Fenix TK40 on 4AA....

Anyone here did any extensive test of the TK40 just on 4AA?

One review notes that the output is the same initially.

I'm wondering:

1. On Turbo, what's the battery life? Is it half or less than half?

2. Is the MC-E wired parallel or in series?

Asking because would love to see the TK40 shortened for 4AA exclusively. Can call it 'stubby'. A sub 1 hour Turbo run on NiMh won't bother me at all and the length reduction will be noticeable.

Fenix could just make an aftermarket body and cell holder for it.

(Am I alone in this or does it resonate with some of you?)

Moses

Fenix recommends not to use the turbo level with just 4 cells. The reason is that the current is too high for just one series of AA batteries. The normal feeding is at 6V i.e. two sets of 4 AA's in parallel.

Even 4Sevens feels that 8AA is a bad idea.

Well, at least we have a light that uses MC-E AND AAs - again (think of the TK20), Fenix is the first manufacturer to introduce new ideas into the market.

I also don't see why 4 good NiMHs wouldn't survive the draw. Look at some discharge curves - 5 Amps, 10 Amps...of course, the usage with 8 pieces should be healthier for the batteries .

The runtime, I estimate, should be slightly less than a half, considering that 8AAs provide better efficiency.

defloyd77 said:

Even 4Sevens feels that 8AA is a bad idea.

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Will you guys knock it off already.

moses said:

Anyone here did any extensive test of the TK40 just on 4AA?

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Sure, check my TK40 review It is in czech language, but I hope the graphs are understandable...

moses said:

1. On Turbo, what's the battery life? Is it half or less than half?

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Slightly less than half. You can get around 1 hour runtime with 4 good quality AA batteries. I wouldn't recommend running 4xAA alkaline at turbo mode.

moses said:

2. Is the MC-E wired parallel or in series?

Moses

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I have no idea :shrug:

defloyd77 said:

Even 4Sevens feels that 8AA is a bad idea.

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Didn't have a single problem with 4xAA or 8xAA configuration yet. Just be careful when inserting the batteries and alway make sure that you use batteries with the same state of charge.

My very unscientific test with 4 AA was as expected.
Works fine and yes you can screw up the light if you're an idiot. I can also drive my vehicle into a tree, but I don't.
People who wish to see this backup feature as a flaw are digging. People who wish to redesign the light may do so at any time. There are many trees. Knock yourself out

ubetit said:

Will you guys knock it off already.

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Knock it off? It's called ANSWERING A QUESTION.

defloyd77 said:

Knock it off? It's called ANSWERING A QUESTION.

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1. On Turbo, what's the battery life? Is it half or less than half?

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Even 4Sevens feels that 8AA is a bad idea. <--Assuming the statement matches with this question.

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Are you saying that it is a bad idea to use turbo mode even when there is 8AA? Can I get a link to where 4Sevens says that 8AA is a bad idea even for turbo mode? I just bought this flashlight, but if I'm not supposed to use turbo, I might just have to return this then.

Shimon said:

Are you saying that it is a bad idea to use turbo mode even when there is 8AA? Can I get a link to where 4Sevens says that 8AA is a bad idea even for turbo mode? I just bought this flashlight, but if I'm not supposed to use turbo, I might just have to return this then.

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good read for you https://www.candlepowerforums.com/threads/242046

4 sevens did say that but there may be some info here to put you at ease

how bad could it be, the sony/dell battery explosions in laptops were kinda small and those were 18650 so smaller AA would be half as bad of a fire :tired:


i think 4aa would be fine and safe for any level but turbo " you can use turbo but i wouldnt do it for to long" but that just my opinion

Dark Laser said:

I also don't see why 4 good NiMHs wouldn't survive the draw. Look at some discharge curves - 5 Amps, 10 Amps...of course, the usage with 8 pieces should be healthier for the batteries ..

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+1,

I have run mine on 4 eneloops, and also on 4 high-discharge ELite 1700s - brightness on turbo seems about the same , and the batteries were none the worse for wear after, according to my charger.

