# Fenix TK21 U2 user interface problems



## msm1018 (May 6, 2011)

So I had been wanting a new powerful LED flashlight for a toy and I came upon the TK21. I thought what a great compromise of size and output. I ordered one with four new tenergy 18650's and waited impatiently for about 5 days. I finally got it in the mail and tested it out that night only to find out that the turbo mode only stays there for about five to ten seconds and steps down to high. I am devistated by this problem because I was excited to have a new flashlight. I sent it back for a different one and hope that when I get the new one it will be normal. I hope this isn't a manufacturing defect. Anyone else out there experiencing problems with their's? By the way the light itself was awesome, my brightest one by far! I cannot wait for the replacement to come.


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## Hitthespot (May 6, 2011)

Actually mine did this with only one of my two Tenergy batteries. IF you have this problem with the new light, I would check to make sure it happens with more than one battery. Then check it with CR123's. You may find you have a battery problem not a flashlight problem.

Bill


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## msm1018 (May 6, 2011)

I did try it with other batteries and it did the same thing. I tried cleaning all the contacts flashlight and batteries to no avail.


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## msm1018 (May 6, 2011)

I'll be sure to be thorough with the new light too. If it does happen to be the batteries I hope rcr123a bats work. I hate the thought of using non-rechagables in that light.


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## chipdouglas (May 9, 2011)

Has anyone else noticed the issue the OP has brought up ?


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## newless (May 9, 2011)

chipdouglas said:


> Has anyone else noticed the issue the OP has brought up ?


 
I have a TK21 and use Tenergy Rcr123's, I haven't notice this issue.


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## quad088 (May 10, 2011)

I am about to make purchase of TK21 next week, after reading this tread I better check before I get one


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## scotto (May 10, 2011)

My TK21 arrived today and I do not have this issue using 2 brand new CR123a's. My order of 18650's hasn't arrived yet so can't give you and info on the rechargeable front though however.

By the way... very nice light!! I'm like a kid in a candy shop with this new toy. Will be my EDC light along with an E05 from tomorrow!!


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## PCS (May 10, 2011)

chipdouglas said:


> Has anyone else noticed the issue the OP has brought up ?


 No problems here with two Duracell CR123A's. I suspect the OP just got a problem light.


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## wrf (May 10, 2011)

chipdouglas said:


> Has anyone else noticed the issue the OP has brought up ?


 
Yes.

I have two TK21 lights in very limited use. The first has not shown the behavior mentioned (neither on Surefire 2xCR123A nor Redilast 2900 mah 18650). The second light shows the behavior (erratically) when using the 18650, but I did not experience it during the short time it was run on 2xCR123A. The battery in the second light was actually run previously in the first light. When I moved the battery I attempted to top it off in a Pila charger, but the charger indicated already full and no addtional charge was applied. I did not have a voltmeter handy and did not measure battery voltage.

These are all preliminary observations. I have not used the lights enough to come to conclusions of any certainty, nor have I checked and cross-checked any test cases. At the moment I have other fish to fry, and am not very concerned with this particular issue.


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## Midnight_Flasher (May 17, 2011)

Could it be just that draw is too high for some cells? This is shame, since I was going to grap this light. Has OP something new to tell to those who are now in doubt?


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## ManChow (May 17, 2011)

TK21 is one of my favorite XML based tatical flashlight, it no doubt is the king of XML single cell (1x18650/17670/2xCR123) tatical, no matter when it's compare with other same class of product. 







For the issue you mentioned, this is caused by an IC performance matter, Fenix was addressed the problem and trace that just a little bit of TK21 were equipped with those substandard IC's in first batch of the stock and shipped. So please don't worry, you just only need to swap a new one without the problem from the supplier that is ok, Fenix also have the excellence after sales service.

Cheers,


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## msm1018 (May 17, 2011)

I sent back the light to the retailer and they deemed it 100% functional. They were nice enough to ship it back with an ultrafire 18650. That battery did the same thing as the tenergys I bought with the light. I did however go to my local sporting goods store and paid way too much for 2 surefire batteries. I have checked the light with the primaries and it has not done it with them in it. It only seems to be with the Li-ions. Kind of makes me mad because I really do not want to use primaries. Is it safe to use RCR123a's without the light, I ask because it says nothing about them in the manual. I have noticed that the light will skip modes especially when the tail switch is depressed. At half down my light with 18650 will go from turbo to high. Turning the light back on will bring it back to turbo but within five to ten seconds it downshifts. It is rather annoying. I absolutely love the light on cr123s.


