Yes, thatâs probably the reason why folks arenât getting much comfortably above 4000 lumens, much less hitting 6000 lumens.
A single cell gunning 6000 lumens at very high amps is going to place a lot of stress and emphasis not only on the 1 x 26650, but also on the springs, the cleanliness of contact points, all the components in the power path.
You cannot use the Keeperpower 26650s, they are like mid current cells only.
The best Keeperpower 26650 vs Liitokala INR26650 @ 20A âonlyâ. I think we need to look at 30A (see subsequent posts).
Yep. To get this power out of a single cell, it is imperative to reduce resistance as much as possible.
The biggest one here is the spring. Why arenât they using dual BeCu springs, or at least, a coated spring? Uncoated copper alloy springs will develop oxides on the layers overtime, boosting contact resistance, and creating hot spots, and boosting the voltage loss even further.
That means even if they are using the highest conductivity BeCu C17500, performance will get worse over time.
Look at djozzâs test on the SST-40. In the best scenarios, cooling and excellent bins, it needs 6A per emitter at 2000 lumens. If you want 6000 lumens OTF as measured in all of our ceiling bounces/lumens tubes/integrating sphere, youâd need much more after factoring all the lens losses, driver losses, heat etc.
Probably need 2400 lumens in dijozzâs test if there is a 17% loss to 2000 lumens OTF, thus 9A per emitter.
I am guessing 27-30A at the tailcap is gonna be needed, a fair bit of which is really heat and not lumens. Donât even dream about efficiency once comfortably past 6 amps per emitter.
At 0,052mOhm of resistance, wouldnât you be trying to pull, at 3,6V average voltage, about 69 000A if there were not other resistances in the circuit, including the cell?
Yeah. Maybe youâd kill the emitters if there was a 6000mAh version of the Samsung 30T and bypasses everywhere.
Seriously just look at other â6000 lumensâ lights measured in our ceiling bounce/tubes/spheres, like our ubiquitous BLF Q8 with 4 x XP-L.
Of course 4pcs of XP-L (at 1500 OTF lumens) is going to be much more efficient than 3pcs of SST-40 (at 2000 OTF lumens each). But even so, we are talking like about 25 amps for the 18650 in 4P config? Or is it closer to 30 amps?
This is a 30A light, if you wanna do 6k OTF lumens, low 20-ish if you want to gun at 5k OTF.
LOLâŠâŠ We need to get the bottleneck out from the tail-end for sure.
Actually thinking about that, we use 2.5mm diameter copper wires here for our 240AC. Thatâs thicker than 12awg. More like 10awg.
Just thinking of a very common and convenient source. And seriously speaking, the 10awg stuff that some electricians source for is suckyâŠâŠthatâs why some of our local setups with air conditioner wirings doing higher currents might cause degrade and subsequently cause fires over time etc.
It might still be âpracticalâ in the real world. A 5-20 seconds burst, then charge 2-5 minutes with a powerbank, then 5-20 seconds burst. Look at the above various batt discharge graphs plots @ high current and how it slides down as to why this is so. Even a VTC6 is doable. Such high-drain cells are able to accept relatively high currents till the very end so itâd be relatively fast top-ups.
For those flashaholic meetups thingysâŠâŠyou know what i mean?
And it would be especially nice for people having winter conditions.
131mm x 41mm head package. Empty weight 213g as per Taobao listing.
Lets face it, there are so many people here in BLF owning MT09R (multiples even) with TA driver and thatâs also around this level in terms of current consumption.
So to be very fair to the light and maker/modder, quite âworkableâ and âpracticalâ, if you can get it from TB direct, one for the collection at that price, perhaps.
Dollar per lumen is actually similar to the MT09R.
There are Samsung 20S for sale in TB, batt pullsâŠâŠseemingly legit from end-user testing, 7 milli ohms. Seller tested 6 milliohms on the YR1030 tester. So the whole thingy is definitely doable from start to finish.
Donât think this has been posted here or in other threads discussing thisâŠâŠ
For the record. I presume that this is legit. Using the Nightwatch 4800mAh 35A store battery.
No mention of ambient temp or what, actually i believe it might be cooled in a certain way as i certainly wonât be able to get my BLF Q8 doing this, no way at all.
OhâŠ.the shop also sells a 26980 tube and 26980 batt. But no info on the 26980 batt specs/ratings.
Maybe need to explore your own sources as well?
Of course thatâd mean youâd charge it with a hobby charger with leads and magnets. I wonder where is the location of the USB-C, so just do it that simplified way and hope it is accurate and safe enough with regards to termination and so does not pop.
BSM mentioned the Samsung 30T, shall add the below for good measureâŠ.The seller does offer 26980 option as well.
I think with a 21700 you probably do not need a spring bypass already, the springs might be all compressed and coils touching each other so thatâs already like ultra low resistance. In all seriousness, be careful, it really might go poof with the 30T. Initial discharge @ 30A load is nearly 3.9V @ 30A, 117W. The light/driver could very well draw more than that since we are removing the springs as the limiting factor and basically li-ion power source as well.
Or even the chinese 26980s if you are taking my 10-12awg bypass post seriously, no matter how lousy you think the chinese cells might seem. I donât wanna to be blamed as a source of a light killer.
Youâre looking at the wrong KeepPower. The 5200mah is an older design. You need to look at the newer KeepPower 6000mah. (The Shockli 5500 is the same battery) This one exceeds the performance of the Liitokala 50A.
Then you also have higher current 26650 cells such as the Golisi 4300mah which can do 30A continuously.
Here is the Golisi against the VTC5A at 30A.
You can also compare the Shockli 4300mah and Ijoy 4200mah as they are close to the Golisi 4300mah.
The biggest âBig 4 Companyâ batteries are the 21700 cells and the 30T is definitely a heavy hitter.
I see, thanks for the info, learnt something new today.
Was replying to Mattheww1950âs earlier comment regarding using the Keeperpower IMR 5200mAh (2015) in this light, didnât know that there is a latest 2017 version.
Those new 2017 Keeperpower IMR 26650 6000 (Shockli IMR 5500 2017 ver) curves look good! Esp the Golisi 4300 Gold, savage even at 30A.=, like a 2X capacity version of the Samsung 20S at 30A.