tail-cap does not screw on as far. I would not want to add a third extension (fourth battery holder), so feel that their intention was to mean using no more than three battery holders (or the TK75 plus two extensions). IMHO.



Lightning Bub said:


> Mine gets a small condensation spot as well. It is right in the center of the lens and about the size of a dime. It shows up when the head is hot and goes away when it cools off. I am wondering how moisture could have gotten in there.



The head is not sealed, so any moisture entering the batter tube (and being sealed inside when re-fitting the tail-cap), can make its way into the head by diffusion - just as with most lights.


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## Lightning Bub (Dec 11, 2013)

subwoofer said:


> Having added two extensions (so having three battery holders in use), the tail-cap does not screw on as far. I would not want to add a third extension (fourth battery holder), so feel that their intention was to mean using no more than three battery holders (or the TK75 plus two extensions). IMHO.
> 
> 
> The head is not sealed, so any moisture entering the batter tube (and being sealed inside when re-fitting the tail-cap), can make its way into the head by diffusion - just as with most lights.



Thanks for the info. I went with two extension tubes and glad I did. I can get the tail cap to screw all the way down, but it is not easy and put a pretty decent rub ring on the inside of the tail cap. 

Our weather has been a bit moist as of late. I will throw it in a box with a buch of dessicant packs to see if that removes the moisture.


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## AA#5 (Dec 11, 2013)

BLUE LED said:


> Does anyone know if the new TK75 uses a XM-L2 U2 or XM-L2 T6.
> 
> Also does it now have a lock-out facility?
> 
> The weather in London is sunny with a cool breeze.



The manual with mine says, "Unscrew the tailcap 1/2 turn or take out the battery to prevent accidental activation during storage or transport." After trying that, I found that the manual should have said, "Unscrew the tailcap TWO OR THREE TURNS."


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## AbbyY (Dec 12, 2013)

Thanks a lot for review subwoofer!

Based on your runtime tests I've got it (L2 version/2.900 lumens) + 2 extender kits (12xNCR18650B Panasonic). It fits perfectly in my Niwalker BK-FA01/02 holsters:












And a comparison with SR95S UT, RC40 and SR96:


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## NorthernStar (Dec 12, 2013)

Great review with nice pics!

Now i have a TK75-L2 incoming, and i have some questions about the light. It did not include any holster(like you mentioned) so i am going to carry it either in the pocket of my parkas or in my backpack. Since it has no lockout mode i wonder if accidental activation happens easy on this light? This question is subjective, but is it comfortable to carry the light with one extension kit attached to it over a longer time?


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## blah9 (Dec 12, 2013)

If I were you I would definitely lock the light out at the tailcap if it is in a backpack. I thought it would be okay to leave it on low mode and then turn it off to put it in a backpack since then if it did turn on it would only be in low mode. But then at an airport it turned on by itself in my bag and became very hot. It turned out that it even got switched into a higher mode. I could not easily touch the light because it was so hot, so I turned it off and unscrewed it with a buffer layer between my hands and the light. Be careful!


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## AbbyY (Dec 13, 2013)

Is it ok to use unprotected cells? If I am not wrong, unprotected cells have a higher drain capacity and I think TK75 is suitable for using them. I have both protected and unprotected Panasonic NCR18650B rechargeables and I would like to use unprocteded ones too.


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## NorthernStar (Dec 13, 2013)

blah9 said:


> If I were you I would definitely lock the light out at the tailcap if it is in a backpack. I thought it would be okay to leave it on low mode and then turn it off to put it in a backpack since then if it did turn on it would only be in low mode. But then at an airport it turned on by itself in my bag and became very hot. It turned out that it even got switched into a higher mode. I could not easily touch the light because it was so hot, so I turned it off and unscrewed it with a buffer layer between my hands and the light. Be careful!



Thank´s for the advice!

Well,then i will etiher lock it out by unscrewing the tailcap, or like mentioned earlier in the thread one can wrap a stick on velcro around the buttons to prevent accidental activation.


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## Lightning Bub (Dec 14, 2013)

I use unprotected NCR18650B 3400 mah cells in mine (12 of them) and have had no issues. 