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## kwak (May 17, 2011)

Exact same problem on my TK21 U2.

With my AW 2200mAh cells it steps down almost immediately, when i fit 2 x CR123 cells instead it works fine.


I had some new 18650 Trust Fire 2400mAh cells arrive yesterday, a quick test and it seemed fine with those, so it seems as if it's more a battery problem than the torch.

Weird thing though is that when it steps down, it's as close to high mode as i can tell with my naked eye.
My limited understanding of the cell protection is it's a over/undercharge protection, i can't see that the protection board would be big enough to step down the voltage even if it was a useful function (which i can see no reason for having a cell step down it's output).

So logic would say it's the batteries as other cells work fine, but then i can't see a cell stepping down it's output that quickly for any reason.


Weird.


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## Midnight_Flasher (May 18, 2011)

Thanks for info folks! I need to check this light out! If problems arise, I will first try some unprotected low internal resistance 18650 cells like Sanyo or even certain 1300mah cells used in power tools, then couple of 3.0volts LiFePO4 RCR123's. Unfortunately I have to wait till end of month.. paycheck and stuff, you know..


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## RedForest UK (May 18, 2011)

This problem has been addressed in the TK21/41/70 thread, it seems the light switches down to high mode when the cell voltage under load goes to 3.5-6v or below, to warn about low battery voltage.


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## msm1018 (May 18, 2011)

What I don't understand though is that if you say it's the light warning of a low battery then why is it happening with fresh off the charger batteries?


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## RedForest UK (May 18, 2011)

Well the suggestion would be that the particular cells you are using have a very high voltage sag under load and so on turbo drop below the 3.5/6v mark quite quickly, even if with the load removed they jump back up to a normal resting voltage. The circuit mistakes that for the cell being heavily discharged and cuts down to high mode. 

The circuit could still be at fault however, it may be cutting down at too high a voltage. I'm just pointing out why this is consistently happening, but never with higher voltage cell set-ups such as 2x 3v primaries.


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## Midnight_Flasher (May 19, 2011)

If AW's sag, as has been reported, then should also.. well.. every 18650 cell. I hate this, since I have IMR cells, Sanyos, LG's, Samsungs and also very high internal resistance Chinese cells but not the light. IMRS should be ultimate test for sag hypothesis. One user said that light cuts down when the switch is half depressed. Sounds like the light is very sensitive to current changes.. or plain faulty. If I had light like that, I would use test leads and try how it behaves without tailcap.


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## anylau (May 29, 2011)

I too have this problem... but i use using with a new uncharged aw 2900ma AW... after i charge it... it was ok... but just about 10 or 20 minute playing (all the modes) with the play in 2 days time... it starts to auto dim again ( too quick/early for me )... i would expect it to last longer... i do feel its like an indicator from the light that batt is low... but the thing is... after it auto dim itself to high... u can just click it once, it will be back to turbo and stays there.... until the voltage starts to go down till near 3.6v.. it will start to dim from turbo then high then normal in a few second time... u really should charge it by then....

btu i still feel... the run time is too short for it too auto dim down... i tot 2900ma 18650 should have a longer run time then 2 cr123... maybe i am wrong


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## anylau (May 31, 2011)

anyone have anymore update on this issue? i really wan to know izzit because tk21u2 cannot handle 18650 with protected chip.... ? my freshly charge also will dim down to high... but it's like random.. sometimes it wont dim down.. sometimes it does not... but if fully charge... if it dims down u just click it once to bring it up to turbo.. 80% of time it will stays there... 

i really scratching my head on this problem..


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## joorsh (May 31, 2011)

I had this exact problem.

I can confirm that when my TK21 U2 Special Edition arrived, it displayed exactly the problems the original post describes.

468 lumen mode (turbo) would turn on, but only for a few seconds, and then it would drop back to 180 lumens (high).

