kj2
Flashaholic
Just ordered the TK75 
good price too. Hopefully it will arrive within 2-3 weeks.
good price too. Hopefully it will arrive within 2-3 weeks.
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Fenix TK75(3*U2 LEDs, 2600 lumens)
- Thread starter kj2
- Start date
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ILIKEFLASHLIGHTS
Enlightened
- Joined
- Aug 4, 2011
- Messages
- 652
Just ordered the TK75
I guess you ordered it from Fenix?
I, too, am thinking about this one.
I don't think its possible to buy direct from them.
kj2
Flashaholic
Ordered at local dealer.
So if the batteries are all in parallel and have over voltage protection what would keep me from taking a hobby charger to the battery holder and charging the whole thing at 4 Amps? (1 amp per battery that should get distributed since it's a parallel circuit. )
tthats a good idea!
carl
Flashlight Enthusiast
Certainly, when it comes to the batteries in the extender tube, those batteries can't be in parallel with those in the main body? Or am I misunderstanding things as usual?
martindb
Newly Enlightened
Re: *coming* *new* Fenix E50, TK22 and TK75
Discussion of discount codes isn't permitted outside of the appropriate area of CPFMP - Norm
I ordered a Jetbeam RRT-3 from Hong Kong ebay for £160 (the cheapest I could find in UK was £280) but with this coming out, I'm instantly regretting it.
I think the Jetbeam could be going straight back on ebay and I'll hang on for the TK75.
Discussion of discount codes isn't permitted outside of the appropriate area of CPFMP - Norm
I ordered a Jetbeam RRT-3 from Hong Kong ebay for £160 (the cheapest I could find in UK was £280) but with this coming out, I'm instantly regretting it.
I think the Jetbeam could be going straight back on ebay and I'll hang on for the TK75.
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Oztorchfreak
Flashlight Enthusiast
Hi Carl
I explained the facts of this issue in Post No 47 of this thread.
All of the extra battery packs have to be added in parallel to give the light more runtime without changing the voltage available to the input circuitry in the light.
Series is totally out of the question here as I explained in my lengthy post in this thread.
Even Fenix have photos of their own engineers with about a dozen or so battery packs added to the TK75 and everything still worked good.
Series means more voltage.
Parallel means more stored power and therefore a longer runtime.
Given enough battery packs you would be working with "LETHAL VOLTAGES" in a series configuration at the end terminals or contacts to the light!
Could another member ask Fenix directly regarding the battery pack Series vs Parallel question and put this one to bed once and for all!
Maybe each battery pack has some protection included to stop any interactions or problems between battery packs that are added on to the TK75 with extenders.
Cheers
g.p.
Enlightened
- Joined
- Jan 3, 2009
- Messages
- 387
I would continue to charge 18650's individually since there would be no way to monitor each cell. RC lipos have "balance tabs" that allow the chargers to monitor the individual cells. That way if one is taking a charge faster than the others, the charger can slow, or stop the charge, or even drain an idividual cell before something catastrohic happens.
Davekan
Newly Enlightened
The cells are 1s4p. You can use a hobby charger.
Dave
Dave
Adrenaline_6
Newly Enlightened
The carrier might be setup in a series-parallel configuration {2 banks of 2-18650's for 8.4vdc max} That's why it can also be run on just 2 18650's. This will give you 5200mAh off of 4 Fenix 18650 batteries. This makes sense on the spproximate 1 hour of run time on turbo. 5.2 total amperage drawn divided by 3 = 1.4 amps each led.
So if this is true, don't hook up a hobby charger to the holder. You would be charging two banks of 2 18650's in series.
Hooking up extensions just parallels the same voltage for added runtime.
If it is setup in an all parallel configuration, that would be 10400 mAh total. 10.4 amps divided by 3 = 3.47 amps per led drawn.
So if this is true, don't hook up a hobby charger to the holder. You would be charging two banks of 2 18650's in series.
Hooking up extensions just parallels the same voltage for added runtime.
If it is setup in an all parallel configuration, that would be 10400 mAh total. 10.4 amps divided by 3 = 3.47 amps per led drawn.
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Oztorchfreak
Flashlight Enthusiast
Re: Fenix TK75 additional battery packs and charging them all.
In a parallel configuration of battery packs if you applied the appropriate voltage (be it 4.2V or 8.4V or whatever) to the end point of these packs you cannot be sure which packs will consume what amount of current as each pack may be older or in a different state of charge as compared to the others as you swap the packs around at times.
Forget for the time being how each battery pack has the individual batteries arranged because (1S 4P or whatever) we are only treating each battery pack as one battery for the moment even though there are several 18650 batteries inside each pack because the packs as a whole are what we are talking about here.
