Seems like they confirmed that 2 x 3.7V cells are ok in the regular TK70. REad the TK70 thread in CPF. Someone used 2 x IMRs.
So just use 1 adapter and wire it up internally +/- to make it a dummy, and 2 x 3.7V Li Co from Kaidomain 32600 5Ah. Oatmandu reported 66 minutes in Turbo mode.
So you do not use the extender. Put the dummy cell closest to the head and 2 Li Co at the end to balance things up. This is better than the TK70S, better balanced. And not too long also.
You can charge these 32600 cells with the Ultrafire WF-188, $13 from Manafont. Or if you wanna save, just get magnets.
$183 shipped with registered mail from HKequipment, $2 more for the 4 adapters. This light is a winner with the cheap 32600s from Kaidomain as a set of NiMH and fast charger costs like $86 shipped from batteryjunction.
If they made the driver accept 12.6V, then this light could have done 11-12 days in low mode.
That sounds interesting, however at the cost of a theoretical 50% reduction in run time while using 32600's.
Good D nimh delivers 10Ah verses 5Ah (probably less) from the 32600's.
I think most people would probably like to have at least 1 set of extra batteries for this light so lets take a look at some total investment costs for 2 sets of batteries.
8 x D Tenergy 10,000 mAh NiMH (8 batteries in a bundle) - $58.00
High quality digital Tenergy D NiMH Charger - $34.00
4 x 32600 5,000 mAH LiCo - $17 each x 4 = $68.00
Gets the job done: Ultrafire WF-188 - $13
To get the same total run time, you'd have to invest in a total of 8 x 32600's, bringing the grand total to $149 and still be using a cheap questionable charger with large lithium cells.
We still havent mentioned the risks of stacking 2 cheap chinese high capacity LiCo's in series and the potential of creating a high powered fragmentation bomb. Under no circumstances would I ever stack cheap cells of this size unless they were reputable name brand manufactured balanced lithium cells. Im sure this would also void the Fenix warranty if they could prove that you used lithium. Just because someone got away with pushing the TK70 driver past its intended voltage spec doesnt guarantee it will survive in the long term. Most drivers vent excess voltage as heat and severely reduces the life of the driver. It would be interesting if the driver failed while overheating and created a dead short in this light, igniting those large cheap lithium batteries while several people were within close proximity. That just might make the world news after the ensuing death toll mounted. Lights are also often mistakenly dropped, which can cause failures and dead shorts. In my opinion, large cheap lithium batteries in series is not a good idea, especially when there are other much safer options to power your lights, and as intended by a reputable manufacturer.
Then there's the negligible weight saving to get there. I have D Maglites from 2 to 6 cells. In all actuality, there isnt a whole lot of difference perceived in carrying any of them while comparing 2-3 D cells mags or when comparing 4-6 D cell mags... they are all heavy and bulky.
Im not trying to chastise you 2100, and I know you're just passing on information. At this point, I just think its very bad advise all around to power the TK70 with lithium cells. I'll keep my fingers crossed for the cpf crowd practicing the lithium alternative; that non of them experience venting cells.
It seems that more than a few NiMH D cells have recently dropped in quality so read the current reviews before you buy. Tenergy still seems to deliver as always with their D cell non-lsd version. Ive had mine in storage for 3 months and pulled them out to use in a 4 x D florescent camping lantern. They performed with no appreciable loss in performance that I or my group could detect.
Hi Flashpilot, the details are all in the TK70 thread as well as thaicpf thread. This light/cells have been well tested. I am aware of your good intentions and it is a good call, because i am getting into the RC heli hobby myself and on youtube you do find numerous videos of such stuff. But I have to reiterate that I'm not trying to spread misinformation.