*To resolve this problem*, I purchased 2 new high output CR123a batteries. Cheap batteries WILL NOT DO THE JOB. Spend the extra couple of bucks, get high output good quality batteries, and you won't have this problem ever again.


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## anylau (Jun 2, 2011)

I email fenix with this problem... and this is her reply... ( i did told her my battery is fully charge) but i forget to tell her that i did test my fully charge batter was at 4.21v, and when i tested it later it was @ 4.19v... so it's still full... anyway... the reply...

service to me
show details 5:21 PM (4 minutes ago)
Dear Sir

Here is Fenix manufacturer in China.

I'm so sorry if the TK21 cause any trouble to you.

About this model, it has the low volt protection, so if the battery power is not enough, it will jump to the lower mode.

The engineer tell me that if the battery power is not enough, the light will lose the memory function, according to your description, the light output from turbo mode to high mode, that show the power is not enough, so it can't remember the last setting you use.

But when the output stay on turbo mode, it show the power is enough, so it has the memory function, that why" if u switch mode before the turbo mode auto dim down to high... then it will remember ur last setting..."

So maybe you think the 18650 is fully charged, actually, it may be not, you could test the volt, or because the CR123A battery has higher volt, we suggest you try with 2*CR123A battery to see if the light can work well.

Any result, feel free to let me know.

Best regards!




Sincerely Joyce
Fenix Service Team
Website: www.fenixlight.com
Tel: 86-0755-29631183


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## LED_Thrift (Jun 2, 2011)

Has anyone tried it with IMR cells? I'm hoping those work well, because my wallet told me not to feed it primaries.


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## Richub (Jun 7, 2011)

My idea about this problem is that XM-Ls are specified from 3 to 18 volts, so with a single 18650 running at 3.7 volt you'll get below the 3 volt threshold very soon. 
In my opinion running an XM-L on a single 18650 is a bit too optimistic.

Running a TK21 on 2 CR123a batteries gives you 6 volts, and perfect turbo mode.

Even with this issue, the TK21 is nothing short of amazing, it's one of those lights with a very high 'WOW' factor. Small, and bright as hell.


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## anylau (Jun 7, 2011)

would it be ok is i run two Rcr123 3.7v?


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## Richub (Jun 7, 2011)

2 times 3.7 volt is well over 7 volt. So I guess it'll be OK. 

Always use A grade batteries though, poor quality batteries are a definitive no-go in these high-end torches.


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## anylau (Jun 7, 2011)

ya... thats what i'm worrying about... primary cr123 is so hard to get on where i'm staying... i ordered online around USD3.32... but in some cheaper local hardware store i could maybe get it around USD4 (rare case)... photo shops are selling USD10!!! >.<

anyway.. aw protected 3.7 rcr123 consider a grade (black and crome lable)?


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## Richub (Jun 7, 2011)

Don't know... I live in Europe, so all comon american/overseas brands are unknown to me. 

Maybe somebody else knows?


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## kj2 (Jun 7, 2011)

My TK21U2 will come soon. Will check if I have the same problem. I also emailed Fenix today.
But if it's possible to use 2* CR123A (2* 3.7V) then I'll have to find them.


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## muskyhunter (Jun 7, 2011)

I got a TK21 last night and it works great. I used regular 3v 1500mAh and 2900 mAh AW 18650 batteries. It's crazy to believe this light is 1/2 the price of my surefire and 6 times brighter. LOL!!


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## Midnight_Flasher (Jun 7, 2011)

I got mine today. I have not yet time test it for extended time, but no immediate problems with an 18650 cell (4GREER Protected 2400 mAh cell) Also helpful dealer test drive my sample and another one for 15 minutes in full mode before shipment and both were flawless. I have five XM-L's (price tag from 70-150$ - not DX grade toys) than can be driven with an single 18650 and Fenix seems (yeah, completly subjective impression, no data to prove..) to be most hard driven and heat generating of these single cell XM-L's, so maybe its not even meant run for long times in full mode. It wouldnt be the first time, when this kind of light comes out. But then manufacturer should say clearly: use full mode sparingly.


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## anylau (Jun 7, 2011)

yup... i turn on mine full for 5 minutes... i quickly shuts it down to low mode... it's pretty hot....