The photos I have seen so far show just two points on the end of the battery carriers (the outer circular ring and the inner post to pass the current through to all battery packs and the light as well.
This connection at the ends of each battery holder seems to be just a "pass through" setup.
I do not know yet just where the charge point is on an extender or the TK75 itself yet.
There must be a connector or plug on the end of the TK75 tailcap to allow charging, as I do not know wherelse the whole setup could be charged from.
It should be in the tailacap of the TK75 and the tailcap is always moved to the end of all of the exteneder battery packs.
If anyone knows where the TK75 is charged through please feel free to add your observations or photos to this thread please as I have not yet seen the tailcap in detail to know this information yet.
You also do not want battery packs trying to charge other packs when the charger is turned off as well unless all battery packs have a charge control circuit in every pack to limit the power that can be put back into each pack and let all of the battery packs stabilise with each other.
Each battery pack would have to be provided internally with some sort of charge control circuit so as to let any packs that were in a low state of charge not consume all of the current provided by the charger.
Can someone please add photos of the tailcap of the TK75 to show where the charger is plugged into if there is one and also the ends of a complete battery pack?
UPDATE
I should just check out whether a charger comes with the TK75 and that will answer my question most likely.
ANOTHER UPDATE
I just checked the Fenix site on the TK75 and there is no mention of any charger.
I guess Fenix are playing it safe and uncomplicated and also keeping the TK75 price down to be as affordable as possible to sell as many as possible.
I suppose nobody is really going to put many extenders onto this great looking and probably very much used flashlight into the future as the TK70 has been my main light for night walks and the one I go for when I hear a noise outside.
The TK75 will not replace all of my other lights that are used for different reasons like the EDC ones, household ones that my wife usually grabs to look under the bed etc and the really tight throwers that I have accumulated so far.
Cheers
In a parallel configuration of battery packs if you applied the appropriate voltage (be it 4.2V or 8.4V or whatever) to the end point of these packs you cannot be sure which packs will consume what amount of current as each pack may be older or in a different state of charge as compared to the others as you swap the packs around at times.
Forget for the time being how each battery pack has the individual batteries arranged because (1S 4P or whatever) we are only treating each battery pack as one battery for the moment even though there are several 18650 batteries inside each pack because the packs as a whole are what we are talking about here.
The photos I have seen so far show just two points on the end of the battery carriers (the outer circular ring and the inner post to pass the current through to all battery packs and the light as well.
This connection at the ends of each battery holder seems to be just a "pass through" setup.
I do not know yet just where the charge point is on an extender or the TK75 itself yet.
There must be a connector or plug on the end of the TK75 tailcap to allow charging, as I do not know wherelse the whole setup could be charged from.
It should be in the tailacap of the TK75 and the tailcap is always moved to the end of all of the exteneder battery packs.
If anyone knows where the TK75 is charged through please feel free to add your observations or photos to this thread please as I have not yet seen the tailcap in detail to know this information yet.
You also do not want battery packs trying to charge other packs when the charger is turned off as well unless all battery packs have a charge control circuit in every pack to limit the power that can be put back into each pack and let all of the battery packs stabilise with each other.
Each battery pack would have to be provided internally with some sort of charge control circuit so as to let any packs that were in a low state of charge not consume all of the current provided by the charger.
Can someone please add photos of the tailcap of the TK75 to show where the charger is plugged into if there is one and also the ends of a complete battery pack?
UPDATE
I should just check out whether a charger comes with the TK75 and that will answer my question most likely.
ANOTHER UPDATE
I just checked the Fenix site on the TK75 and there is no mention of any charger.
I guess Fenix are playing it safe and uncomplicated and also keeping the TK75 price down to be as affordable as possible to sell as many as possible.
I suppose nobody is really going to put many extenders onto this great looking and probably very much used flashlight into the future as the TK70 has been my main light for night walks and the one I go for when I hear a noise outside.
The TK75 will not replace all of my other lights that are used for different reasons like the EDC ones, household ones that my wife usually grabs to look under the bed etc and the really tight throwers that I have accumulated so far.
Cheers
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Oztorchfreak
Flashlight Enthusiast
Hi xed888.
Have you bought the TK75 over there?
If so what do think of it so far?
I still have it on pre-order here in Australia.
Cheers
Theres a video on Youtube actually from Fenixligtning. Bwolcott posted it. I dont think there's a charging port shown. And no one has it yet except for some special dealers. I reckon Fenix wants them to release it all at similar times
http://www.youtube.com/watch?v=PM9cTqa7So0
http://www.youtube.com/watch?v=PM9cTqa7So0
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you have to take out the batteries to charge them. if using 20 batteries and charge them directly and one of the batteries is defective, that's a little bit like charging a bomb... I think it's a safety design, though bring some complicated steps.