(1) It's not a matter us pushing the light to 8.4V, like us trying to run a Sky Ray 3800 with 3 or 4 cells because the Trustfire 3T6 can run 3-cells. There is a TK70S version which is designated for the Thai market, a "S" or Special For Thailand version which Fenix sells via thaipowerlight. This has a TK50 2D tube/tailcap which you can use with 2 Li Co. Fenix would not sell you a 2D TK50+tailcap replacement, they ask you for your serial number for vertification. Initially, like what you'd have brought up as well as a usual question, are there 2 seperate driver versions for Thailand and for international? It is not running above spec, the light is designed for it. Details all there....in thaicpf and cpf....in fact too much information.
The mistake is that it is not 50% difference in cap....try spotting the mistake? :D
The idea for running w/o the extender with Li Co is to run a 3D length instead of a 4D length.
4pcs AccuEvolution LSD 10000mAh - 63 mins
4pcs Tenergy Premium 10000mAh - interestingly i can't find anybody who has done run time tests on this!
4pcs Imedion 9500mAh - 60 mins
4pcs 9Ah no-brand - 63 mins
2pcs Kaidomain Li Co 5000mAh - 66 mins
2pcs 4 Sevens 26650 Li Co 4000mAh - 54mins
2pcs Ultrafire BRC 32600 3.0V 4000mAh I presume LiFePO4 - 46 mins
2pcs of Panasonic NCR18650 2900mAh, 40 mins (this is a well known cell)
Mitro (you know, the battery guy) has tested this Kaidomain cell somewhat extensively, guns at 5A and returns 4500mAh. Initially I was wondering about its safety and performance. Mitro is trustable, if not we can disregard the whole of Rechargeable batteries forum here already...... so I guess not. Of course I am not saying that everyoneshould be aiming for 99.9% accurate results which need to be certified by at least 3 guys, but hey this is the BLF and land of $40 flashlights (seriously the last time i'd checked that is already considered expensive), i'll make do. :D
I'm sorry if i hadn't put out the accompanying warning label about such cells. I guess I should, but then the same needs to go to those Bestinone.net ones, Ultrafire BRC, TF Flames etc which everyone seems to be using. Forgetful lah... LOL! Of course if one is a newbie and knows nothing about matching cells, better don't. I am trying out the RC heli hobby as well, like i said the guys push the limit much farther but of course the tech level is also much higher than the flashlight folks. The same goes for DIY Audio for HT or 2-ch etc.... The level of technicality there is correspondingly higher, i guess simply because of budget thingy dah... (well I saw several million bucks setups worldwide and you'd think that this is only for Military collectors / mini yatchs / other "BIG" hobbies)
Alright I'll just put the disclaimer here, after all safety is everybody's responsibility, when i was in the Air Force...safety was really top priority. Try to do voltage readings before and after discharge, if possible a hobby charger discharge run and match the mAh capacity. Doesn't matter if you use a $10 cheap DMM, you are trying to compare relative readings, not get accuracy down to the last mV.
In fact for me trying to "balance" cells, I think i can hang around with the best $$ Flukes accuracy with just a cheap meter. Just face the cells +ve with +ve and contact them, measure the 2-ve ends, use the millivolt setting. Quite a few times my Solarforces, XTAR, TF Flames do 0.000, or at most 0.001V.
You are correct, sir: http://www.candlepowerforums.com/vb/showthread.php?309280-AccuEvolution-D-Cells-quality-gone!
Accupower simply use other OEM's for their cell, so it seems a new manufacturer (potentially used by others) is source of the issue.
I saw that too, that's why i purchased Tenergy Centura LSD 8Ah instead of AccuEvolutions. Apparently they measured 8.7Ah, i measured 8.4 and 8.5Ah for my 4 Tenergy LSD 8Ah cells. Good. I suspect it is the charger, the guy should be using a hobby charger or something....but then i am not going to find out at my expense man by buying the AccuEvolutions. I have to pay usd 23 for shipping!
Hi Flashpilot, the details are all in the TK70 thread as well as thaicpf thread. This light/cells have been well tested. I'm not trying to spread misinformation.