> but no immediate problems with an 18650 cell



I ENVY YOU!!!!

mine only works nicely on a fresh charge 18650 (aw 2900ma protected) then later awhile it's pretty random... half press dim to high... auto dim down... what also will happen... but later after some extended use... it's getting better... it still auto dim down at times... but lesser...

feels like i'm talking crap... :s


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## Midnight_Flasher (Jun 8, 2011)

anylau said:


> yup... i turn on mine full for 5 minutes... i quickly shuts it down to low mode... it's pretty hot....!!


Do you have pre-order sample from the early production batch? Or do you live in a country that has very hot weather?


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## anylau (Jun 8, 2011)

Oh!! dont talk about the "early production bath" it makes me think back of the led lenser M7 i order~~ serial no. "00030" >.< ... it makes me sad.... 

but how to tell is a early production batch? i check my serial... nothing mention about the MFD also... hmmm :s

yup i do live in a country which is hot... whole year long~~ 
I maybe do exaggerate abit on the hot part.. maybe i just dont want to really abuse my light  but its pretty warm...


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## muskyhunter (Jun 8, 2011)

Ran my tk21 u2 for 30 mins straight in turbo and experienced no problems with aw 2900 18750. Have some 2400 mAh batteries on order and will report after testing.


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## anylau (Jun 8, 2011)

prior to ur last comment on the 15 minute run... i pop out my tk21 u2 (in the Office) use my protrek (pathfinder) and start counting... it serve as a a solar charger for my watch also... 







so 1st 4 minutes it's looking fine... not warm....(but i'm in my air con/server room so it's pretty cold)






I stop at 15 munites Before everyone walking by my office window were looking in at my very bright under-table!! 








Actually it dint get any much hotter then when it's @ the 4 minute time post...

so my tk21 runs problem free for 15minutes(for now) on aw 18650 29000am protected cell!!






Oh btw i dint test in on a full charge battery.. before i started this test run the batt was @ 3.90v (full 4.20v)

after 15minutes... it when down to 3.78v


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## regulation (Jun 8, 2011)

after reading so many thread about TK21, i just have to say that it is really a mystery about the protection funtion on the tk21.


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## anylau (Jun 8, 2011)

Fenix TK 21 U2... U for "Unknown".... hehehe


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## kj2 (Jun 8, 2011)

I emailed Fenix about the problem. This is what they say; 

Thanks for your interest in Fenix TK21.​ ​  The TK21 has the low volt protection function, at present, just this model has this function, it can stop the battery being over-discharged. Because of this function, if the battery power is not enough, the light will jump from higher output level to lower output level, so if his TK21 jump from turbo mode to high mode, it should be the case that the battery power get less, if he want to use turbo mode again, he can recharge the 18650 to 4.2v. ​ ​ And we suggest the consumer use good quality 18650, the power can stand longer, or use CR123A due to higher volt, the rechargeable battery CR123A is OK to use in this model. ​ ​ Best regards!"​ ​ ​


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## anylau (Jun 8, 2011)

more or less the same reply i get from fenix too...


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## kj2 (Jun 8, 2011)

So it is possible to use 2* rechargeable CR123A (2* 3.7V)


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## anylau (Jun 8, 2011)

hey! thanks for remember my question!!! do appreciate it alot!!

i shall move forward to 2 rcr123 (2* 3.7v) set up...


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## kj2 (Jun 8, 2011)

Only question I have now is; is a 16340 battery the same as an CR123A ?


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## anylau (Jun 8, 2011)

true to this.. i also not sure!!! i am also looking for a correct answer for his.. i search and see.. 16340 is abit longer then cr123... so.. i am not sure... fenix bane this battery on many lights...







trustfire ones are 16340...


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## kj2 (Jun 8, 2011)

Well. When I see this pic, I'm sure that 16340 are not the same as CR123A.
Thanks for the pic


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## the_sandman (Jun 19, 2011)

Had my TK21U for four days now- Here,s my issue: in "strobe" mode it cycles from fast to slow and so so on repeatedly without giving me the option to choose a constant strobe rate. No issues with turbo stepping down. Using x2 surefire CR123As. 