Sent from my SCH-I605 using Tapatalk


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## Visna (Dec 20, 2013)

Hi all,
are there any problems with switches like on tk41 ??? they looks similar


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## AbbyY (Dec 20, 2013)

Lightning Bub said:


> I use unprotected NCR18650B 3400 mah cells in mine (12 of them) and have had no issues.
> 
> Sent from my SCH-I605 using Tapatalk



Thanks! I also used unprotected 12xNCR18650B 3400 mAh and I've had no problem yet.


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## gigahertz (Dec 29, 2013)

I have a question about the TK-75.

I want to buy an extension tube for my TK-75 and I am wondering if I should or have to use batteries of the same exact model/capacity for the extension tube.

Currently I am using the Fenix batteries that came with my TK-75 and would like to get some 3400mah Panasonic for the extension tube if it's ok to mix the two battery types.

Thanks!


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## AbbyY (Dec 29, 2013)

You have to use the same capacity batteries and the same model/manufacturer. It is also strongly recommended that all batteries must be balanced (the same batch, the same number of charging/discharging cycles). These are condition for using batteries in multiple configuration.


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## thedoc007 (Dec 29, 2013)

gigahertz said:


> I want to buy an extension tube for my TK-75 and I am wondering if I should or have to use batteries of the same exact model/capacity for the extension tube.
> 
> Currently I am using the Fenix batteries that came with my TK-75 and would like to get some 3400mah Panasonic for the extension tube if it's ok to mix the two battery types.



I know it stings, but as AbbyY said, you really should use batteries from same batch/capacity/manufacturer. Better to order a whole new set of 3400s when you order the extension tube (eight of them if you buy one tube). You can either keep the original four 2600s as spares, or sell them on CPFMP, or use them in other lights. Mixing cells is a bad idea - those warnings are there for a reason, and people have found out the hard way that lithium cells can fail spectacularly if they are mismatched. Learn from the mistakes of others, and stay safe!


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## subwoofer (Dec 29, 2013)

gigahertz said:


> I have a question about the TK-75.
> 
> I want to buy an extension tube for my TK-75 and I am wondering if I should or have to use batteries of the same exact model/capacity for the extension tube.
> 
> ...





AbbyY said:


> You have to use the same capacity batteries and the same model/manufacturer. It is also strongly recommended that all batteries must be balanced (the same batch, the same number of charging/discharging cycles). These are condition for using batteries in multiple configuration.





thedoc007 said:


> I know it stings, but as AbbyY said, you really should use batteries from same batch/capacity/manufacturer. Better to order a whole new set of 3400s when you order the extension tube (eight of them if you buy one tube). You can either keep the original four 2600s as spares, or sell them on CPFMP, or use them in other lights. Mixing cells is a bad idea - those warnings are there for a reason, and people have found out the hard way that lithium cells can fail spectacularly if they are mismatched. Learn from the mistakes of others, and stay safe!



I'm going to be controversial here and contradict the previous two posts.

The TK75's battery carrier uses 2S2P configuration which gives the 8.4V working voltage. If you add a second you still have 8.4V as the second carrier is also 2S2P, and is connected in parallel by the TK75's contact design.

Now the effect of this is that combined the cells are get 2S4P (remember that the total number of cells for XSYP = X x Y, so 2S2P has 2x2 or 4 cells and 2S4P has 2x4 or 8 cells).

The reason for talking about this is to reinforce the most important principles when combining cells.

If using cells in series, it is very important that they are as well matched as possible in capacity, charge level and that they are protected.

However, when using cells in parallel, this capacity matching is far far less important. In fact the only really important factor when using cells in parallel is matching the charge level. (Note that cell age can affect its ability to hold full charge, so cells should be similar in age - and age refers not just to calendar age, but to cycles as well).

When you have cells working in parallel (or even batteries - being a collection of cells), each individual cell will work together with the others, and if one cell is weaker, the others will simply work a bit harder. All the cells are linked in voltage, so it will be the strongest cell that works hardest. If you have one 2600mAh cell with one 3400mAh cell connected in parallel, during use, the 3400mAh cell would normally maintain its voltage better than the 2600mAh cell, but when working in parallel, as the load causes the voltage of the two cells to drop, the stronger cell will take the load off the weaker one but the cell voltages will stay the same.