No, FlashPilot just made an error in interpreting the Ah metric:
That sounds interesting, however at the cost of a theoretical 50% reduction in run time while using 32600’s.
Good D nimh delivers 10Ah verses 5Ah (probably less) from the 32600's.
Ah is a measure of capacity only when given same voltage in the cell. When comparing different types of cells, it's more useful to use Wh, which is 3.7*5 for the 32600's, and 1.2*10 for the nimh's. 3.7*5 *2 = 37, 1.2*10*4 = 48. There's a difference, but not that much, and the empirical testing shows it's entirely possible the circuit is more efficient @ higher voltage.
Yeah, Watt hr is the metric to use. Anyway I will do my own tests when i get the two KD Li Co of course. Heck even for Panasonic, XTAR, Solarforce I'd have done my own tests for matching under various load conditions (which i have done so many many times..,.you know i stressed the SR3800 under water), ie under 1.3A for my single XM-L and 2.x amps in the regular triple XM-Ls, and of course the you-know-which-lite direct drive 3 cell pipe bombs. :D
Dead short for an unprotected cell is always an issue - that i'd have to admit, "not for newbies". I have a SR3800 shorted driver just 30cm away from me now, if i connect a 2-cell supply to it, the MOSFETs still smoke. :D So yes that is a good call by Flashpilot.
But I am impressed that the Panasonic unprotected cells do not blow even when abused for 30 mins dead short in xxlmm4's video. (you know...that Callies Kustoms guy)
The danger in this setup comes mainly from forceful overdischarge current (ie reverse charge), not from simply a short. A battery's capacity to do this to itself is limited.
To make it clearer in layman terms, you are saying that one cell hits bottom zero capacity and the other is still FULL STEAM AHEAD? ie initial state 1 cell 10% charged say 3.5V and the other cell is 95% charged say 4.15V. And the first cell hits bottom and the other still has 85% to go, shit hits the fan (is this an American slang by the way?) and KABOOM? That could be one of the reason for the DX case of the Trustfire X6, isn't it....
Time to WiKi :
When one cell completely discharges ahead of the rest, the live cells will apply a reverse current to the discharged cell ("cell reversal"). This can happen even to a "weak" cell that is not fully discharged. If the battery drain current is high enough, the weak cell's internal resistance can experience a reverse voltage that is greater than the cell's remaining internal forward voltage. This results in the reversal of the weak cell's polarity while the current is flowing through the cells. This can significantly shorten the life of the affected cell and therefore of the battery. The higher the discharge rate of the battery needs to be, the better matched the cells should be, both in kind of cell and state of charge. In some extreme cases, the reversed cell can begin to emit smoke or catch fire.
In critical applications using Ni-Cad batteries, such as in aircraft, each cell is individually discharged by connecting a load clip across the terminals of each cell, thereby avoiding cell reversal, then charging the cells in series
Aside from doing voltage measurements.....one thing i don't understand is, why people mix and match batteries. Even in $10 low-grade toys that you get in China, you see the ubiquitous warning never to mix batteries. Yep, Alkalines as well. Of course the drain is low, so the most you'd ever get to see is grapejuice coming out from Alkalines.
BTW, I have a piece of s*** charger that does not protect against reverse polarity. Yep.... threw it away, sometimes i do insert batteries in the charger without the lights on (missus sleeping) while i surf the net. Anyway I use Li Po sacks.
Also even for the guys who uses high-dollar brand name Li Co cells, you can't rely on it as 100%. PCBs do fail and slip, i have exactly one which does this and i treat it as unprotected, I shall leave it as undisclosed as I do not wish to spoil other's businesses.
Pls do not smoke when charging flooded lead acid batteries, preferably not SLAs too.
Same for condoms, i'd never rely on it 100%. But I am sure everyone enjoys it RAW. Different stages in life, different priorities. One stage you might be doing 200kph through the city....another stage you'd be teaching others that road racing is bad.