Anyone else notice this? 

Fenix's website, reviews nor the box or manual describes strobe working this way. All other Fenix models work the way i expeted this to - Frankly it sucks IMHO.

Feedback anyone? 

Sandman


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## Nokoff (Jun 19, 2011)

the "revolving" strobe is by design. it's not the normal disco light. curious why don't you like it if you like strobes?

I've used it outdoors on some trees, looks cool, and try catching fireflys with this on, good luck!


the_sandman said:


> Had my TK21U for four days now- Here,s my issue: in "strobe" mode it cycles from fast to slow and so so on repeatedly without giving me the option to choose a constant strobe rate. No issues with turbo stepping down. Using x2 surefire CR123As.
> 
> Anyone else notice this?
> 
> ...


 
l


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## kj2 (Jun 19, 2011)

I've my TK21 U2 for a couple of weeks now. Very Very Very happy with it. Although I thought that the beam would throw further. 
But overall, it's a very good light. Slightly green tint on the low mode, but in high-turbo it's all white.
Problems I don't have with it. Ran it for over 45minutes with an Tenergy 18650, and the only thing that happens was that the light got hot  
Ony with the holster Fenix got work at. The piece of the holster that goes over the head of the light is to short. So the velcro will hit a part of the head.
It will result, I think, in a mark on the light during time. I have emailed Fenix about that problem.


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## Nokoff (Jun 19, 2011)

kj2 my thoughts are mostly similar. I've been using mine for a couple of weeks now.

I had read elsewhere the holster is a universal type and wasn't made for this light. I've found the same issues as you. It's of good quality though so it's found other duty for me.

Mine also has the slight green in the corona, on the lowest levels only. High is mostly all white and Turbo is bright white. I buy mostly warms, neutral, and hi cri, though this tint doesn't bother me. That's a compliment . It's no different than any other Fenix I've ever seen.

The throw on Turbo is on par with Fenix's TK40, so I feel it's quite impressive. It feels like I have the TK40 in a more compact design, four well spaced levels, tactical clicky with momentary, a preferable battery type to me as well, and without the slow, fast, and sos blink which I didn't use. 

On the issue of throttling, or stepping, down, I've run mine on Redilast and Solarforce 18650. What I've observed is that it throttles down at 3.75v from Turbo to High, however one click and Turbo is back. The torch then throttles down twice more until 3.6v where it then throttles down to medium. At this point it's time for a charge regardless. I actually appreciate this attempt to conserve my battery for me, and *I can use it to gauge my battery voltage*. The override is at my command, all I have to do is click the button once and Turbo is back. 

There is a lot of quality into this little torch.


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## kj2 (Jun 19, 2011)

Nokoff said:


> kj2 my thoughts are mostly similar. I've been using mine for a couple of weeks now.
> 
> I had read elsewhere the holster is a universal type and wasn't made for this light. I've found the same issues as you. It's of good quality though so it's found other duty for me.
> 
> ...



Well I must say, I'm a little bit spoilt with the throw of my TK41 (A)


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## Richub (Jun 19, 2011)

My TK21 switches back to high after only 5 to 10 minutes runtime on an 18650. 
Switching back to turbo doesn't work as the light switches back to high within a second.

Must be the 18650 that causes it, but it works perfectly in my other 1x 18650 lights: TK11, TK12 and TK15.
So I'm not replacing it. (yet)

Ah well, I'm using CR123as now in my TK21, and the light works perfectly with them.


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## Nokoff (Jun 19, 2011)

whst brand 18650 Richub? ..and is it protected?


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## Richub (Jun 19, 2011)

It's an Ultrafire 2400 mAh protected 18650.






I also have a couple of Xtars, they power my TK35. Also 2400 mAh and protected






I don't know if these are any good, so feel free to advice me on good brands.
Please note that I'm in Europe, and do not have a creditcard, so ordering via internet is a bit troublesome for me.

Thanks in advance.


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## kj2 (Jun 19, 2011)

Richub said:


> It's an Ultrafire 2400 mAh protected 18650.
> 
> 
> 
> ...


I have one XTAR too.  good battery IMO.


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## kj2 (Jun 19, 2011)

I use these batteries for my TK35.