So take this to the TK75's configuration...

The TK75 can run on 2 cells as long as you install these in 2S1P configuration (one cell with +ve facing towards the LED and one towards the tailcap). These cells are one 2S1P 'battery' and need to be closely matched.

Theoretically, you could now use 2 matched cells of a different capacity to make up the second 'P' part (to make it 2S2P), however it is far easier to avoid mistakes, by using a set of 4 matched cells in the TK75's battery carrier.

That is one battery carrier, so when moving onto a second one (which will be connected in parallel), the theory of using cells in parallel comes into effect. So if you have a second set of 4 matched cells that you can keep together in the second battery carrier, this will then be working in parallel with the first battery carrier so the actual cell capacity is not important, only the level of charge matters.


So despite the overstated paranoia regarding li-ions on CPF, given a bit of logical thought, I personally would be happy to use the cells as you described with 4x2600mAh in one carrier and 4x3400mAh cells in the second. I am happy to do this ONLY because they are used in parallel, if the combination of battery carriers was in series, I would not consider this safe.

Before doing this I would ensure all cells are charged to the same state of charge (measure the resting voltage of the fully charge cells), and each set is kept together and never mixed between the carriers.


Yes, ideally, in an ideal world, and one in which money is no object then get 8 new matching cells, but in the real world where money is a consideration, as long as you think about what you are doing, you don't need to buy 8 new cells, the four you are thinking of will be fine if used as I have described.


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## gigahertz (Dec 29, 2013)

AbbyY said:


> You have to use the same capacity batteries and the same model/manufacturer. It is also strongly recommended that all batteries must be balanced (the same batch, the same number of charging/discharging cycles). These are condition for using batteries in multiple configuration.






thedoc007 said:


> I know it stings, but as AbbyY said, you really should use batteries from same batch/capacity/manufacturer. Better to order a whole new set of 3400s when you order the extension tube (eight of them if you buy one tube). You can either keep the original four 2600s as spares, or sell them on CPFMP, or use them in other lights. Mixing cells is a bad idea - those warnings are there for a reason, and people have found out the hard way that lithium cells can fail spectacularly if they are mismatched. Learn from the mistakes of others, and stay safe!



Thanks for your replies. The horror stories I read here about these cells going boom had stopped me from getting anything with lithium rechargeable.

That was until the TK75 was introduced, I love this light


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## gigahertz (Dec 29, 2013)

subwoofer said:


> I'm going to be controversial here and contradict the previous two posts.
> 
> The TK75's battery carrier uses 2S2P configuration which gives the 8.4V working voltage. If you add a second you still have 8.4V as the second carrier is also 2S2P, and is connected in parallel by the TK75's contact design.
> 
> ...



Thanks for taking the time to post such a detailed well explained reply. You reasoning make sense as that's how I understood in general how batteries in parallel arrangements work.

I will take your advice and order up some new batteries for my TK75 ext tube.

Cheers!


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## tedscossie (Jan 2, 2014)

Hi there,
very nice and interesting review with nice pics!
I am very interesting in buying this torch because it has a good price concerning his lumens and abilities!
I look forward to have one in my hands!

Ted


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## Goredoth (Mar 28, 2014)

Thanks for the review really detailed I was really interested in the extender kits so appreciate you going the extra mile and doing that for us!


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## Richwouldnt (May 12, 2014)

I just ordered the TK75 Cree XM-L2 version and one extender. One thing that amazed me when reading the review of the light here is that a light weighing only a bit over one pound w/o batteries, and putting out 2900 Lumens, can run continuously in Turbo mode without suffering damage or melt down. LEDs must be getting considerably more efficient than several years ago or Fenix has done an outstanding job of heat sinking the LED to dissipate the heat and prevent heat buildup. To me the reasonable weight combined with the extremely high light output and the extended run time at maximum output allowed by the battery extenders makes this light the current champion of combined output and practicality for a high output torch.

I remember when the SR90 came out and the excitement at the time. It looks to me like this is about 1/2 the weight, has almost 50% more output and handles the heat of maximum output continuous operation better than the much more massive Olight ever did. Isn't progress great!