Dark Laser said:

Well, at least we have a light that uses MC-E AND AAs - again (think of the TK20), Fenix is the first manufacturer to introduce new ideas into the market.

I also don't see why 4 good NiMHs wouldn't survive the draw. Look at some discharge curves - 5 Amps, 10 Amps...of course, the usage with 8 pieces should be healthier for the batteries .

The runtime, I estimate, should be slightly less than a half, considering that 8AAs provide better efficiency.

Click to expand...

+2

Only buy 8 LSD (eneloops...) and a good charger-analyzer like MH-C9000

It depends on the batteries used. The TK40 and other single P7/MCE lights need ~3A.


The Energizer can not produce 3A. So you need 8 Energizers to provide enough power for Turbo.


the Eneloop can provide up to 8A without problems. 3A is a piece of cake. Running the TK40 on 4 Eneloops is fine. You will get less than 40 minutes of runtime though.

To check if your batteries can handle 3A check here:
NiMh Battery Shoot Out.
https://www.candlepowerforums.com/threads/79302

Silverfox did not bother to check alkaline AA batteries beyond 1A because they are so anemic. So use 8 alkalines.
Alkaline Battery Shoot Out.
https://www.candlepowerforums.com/threads/64660

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While the circuit board will convert 4.8-6V lower current to 3.6V 2.8A, there are loses in the circuit board, switch, wiring etc. so it is better to use 3A as a rule of thumb number.

Never tried mine with just four batteries, nor will I. Things would have to be really bad for me to be down to my last few cells, so bad I would be looking for more ammo and not worried about my TK40.

defloyd77 said:

Knock it off? It's called ANSWERING A QUESTION.

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Actually, you're regurgitating one man's opinion... if he even said that.

ubetit said:

Actually, you're regurgitating one man's opinion... if he even said that.

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Oh wait here it comes http://www.cpfmarketplace.com/mp/showpost.php?p=2316468&postcount=23

Man that's the last time I'm going to regurgitate a reputable dealer's stated experiences.

defloyd77 said:

Oh wait here it comes http://www.cpfmarketplace.com/mp/showpost.php?p=2316468&postcount=23

Man that's the last time I'm going to regurgitate a reputable dealer's stated experiences.

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I can manage to put my batteries in correctly.

I'd also like to hear from more dealers or Fenix itself. Myself and plenty of others haven't had a problem with their lights and I use mine often, although with Eneloops.

Seems like 4-7s statement is based on a bunch of people putting batteries in wrong. I am amazed they would take back lights damaged by blatant user error, they are a cut above over there at 4-7s store!!

But seems to me 6-8 NIMH AA batteries are just as safe as 2-6 LiIon 18650s and there are multiple lights out there using that battery config.

I dont think NIMH AA vent and explode do they?

I know 18650s can vent and explode and I personally dont think I would feel confident in a light using 2-6 18650 LiIons yet noone seems to think twice or say anything about the inherent risks with that setup?

litetube said:

Seems like 4-7s statement is based on a bunch of people putting batteries in wrong. I am amazed they would take back lights damaged by blatant user error, they are a cut above over there at 4-7s store!!

But seems to me 6-8 NIMH AA batteries are just as safe as 2-6 LiIon 18650s and there are multiple lights out there using that battery config.

I dont think NIMH AA vent and explode do they?

I know 18650s can vent and explode and I personally dont think I would feel confident in a light using 2-6 18650 LiIons yet noone seems to think twice or say anything about the inherent risks with that setup?

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Regarding the NiMH AA cells, it's possible that one or more cells could be at a concernable lower voltage than the rest, maybe it will just damage the cell by reversing the voltage or it could rupture. I personally avoid lithiums and LiIons, but you're right about the fact that nobody thinks twice about them.

If one were to use NiMH cells right away, would one be best with high capacity or low self discharge, due to lower internal resistance?