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## the_sandman (Jun 19, 2011)

Nokoff said:


> the "revolving" strobe is by design. it's not the normal disco light. curious why don't you like it if you like strobes?
> 
> I've used it outdoors on some trees, looks cool, and try catching fireflys with this on, good luck!
> 
> ...


 
I guess I'm just used to a single strobe rate on Fenix lights. I wish, as it revolves, I could tap the button and freeze at that rate but oh well. I will learn to like it. My TK11 has just 1 mode (turbo) so what am I complaining abou right. 

Thanks for response. 

PS regarding 18650's: I almost bought one at frys electronics yesterday but soon realized it was designed for use in "builds" ie collection of batteries for use within laptop batteries. I guess many laptop batteries use 18650's within them. I'm not sure if it would have sucked or not but the wires hanging off the ends made me nervous so I passed -I expect I made the right choice.


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## turboBB (Jun 20, 2011)

kj2 said:


> Well. When I see this pic, I'm sure that 16340 are not the same as CR123A.
> Thanks for the pic


 
Well, that's technically comparing size to type but it's generally accepted that 16340 (16mm x 34mm) is used to refer to rechargeable CR123's (or RCR123's) whereas CR123's are your primary (non-rechargeable) cells.

@ anylau, the instruction manual (at least on mine) advises that 2 x LiIon's are a no no.

I was one of the lucky winners of Fenix Outfitters' giveaway and have had my TK21 for a couple of weeks now. I just wrapped up the T20C review so will be getting to a review of this light shortly but for now, given the hot topic on the kick-down from Turbo mode, I'm posting early the runtime I conducted in that mode using various 18650's as well as a test on 2xCR123's (Powerizer's).

The relevant battery stats are provided above each runtime graph along with:
- Voltage of the battery at the start and end of the test
- Current draw as taken right before the test (only AW IMR so far)
- Actual runtime on Turbo until it kicked-down to High (first in HR and then in M so read this as 1.3 Hrs *OR *79 Min)
- For testing on Turbo only (in which case a fan was used), temperature: ambient, the head at start and the max it reached

Axis: X = Time in Min and Y = Relative Output










Cheers,
Tim


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## kj2 (Jun 20, 2011)

Those AW are very good, when I see this graphics. To bad, that they are very expensive compared to Tenergy/XTAR/Ultrafire batteries.
Of course, quality costs money but 15-20 dollar for one battery that's a big no no for me. I'll stick with my Tenergy batteries.


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## ieslei (Jun 29, 2011)

Hi guys, i just received my TK21 U2 last week and ran some tests(runtime) with it already. Just as anylau did i left the flashlight on and pointed to my pathfinder to recharge (great idea anylau). Running on AW 18650 2600mh partially full(4.17v).

On turbo it lasted for exactly -------- 1h33mins
I realized one thing when the battery is lower than 3.8v, always when the flashlight is turned on(when turbo was memorized), after 2 seconds it switches to high, so i have to manually switch it back to turbo(for real this time).... this issue doesnt bother me but it might for some people...I'm happy with my TK21 so far  one bad thing is that some parts of the anodizing peeled off the knurling when i took it right out of the box... And the only thing that kills me is the lack of the belt clip and a strike bezel 
My unit has no donut hole (as previous marriage of SMO reflector and R5 from Fenix), and my tint is a little bit yellowish when its not on turbo(pure white).

I prey Fenix could fix some of these issues in the future.

Hope some of my info helped you guys


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## anylau (Jun 29, 2011)

cpf member with pathfinder will never have "medium batt level" on their watch anymore.... hahaha

i've found out that the issue is due to my aw 18650 2900ma problem... it can't hold turbo mode as long as other lower ma batts.... so i ordered 2 aw 2600am and 1 eagletech 2600am 18650... hopes it will last longer!!! 

mine also yellowish... and i not sure my turbo mode is purewhite... i still see a slight tint of yellow on turbo... but the spill is white.. >.<!


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## Munters (Jul 2, 2011)

I bought my first powerled, a Fenix TK21 U2, together with an UltraFire 18650, 2400 mAh, as this is the only 18650 brand I could buy in the Netherlands (where to buy an AW over here?).
Charged to the max, 4.21 V, the TK21 runs on Turbo mode for 44 minutes, after which it jumps down to High mode. That moment the UltraFire shows 3,74V.

