Really good review of the TK40

Found this on my travels
http://www.youtube.com/watch?v=z7m1k2tCrYs

I don't know if this person is on the forums already, but I just thought it was a really good review for somebody like me who isn't a flashaholic (...yet?).

What I liked about it was that he's gone to the trouble of not just doing beamshots in a real-world scenario, but also taken the time to show you the size and weight fully loaded, plus how the batteries fit in etc, so you get a really good idea of what it's like.

I'm not saying anyone elses review is bad by the way, just I thought this one was particularly good.

Very nice review.


Still want to get my hands on one!

Me too, but I have to save up a bit each week first! :sigh:

I heard it can only run for about 10 minutes on turbo due to insufficient heat dissipation, which limits its appeal for some.

That is a good review.

LeifUK said:

I heard it can only run for about 10 minutes on turbo due to insufficient heat dissipation, which limits its appeal for some.

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http://www.4sevens.com/product_info.php?cPath=22&products_id=696 Seems like two hours...

LeifUK said:

I heard it can only run for about 10 minutes on turbo due to insufficient heat dissipation, which limits its appeal for some.

That is a good review.

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It's no different than a car manufacturer telling you not to drive faster than 55 mph during the first 500 miles after buying a new car, or when [insert tire shop name here] tells you that following a tire rotation you have to come back after 50 miles to re-torq the lug nuts. +99% of the time you are safe to ignore the advice, but it is there for them to cover their behinds if you aren't cautious with your disregard for the warning.

Great video review.
I wonder which is brighter....the tk40 or the m1x?

The main thing with the TK40 is it runs on AAs, which is great seeing as how pretty much every newsagent, supermarket etc. sells them, and eneloops can be got for about $10 for 4.

Find me another flashlight that's about as bright, has so many good usable power settings, and runs on AA and I'm interested. I'll be turned if you can find one that has a beam to spot adjustable head.

I also have this crazy idea that I could build a hotshoe mount for my DSLR or camcorder, and have the thing mounted to my camera for some night-time photography. The TK40 probably has a more suitable type of light than a flash at night, which tends to stress anything you're pointing at far more than a bright flashlight would.

LeifUK said:

I heard it can only run for about 10 minutes on turbo due to insufficient heat dissipation, which limits its appeal for some.

That is a good review.

Click to expand...

the TK40 is limited to 10 minutes on Turbo because of heat dissipation?? On the basis of my two (2) TK40s, I can assure you that impression is not correct.

I held one TK40 in my hand somewhere between 30-40 minutes on turbo for linemen fixing a failed power line in the area. Although the TK40 head was warm, it was certainly not hot. The lineman really liked the amount of light it put out, much better than the 2 spotlights on the truck. The other TK40 I ran probably 20 minutes on high, also with no overheating or reduction of output.

Frankly so far I have not observed any situation with the TK40 on turbo in normal use that would either reduce the output because of heating, or cause me to back off on the output because of heating. I normally use the TK40 outside on turbo - I purchased it for the 600+ lumens.

Cosmo7809 said:

http://www.4sevens.com/product_info.php?cPath=22&products_id=696 Seems like two hours...

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Manufacturers specs may say N hours, when what they mean is a total of N hours, in bursts of X minutes. In some lights the circuit automatically switches to a lower mode after a fixed time on max.

The manufacturers specs are not always to be taken at face value. The L2D Q5 is quoted as running for 1.8 hours on turbo, and the manual says not to run for more than 10 minutes on turbo. Mine seems to run on turbo for the full 1.8 hours although it does get fairly warm.

moldyoldy said:

the TK40 is limited to 10 minutes on Turbo because of heat dissipation?? On the basis of my two (2) TK40s, I can assure you that impression is not correct.

I held one TK40 in my hand somewhere between 30-40 minutes on turbo for linemen fixing a failed power line in the area. Although the TK40 head was warm, it was certainly not hot. The lineman really liked the amount of light it put out, much better than the 2 spotlights on the truck. The other TK40 I ran probably 20 minutes on high, also with no overheating or reduction of output.

Frankly so far I have not observed any situation with the TK40 on turbo in normal use that would either reduce the output because of heating, or cause me to back off on the output because of heating. I normally use the TK40 outside on turbo - I purchased it for the 600+ lumens.

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That is good to know and it is what I want to hear.

What was the outside temperature? My L2D does not even feel warm when the air is ~0 Celcius, as I found out when I went for a 1 hour run one evening, but indoors where the air is at 20 Celcius it does get pretty warm.

Incidentally the 10 minutes on turbo limit is something I read in a thread on this forum from a user and I hope it is wrong.

Magic Matt said:

Find me another flashlight that's about as bright, has so many good usable power settings, and runs on AA and I'm interested. I'll be turned if you can find one that has a beam to spot adjustable head.

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https://gearupeurope.com/(S(3rnkktf...ights/iTP-A6-Polestar-Christmas-Gift-Set.aspx

Reviewers seem to be suspicious of the battery carrier, and I'm not sure how warm it gets in turbo. Looks appealing.

I love the idea of going for a run cross country and scaring the beejazuz out of anyone carrying a baby torch. It's also nice to see potential threats rather than simply seeing some distant glowing eyes, and hearing a growling as fido sizes me up.

