I have almost convinced myself to buy a TK40 but I do have some final concerns. I'm wondering how the outputs and run times listed on the Fenix website would be affected by using generic alkaline batteries versus NiMh rechargeables. I have no desire to use rechargeables but I might consider other lights if using alkalines will greatly reduce the output or runtime.
Fenix TK40 Question
- Thread starter zlf15
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recDNA
Flashaholic
- Joined
- Jun 2, 2009
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Warning - newbie reply. There are far more knowledgeable people here than I.
The trouble with alkalines seems to be that the high power drain may cause them to leak and ruin the flashlight. I use Energizer Ultra-Lithiums. They are lighter than alkalines, are not rechargeable, and don't leak IME. Apparently there is some risk of them bursting into flame but I don't think Energizer would be in business long if that happened very often.
powernoodle
Flashlight Enthusiast
Or even 8 Eneloops and a charger. Thats how Powernoodle rides. 
The TK40 is an awesome light, btw.
The TK40 is an awesome light, btw.
csshih
Flashlight Enthusiast
do not use alkalines. they will in all probability leak and ruin the light.
The problem with the Tk40 is the power source.. 8 AA batteries.
and with 8 batteries(4s2p?), there is bound to be some reverse charging as the batteries die --because not all batteries have exactly the same capacity.
hence, leakage will occur with alkalines.
The problem with the Tk40 is the power source.. 8 AA batteries.
and with 8 batteries(4s2p?), there is bound to be some reverse charging as the batteries die --because not all batteries have exactly the same capacity.
hence, leakage will occur with alkalines.
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Perhaps you missed the discussion
Fenix TK40 Corrosion with Duracell Batteries
https://www.candlepowerforums.com/threads/23598
Fenix TK40 Corrosion with Duracell Batteries
https://www.candlepowerforums.com/threads/23598
Last edited:
computernut
Enlightened
I've handled a TK40 and it's a very nice light. Using Enerloops or other low-resistance batteries is the only way to fly with a light like the TK40. One of the downsides to regular NiMh is the self discharge if you leave it on the shelf for a month or more. Enerloops don't have this problem. I've left the low-resistance Duracells in things over the winter and they had the same voltage as when I put them on the shelf.
Heres my advise..
If you paid more than $5 for the torch, dont put alkalines in it
I mean, the TK40 is at no more risk of causing alkalines to leak than any other, provided you use it on low and medium and put them in the right way around, but Eneloops will work out cheaper in the long run, and spare you the risk of leaked batteries.
It also means you can charge it up each time your home so your always leaving the house with a fully charged torch.
As others have said, it is a great torch, I love mine to bits
If you paid more than $5 for the torch, dont put alkalines in it
I mean, the TK40 is at no more risk of causing alkalines to leak than any other, provided you use it on low and medium and put them in the right way around, but Eneloops will work out cheaper in the long run, and spare you the risk of leaked batteries.
It also means you can charge it up each time your home so your always leaving the house with a fully charged torch.
As others have said, it is a great torch, I love mine to bits
burntoshine
Enlightened
i concur!
i bought 16 energizer rechargeables just for my TK40; been using them for months and no problems whatsoever. i even left my TK40 in my backpack and it accidentally got turned on in turbo mode!!!! (make sure you 'lock out' yours when storing/carring in something and when not using it for a while). drained the batteries completely and everything is fine.
eneloops are fine fine batteries as well. i use those in all my single AA lights.
Marduke
Flashaholic
Just incase you didn't hear, do NOT use alkalines in ANY light you want to keep. They are dimmer, have less runtime, and will eventually leak and ruin the light you put them in.
They are also about 100 times MORE expensive than using Eneloops.
They are also about 100 times MORE expensive than using Eneloops.
That had to be cookin' hot on something else in the bag.
Guess there was no popcorn near the head :laughing:
burntoshine
Enlightened
no such luck! popcorn would have cheered me up after i realized my new light was blasting away full on with no air circulation in a stuffy pack for a couple hours.
the led was still dimly 'glowing' (like some leds do when the batteries are pretty much dead) when i pulled it out and the light was moderately warm to the touch; i'm sure it was cookin' away until it ran out of juice.
from 7777...
"Due to the overheat sensor in the light i think you are fine. If something like that was really bad for the led it would have gone into thermal runaway and it wouldn't be nearly as bright now. You dodged a bullet and are going to be just fine. In the future you may want to unscrew the back of the light a bit to lock it out."
jahxman
Enlightened
Don't subject your $150 light to alkalines. Output is less, and runtime is not better. And you risk corrosive alkaline goop all over the inside of your really nice light. If you must use primaries, use energizer L91s or EA91s.
Better yet, spring for the NiMH's and charger and save a lot of money in the long run. You're gonna want to use this light a lot; why not go with the cheaper, safer lumens in the nice bright light?
Mike89
Enlightened
I agree about using rechargeables with the TK40. If you're going to invest in this light, you might as well go all the way and and get 16 eneloops (or Imedions which are just as good IMO) and a good charger like the MH C9000. Then you will be all set with one fine light (I have this light and it's the best light I've ever owned) and one fine charger, and no more AA batteries to worrry about.