I put the battery in the WF-139 to recharge it. This took 4,5 hours. As the WF-139 is rated to charge with 450 mAh, the TK21 needs 2,7 Ah to run on turbo mode (4,5 * 0,450 / 0,75), does it?

The throw and flood of the TK21 is great, as is the build quality at first sight. Just the beamcolor is yellow/green. I don't bother, I just hate blue led lights.
I compared it to a Fenix E01, with a blue beam, a noname giveaway triple-led, with a neutral/little blue tint, and my Makita worklamp, based on an old Kryton bulb, which does give a very warm light. Compared to the Tk21 the beam is red actually.

From left to right:
- Fenix E01, AAA cell
- Noname, triple AAA
- Fenix TK21, UltraFire 18650/2400
- Makita BML-145, krypton bulb











It is fun to see the small Fenix E01 giving the same amount of light as a noname tripple led, tripple AAA powered led! (no picture)

The TK21 (left), running low mode compared to the E01 (right), shows a yellow/green TK21 beam, compared to a blue E01 beam:





The TK21 (right) has to be run on the second level only, to match the big Makita (left):





The TK21 on turbo now, the Makita light shrinks... (As the pictures are taken with a cheap point-and-shoot, you cannot compare the images, as the timings and settings of each photo differ).





And finally the TK21 beam on white paper. It looks like the throw is yellow, while the flood is white?





From left to right: TK21 (green throw), E01 (blue throw), Noname (no throw)


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## Richub (Jul 2, 2011)

That's right, the hotspot and corona on XM-L lights are more yellow-greenish than the spill is. 

I got 3 XM-L lights, and they all show this color difference between the spill and the hotspot. Of my three XM-L lights, the TK21 is the most green, the TK35 and TK41 are both pure white, the hotspot is a slightly warm white, the spill is slightly purple-blue.


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## anylau (Jul 3, 2011)

Munters said:


> It looks like the throw is yellow, while the flood is white?



yup, mien too is the same.. white on the spill and yellow on the throw... hmmm.... (thanks for sharing your picture)
now only there is a picture like yours.. from those who have a white throw on turbo....


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## Richub (Jul 11, 2011)

Today I got a notice from my store to return my TK21 to them... And I'll get my money refunded.

It turned out Fenix is taking back this first batch of TK21s due to the poor turbo runtimes on most 18650 batteries.

Pity, but a nice service from Fenix. I'll be buying me a TK21 again once this issue is fixed in the next batch.


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## anylau (Jul 11, 2011)

Richub said:


> Today I got a notice from my store to return my TK21 to them... And I'll get my money refunded.
> 
> It turned out Fenix is taking back this first batch of TK21s due to the poor turbo runtimes on most 18650 batteries.
> 
> Pity, but a nice service from Fenix. I'll be buying me a TK21 again once this issue is fixed in the next batch.



wow, so is there anyway to check out and see whether our lights is from the 1st batch...


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## kwak (Jul 11, 2011)

Richub said:


> Today I got a notice from my store to return my TK21 to them... And I'll get my money refunded.
> 
> It turned out Fenix is taking back this first batch of TK21s due to the poor turbo runtimes on most 18650 batteries.
> 
> Pity, but a nice service from Fenix. I'll be buying me a TK21 again once this issue is fixed in the next batch.


 

Mine has this problem.

Do you have a link to an official statement?


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## anylau (Jul 11, 2011)

i just send an email to fenix on this issue... hope they'll reply me soon


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## Richub (Jul 11, 2011)

kwak said:


> Mine has this problem.
> 
> Do you have a link to an official statement?


 Nope, just got a notice from my store when I got there to buy a Fenix bike mount.


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## anylau (Jul 12, 2011)

I've gotten the Reply back from Fenix d...

this is the reply
"service to me
show details 5:51 PM (5 minutes ago)
Hello Keat

Here is Fenix manufacturer in China.

Thank you very much for your interest in Fenix light.

Sorry, as far as I know, here we don't have the recall plan about the TK21, and the 1st batch TK21 is the same as recent ones.