2100, thanks for your thoughts. I just read through all 532 cpf posts (as well as your 37 thread edits... LOL!... wow) and there is some information to ponder. I consider myself a fairly advanced user that is probably quite astute concerning cell quality, cell matching, brand & model, charge & discharge voltages/amperages, wH, mAh, sag, resilience, longevity, discharge curve considerations, user reviews, ISO certifications and numbered production runs... etc, etc. I still wouldnt stack those cheap 32600 LiCO's in series even if they doubled my run time and were given to me for fee. Its simply not worth the risk of a failure to me, or putting others in harms way that would likely be standing close by. I'll leave others to play in the proverbial power keg with the burning match. True that some risk can be minimized with education and experience, but to much remains uncontrollable in that particular serial setup... mainly the unknown of cell construction and probable lack of quality via KD's sourcing at the lowest prices possible. Again, I wish the very best of luck to those that run them in series and hope to never read of a catastrophic failure. Although more than enough 18650's have been proven to operate in serial configurations without incident, many do not. Im still very careful to match new high quality cells for those applications and closely monitor them. If 32600 LiCO's come onto their own and start being manufactured by more reputable companies, i might have another look.
Your summation of battery tests in turbo run time for the TK70 is FANTASTIC! Thank you for that. Its to bad no one tested the very popular tenergy 10,000's because Id really like to know how those fit in the mix. Id surmise that the KD LiCO had the slightly longer run time among the others tested because they are being abused by depleting them far beyond what is normally considered acceptable or safe. From cpf user oatmanutd - (3.40V > drop to high after 66 minute). This means that each cell has been discharged down to 2.20V per cell before the battery warning kicks in and drops the light down to high mode from turbo. Those are resting voltages after the batteries are removed and tested so they are probably @1.9V while in the light and under a high current load. As you had mentioned in the other thread, you can often get away with higher or lower voltages (above 4.20 or below 1). The same can be said of Russian Roulette. IMO, its only a matter of time before you become a statistic of the many that have already suffered if you continue those practices.
Your comments about hobby chargers is interesting, but also many of the cheaper ones arent fit to accurately charge or discharge LiCO's. They are often made up of the cheapest components available and give inaccurate and inconsistent readings as well as have huge variations between channels. Many of the hobby guys get away with them simply because the majority use LIPO4 cells, which are inherently much more tolerant of being abused without incurring a catastrophic failure.
Bro, it is by no mean feat to read all 500+ posts @ CPF, you are on holiday now? LOL!
Sheesh you are correct. I missed that, just like that. Oatmanutd (thaicpf) just discharged it till 3.4V, actually the TK70 is by design rated to kick down from Turbo to High @ 3.6V thereabouts, as clearly measured by bro HKJ (whom i trust to be accurate as well). So (fact 1) that is pretty low....too low for comfort and more likely than not would damage Li Co over several times. I'd report that @ CPF while i am still not banned there.
That is why in a particular product thread, as you can clearly see here it'd be good to throw a mixture of all users from a broad base, with everybody's contribution it'd be quite easy for the intermediate/advanced user to draw his own conclusion whether or not it is useful. "Mod and bypass the protection, at your own risk" describes this type of usage best!
Well i've got the Tenergys but they are LSD Centuras LOL! And seriously, so far i have not run them down, it does get hot. Seriously i don't know how can they gun non-stop for 60 mins. HOT!
So I shall be using the NiMH for general use to be safe, and Li Co for fun use during demos or something where 10-15 mins is the norm. This set as SOP should be pretty ok.
Thanks again for your insight, that really is useful as well as important. For me, i'll definitely be extremely careful in discharging in Turbo. Hit kickdown too often a time and yes i'd agree with you that some day will be a very bad day for some guys. Well actually now i am already doing pretty similar stuff with my DD triple XM-Ls...bleah. But of course using safer/known cells, and i recharge at 3.7V seriously (I want to brightest light). You can see it, but TK70 you won't. I'd list that as a "known issue".