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## 1uke (Dec 14, 2014)

I just received this torch and it's a total beast! I now have to get a good holster as with the battery extender and extra batteries it weighs quite alot. I had it on turbo mode for around 30 minutes and it certainly heated up but not to any extent that I couldn't touch any part of the light. I'm very happy and I didn't realise the range until I got into the open.


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## subwoofer (Dec 15, 2014)

1uke said:


> I just received this torch and it's a total beast! I now have to get a good holster as with the battery extender and extra batteries it weighs quite alot. I had it on turbo mode for around 30 minutes and it certainly heated up but not to any extent that I couldn't touch any part of the light. I'm very happy and I didn't realise the range until I got into the open.



You are going to love this light.

I'm constantly torn between using the extenders and not. Without it is very carryable. With one it becomes more of a burden, but you get all that runtime. With two extenders...well it has to be a special occasion.

I've fallen into a routine of when it is in the house it has one extender on it. If I'm going out with it, frequently the extender comes off (but the battery carrier it taken loaded with cells ready to swap out).


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## theOS (Nov 10, 2015)

Hi!
I must say i am kind of disappointed by Fenix ARB-L2 batteries on my fenix tk75 (2009lm version) on turbo mode they last only 28 min.
I have test them on a Tk75 2600 lm version and they last a little longer ... 38 min on turbo mode (accumulated time)
*B*atteries only used 4-5 months, i really think other brands are doing better. 
I have contacted Fénix Spain customer support and they are totally useless.


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## BLUE LED (Nov 10, 2015)

theOS said:


> Hi!
> I must say i am kind of disappointed by Fenix ARB-L2 batteries on my fenix tk75 (2009lm version) on turbo mode they last only 28 min.
> I have test them on a Tk75 2600 lm version and they last a little longer ... 38 min on turbo mode (accumulated time)
> *B*atteries only used 4-5 months, i really think other brands are doing better.
> I have contacted Fénix Spain customer support and they are totally useless.



It's not the battery at fault. It is the different versions on TK75 that you have. The timed step down on the original TK75 XM-L U2 is around 20 mins. Accumulated turbo time is around 40 minutes.

This was reduced to around 15 minutes on the 2nd version TK75 XM-L2 U2 2900 Lumens. Accumulated time on turbo around 30 minutes. 

Instead of buying 2 versions I just moded my 1st gen TK75 2600 Lumens with 3 x XM-L2 U4. My accumulated time on turbo is 44 minutes.


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## subwoofer (Nov 10, 2015)

theOS said:


> Hi!
> I must say i am kind of disappointed by Fenix ARB-L2 batteries on my fenix tk75 (2009lm version) on turbo mode they last only 28 min.
> I have test them on a Tk75 2600 lm version and they last a little longer ... 38 min on turbo mode (accumulated time)
> *B*atteries only used 4-5 months, i really think other brands are doing better.
> I have contacted Fénix Spain customer support and they are totally useless.




As well as the answer BLUE LED has given, I would also point out that the way any cells are used affects their lifespan. Li-ion like to work in the 30-90% charge level range. If you keep them at 100% or regularly deep discharge them to below 30%, and especially if you leave them fully discharged, you increase the rate they degrade. Add to this a lot of cycles and you can 'wear out' any cells very fast.

If you hit the cell protection regularly, you should expect your cells to not last as long, and if you do, you should get them on charge asap to at least get them partially charged.

High drain also increases cell wear, so always using Turbo will also be harder on your cells.

There are many factors affecting cell life, and the typically quoted 'rechargeable for 500 cycles' does not take into account certain cell ageing factors.

Without knowing exactly how each cell has been treated, it is impossible to say if there is a cell related issue.


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## theOS (Nov 10, 2015)

The batteries were always charged/used only with Fenix products (ARE-C2/TK75) , most of the times put to charge at 3.7 - 3.8 V remaining power.
I find this kind of disappointing due to the fact they only reach an autonomy of 37% from what Fenix promise.
Anyways i also had Panasonic batteries and they performed better than Fenix.


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## BLUE LED (Nov 13, 2015)

I prefer Eagletac 3,500mAh and Nitecore D4 charger. It always charges to 4.20v

Good quality cells and charger.


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