TK40 On Primary Lithiums

Some say yes some say no. Has this been definitively answered?
( Yes I searched, but I never found an explanation.)

MCFLYFYTER said:

Some say yes some say no. Has this been definitively answered?
( Yes I searched, but I never found an explanation.)

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Since I never was able to find a definitive answer, I went to LSD NiMH. I'm glad I did. Great solution for the TK40.

It appears that Fenix never approved officially the use of primary lithium batteries. I have an early specimen and the instruction manual says just 'alkaline or NiMH'.

Kilovolt said:

It appears that Fenix never approved officially the use of primary lithium batteries. I have an early specimen and the instruction manual says just 'alkaline or NiMH'.

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Before I took delivery of the TK40 I had on order, I went to Costco and bought a bunch of Neveready AA Lithiums. When the light arrived, I put the lithiums in it despite the warning against using them. I used the light for a few minutes, playing with all the levels, the throw, etc. Then I bought a bunch of LSD AA's and a charger. The light seemed to perform JUST as well with the NiMH batteries as it did with the Lithiums, so I kept them in the light and used the lithiums for other purposes. I LOVE these low self discharge rechargeable's!! Almost like getting free batteries and the lifespan is really impressive.

BTW this is what you find on 4sevens' site:

Powered by eight 1.5V AA batteries:
Alkaline, Ni-MH compatible. Do not use Energizer Lithium AA cells for this light.

yeah this is also something i'm a little confused about. I heard people previously use primary lithiums with no problems. My understanding is the 'no primary lithiums' statement is fairly new, some people claimed that statement was put in place because people put the batteries in the wrong way and *poof*.

I'd definitely get one if it could run on primary lithiums safely... that way I can load it up and leave it in the car without worries. I wouldn't do that with NiMH and Li-ions, worried about the heat damaging the cells.

I dont understand why you couldnt use AA lithiums. They are not 3 volts each they are 1.5v. So you are not gonna fry anything . It must be because of the "volatility" of the Lithium cells and a user putting them in wrong. I think if you take your time and make sure you are loading them in correctly you should be fine.

They are not 3 volts each they are 1.5v

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They are 1.7v each - so 8x1.7 = 13.6v compared to 8*1.5v -12v for alkies - that extra 13.6v may be enough to fry the led.

from what i understand, lithiums are perfectly fine, but they say that because if you load lithiums incorrectly into the TK40, it might explode. i think they say that for legal purposes; if they say lithiums are fine, then you know someone out there will load lithiums in theirs incorrectly and

i'm not saying it's safe, because i don't know for sure. i think it's probably perfectly fine if you pay attention and load them the right way.

i have 16 energizer rechargeables that i bought specifically for the TK40. they work great.

disclaimer: i am not responsible for you blowing yourself up; live life at your own risk.

note: don't forget to "lock-out" your TK40 when not using it for a while. to do this, turn the light on, then twist the head counter-clockwise until the light goes off, and maybe a quarter turn past off. this will help prevent over-discharge and stop the parasitic drain that exists due to the electronic switch in the TK40.