Yes, I know, due to the low volt function, some not very good 18650 may cause the light to jump soon from turbo to high mode, but this low volt protection function can protect the battery well and make longer runtime until the battery power is used up. Meanwhile, the high mode is bright enough for many users to light up, if some users would like to use the turbo mode always, we suggest they use the light with CR123A and good quality 18650, it will be OK.

Thanks again for your understanding and support to Fenix.

Best regards"

So this is what they say... so it might be the shop own quality standards... hmmm i wish i had such a shop at my area... it's really good customer service from ur shop...


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## Richub (Jul 13, 2011)

After going back to the store with my TK21, I decided to keep it anyway...

It turned out that Fenix Netherlands contacted my store to return the TK21s, but at the same time Fenix International still says that there is nothing wrong with these TK21s. (As stated in Anylaus post above.)

So even if these TK21s from Fenix Netherlands are returned, there is still a big chance Fenix International won't replace them, since they say there is nothing wrong with the TK21s.

The storekeeper will contact me though if there is any new information about this issue. Until then I'll just use CR123a batteries in my TK21.


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## kj2 (Jul 13, 2011)

Richub said:


> After going back to the store with my TK21, I decided to keep it anyway...
> 
> It turned out that Fenix Netherlands contacted my store to return the TK21s, but at the same time Fenix International still says that there is nothing wrong with these TK21s. (As stated in Anylaus post above.)
> 
> ...



Well Fenix Netherlands (knivesandtools in Apeldoorn) has noting on there website about this. If have good contact with those people, and I haven't heard about it.


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## bravo-05 (Oct 5, 2011)

i just received the light and am kinda dissapointed. I charged two new ultrafire 3.7v 3000mah batteries only two test them and discover that it dims from turbo to high within 10 minutes. <br><br>now what i am trying to determine is if cr123s will solve this issue (voltage issue) and if i will get the run time of 1h50mins on turbo as stated in the light s specs.<br><br>is it normal that i receive a 10 minute usage using my 18650 batt or is mine defective? are ultrafires usually reliable batts? what cr123 to get?<br><br>thanks.<br><br><br>


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## loquutis79 (Mar 25, 2012)

I have had my TK21 U2 for three months now and I have had no issues with run time at all. I would mention the Energizer Bunny here, but I use AW's
Which brings me to the point. So many people are still using all those *****fire brand of batteries and then wondering why their new expensive flashlight acts funny. I don't know but when I got into this hobby and spent several weekends going over all the info here, I decided to only purchase the best 18650's I could. To many issues with the *****fire stuff. [Tenergy is not much better, IMO]
If cost is such an issue, and yes, I understand that everyones budget is different, than perhaps one should stick with a less costly flashlight.
When you want and pay for a light that puts out 400, 600, 2000 lumens you really cant cheap out on the cells you want to power them with. It is like buying a Ferrari and trying to run it on the "regular' fuel at the "no-name" gas station.
Just my humble opinion.

My Fenix TK35,TK21 U2, PD32 all run very very well on AW18650, 1300mAh batteries. LD12 runs great on the Eneloops also buy the way.
I love my Fenix products.


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## kj2 (Mar 25, 2012)

loquutis79 said:


> I have had my TK21 U2 for three months now and I have had no issues with run time at all. I would mention the Energizer Bunny here, but I use AW's
> Which brings me to the point. So many people are still using all those *****fire brand of batteries and then wondering why their new expensive flashlight acts funny. I don't know but when I got into this hobby and spent several weekends going over all the info here, I decided to only purchase the best 18650's I could. To many issues with the *****fire stuff. [*Tenergy is not much better, IMO*]
> If cost is such an issue, and yes, I understand that everyones budget is different, than perhaps one should stick with a less costly flashlight..



I have no problem at all with my Tenergy batteries. - What kind of problem you ran in to with this brand?


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## C-channel (Apr 5, 2012)

Makes perfect sense. A good light like this Fenix TK21 deserve a good power cell. Assuming that good cells could be charged for 1000 times before the lithium could not hold optimum capacity, it would take approx 3 years to spoil. If really a daily charging is done to the cell. If not, 5 years life for a USD15 cell is worth it.


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