Great find!
Thanks! I’ve needed a 21700 to check tune sizing on my scratch build, ordered 2 of those. 4.8Ah is not too bad for the 21700 form factor! Even if it is a ~10A max continuous discharge.
IMR has 21700 IJOY’s (40amp pulse) now…https://www.imrbatteries.com/ijoy-21700-3750mah-flat-top-battery/?mc_cid=91754df226&mc_eid=75ac41df2e
Heh-heh, we got the same email… 
21700 is the future IMHO. Small increase in size for big gains in everything else.
Indeed. Volumetric efficiency (power/size, capacity/size) seems slightly lower than that of 18650. I assume it’s temporary, it should be actually a tad higher. But when considering efficiency of the entire flashlight, they are often better already. But the flashlights haven’t arrived yet…I would love to get an Emisar D4 in 21700. Since the head is larger than battery tube, total size increase would be tiny. Battery would have 40% more juice than GA with about the same power.
Yeah, they should be reaching ~5500-5800ma according to the data I saw last year. Course they only started making these batteries last year, so they are doing ok for such a short development time so far.
With continuous discharge max set around 10A and recommended 4.8A for optimum life, I don’t see these being great for flashlights. The testing I’ve seen to date show an immediate drop to 3.7V when under load, by the time our low voltage protection kicks in they’re only giving 2000mAh capacity (in testing)
I-Joy rates a 40A pulse, which means they too won’t do a continuous discharge rate for say, a triple XP-L. Or even a Luminus SBT-70 for that matter, one, all by itself. So I’m not hedging any bets for these Tesla sized cells to take over our world anytime soon. And besides, carrying extra cells would be all the more difficult due to their sheer size factor.
I got the notifications about the new offerings just like y’all did, but opted out as they won’t run my lights built for the big cells. I need 25-30A continuous, not seeing any of these that will do that. (an Efest 20700 will though….)
Disregard the I-Joys. If you want capacity, 48G will run at nice output (350 mA) for over 13 hours. Often enough for a weekend without carrying spares. According to Mooch, it handles current just like your 20700B does, which is enough for many uses. It may not live forever when overdriven. Oh well…
If you want power, 30T is scheduled for the next year and it’s a good deal more powerful than VTC5A. Or Efest 20700 for this matter.
The Efest 20700 has given me absolute best numbers in my scratch built triple XHP-50.2, tested against 20700A, 20700B, LiitoKala blue and black 26650’s and even TrustFire 32650’s, as well as 30Q, Sony VT-C6, LG-HE4, HE2, Efest 3000 in 18650’s.
To better the Efest 20700 will, for me, be a new benchmark indeed. Will be looking for that…
The 48g is not a high discharge cell, think of it as a larger GA instead. Not the highest output but long battery life. Perfect for most real world use lights.
I bought 2 of the 48G, they both test slightly over the 4.8Ah at 4.2A rate. Yeah, it won’t push the highest current, but it will be able to run a light at a very good sustainable brightness for a long time.
This is what I have found to be the most important to me as time moves on. For most lights more then ~5A a cell just means it overheats faster. My EDC triple generally doesn’t get more then 2.5A. I only kick it up to turbo and 10A for short bursts (GA cell).
Yep I can dig it T/A just built a Trustfire T90-2 3S-32650’s to a 70.2 at 10amps in Turbo with the massive heat sink and the 6000mAh batteries it should run for a very long time! Just got to do a little more work on the HX-1175b1 driver, so far so good!
I agree, super high turbo is a fun toy but I generally use 1000 lumens or less 98% of the time, so longer runtime is exciting for me. Most of my stuff is fairly close up though, so of course different use cases have different requirements.
The main issue with 21700 now that the cells are becoming available, is actually finding a host or light made for them. Hopefully the manufacturers start making some compatible stuff soon.
In the meantime I’m going to try to build my own. Should have a bit more time to play with that coming up. Planning on making a quad tube light, sort of like a scaled up E2-L.
Fasttech has them also. The cell itself is a tiny bit more expensive, but the shipping cost to NL is not so draconic.
Recently reamed a Warsun tube to 21.4mm, so I ordered a 48G just for fun. Let’s wait and see.
The iJoys KawiBoy1428 mentioned turned out quite good I'd say: iJoy 40A 3750mAh 21700...hugely overrated but better than NCR20700B
The NCR20700B yielded ≈3850mAh at 10A, so those china made iJoys look really nice with their 3650mAh at the same current while delivering a maximum of 24A continuous (Mooch's capacity measurements are a little bit lower than HKJ's ones due to slight probe voltage drop; you can see this comparing their Samsung 30T discharge graphs, for example). 
Who makes 'em? YDL (Aspire 18350s)?
Cheers ^:)
So how close are these to decent 26650s?
Eg, I got some LK 26650s for my 26650 lights, and even though they’re (LKs) great, they (26650s in general) don’t have the same capacity/current/etc. per unit volume as 18650s.
I’m just thinking… if they push 20s and 21s with the same caps as 18s, the 20s/21s could easily surpass even 26es.
Ironic… use a physically smaller cell for more capacity and current.