LeifUK said:

The manufacturers specs are not always to be taken at face value. The L2D Q5 is quoted as running for 1.8 hours on turbo, and the manual says not to run for more than 10 minutes on turbo. Mine seems to run on turbo for the full 1.8 hours although it does get fairly warm.



That is good to know and it is what I want to hear.

What was the outside temperature? My L2D does not even feel warm when the air is ~0 Celcius, as I found out when I went for a 1 hour run one evening, but indoors where the air is at 20 Celcius it does get pretty warm.

Incidentally the 10 minutes on turbo limit is something I read in a thread on this forum from a user and I hope it is wrong.

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Air temp for the ~40 minute run for the lineman? about 10 degrees C. Most of the time when I use the TK40s, the air temp is below 20 deg C and I am holding the TK40 in my hand.

As for the battery carriers, I wonder about the longevity but have no data points.

Beam pattern: I have noticed that TK40 #1 that shipped months earlier than TK40 #2 has a slight dim spot in the center of the beam as observed at about 25 meters on a white garage wall. No dim spot is visible in normal usage. I do like the TK40 spill/spot shape - a good compromise. I do not like looking down a light tunnel with little or no spill. Spill is very useful to discover what is next to the spot - such as 4 legged somethings walking in the woods when your only clue is cracking branches or twigs.

LeifUK said:

https://gearupeurope.com/(S(3rnkktf...ights/iTP-A6-Polestar-Christmas-Gift-Set.aspx

Reviewers seem to be suspicious of the battery carrier, and I'm not sure how warm it gets in turbo. Looks appealing.

I love the idea of going for a run cross country and scaring the beejazuz out of anyone carrying a baby torch. It's also nice to see potential threats rather than simply seeing some distant glowing eyes, and hearing a growling as fido sizes me up.

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I suppose they have concerns but someone here did a torture with no failure of the carrier. I'm not sure any other LED hand cannon here has been put through the same amount of abuse yet as a test.

https://www.candlepowerforums.com/threads/233856

Cartman said:

I suppose they have concerns but someone here did a torture with no failure of the carrier. I'm not sure any other LED hand cannon here has been put through the same amount of abuse yet as a test.

https://www.candlepowerforums.com/threads/233856

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The link I gave was to another make of torch, the ITP A6 Polestar. The comment about the battery carrier referred to that torch, not the Fenix TK40. The Polestar is half the price of the TK40, and sometimes there is a reason why something is cheaper.

LeifUK said:

I heard it can only run for about 10 minutes on turbo due to insufficient heat dissipation, which limits its appeal for some.

That is a good review.

Click to expand...

I have a TK40 and left it on for 1hr and 10 minutes yesterday standing on it's tail while I worked on the computer. It was fairly warm when I shut it down but still running at full brightness (to my eyes anyway). I pulled up the manufacturers specs right after that to see how long it was suppose to last on high. That is when I noticed the warning not to run it on high for more than 15 minutes at a time and a runtime listed of one hour. Seems rather conservative at least with my TK40.

I was using the Rayovac 4.0 LSD batteries. They were still reading 1.295 volts on the multimeter out of the light. I was fairly impressed.

I then ran it for another 25min with only 4 Duracell precharged batteries. Once again I could not notice any dimming during this 25 minutes and the light appeared just as bright as when using 8 batteries.

Not a scientific test by any means but I'm impressed with the batteries and the light.

I thought the warning was only for the Turbo mode. I've found several different theories as to why - the most plausible to my mind is that it would be really stressing alkaline batteries and they could overheat over a prolonged period, whereas NiMH would cope, and also that the heat sink design does not convect heat away from the LED very quickly, so it could be running the LED too hot whilst the torch body itself only gets warm, being unable to dissipate the heat quickly enough.

The A6 looks like a nice torch for the money, though the beamshots I found after searching show it to have far less throw than the TK40. It is a lot cheaper however!

Magic Matt said:

I thought the warning was only for the Turbo mode. I've found several different theories as to why - the most plausible to my mind is that it would be really stressing alkaline batteries and they could overheat over a prolonged period, whereas NiMH would cope, and also that the heat sink design does not convect heat away from the LED very quickly, so it could be running the LED too hot whilst the torch body itself only gets warm, being unable to dissipate the heat quickly enough.

The A6 looks like a nice torch for the money, though the beamshots I found after searching show it to have far less throw than the TK40. It is a lot cheaper however!

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The A6 does look nice, but I reckon the battery carrier is the weak spot. I would not risk it for running as the reviews are too inconclusive.

You might be right about the heat. Another guess is that it overheats when used in hot climates e.g. the tropics. My L2D on turbo did not even get warm on a frosty night.

I'd like to pop a temporature probe near the LED on the heat sink and see how hot it's getting closer to the junction. Not having a TK40 (yet?) I can't do that though.

OT: Been looking at your website - fantastic pics! I really must get back into my macro photography.

moldyoldy said:

I normally use the TK40 outside on turbo - I purchased it for the 600+ lumens.

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Same here. Sometimes high is plenty but what the heck, let it burn bright.