Will the 21-70 Battery (a.k.a. 21700) Replace 18650?

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.

Got these 21700’s last week…



That’s kinda my point… :smiley:

3750mAH for the 21s, 4200mAH for the 26es. Fairly little increase in capacity for a huge increase in volume. Or put the other way, a nice savings in size/weight, for only a small penalty hit as far as capacity.

26650s haven't seen the same level of development. After all, who makes 'em? The PLB 50/55As and similar cells are geared for big electric vehicles (buses and such).

The iJoy 26650 still gives out 4050+mAh at its max continuous rating, 30A.

What if we divide in half the 26650 ratings (≈18650 volume)? Underdeveloped cells. If A123 systems or any other get your sh1t right player would have invested in a good high current 26650 li-ion, things would be different, waay different.

Posted originally on Sat, 09/16/2017 - 19:06; little typo fixup.

Those are far from the best 26650s though…

The shockli ones are like 5600mAh+ and can do plenty of amps.

Mmmm, so they’re at least putting some effort into it.

I’m just wondering why, say, Panasonic wouldn’t apply the same tek to 26650s as they do to 18650s. Then we’d have 26es with assloads of capacity at modest current, or current hawgs at modest capacity. Either way, we’d win.


It basically depends on the number of customers and how many batteries they order. A “few” vapers do not really make a good excuse for updating the technology, the money are in electric cars.

We know the EV market is where the money is, hoping trickeldown or pioneering exploratory tests by the flashlight community with technical backgrounds.

But I never considered how deep the retarding impact that the military and their needs may play in development of new battery technology. For example, i have seen $40 single use lithium sulphur batteries online. The military has deep pockets, life or death needs, and could hog emerging companies’ resources, slowing adoption into needed consumer products. Likely, the public might get the scraps.

Example, keep eye on Sion Power’s Liceron tech.

If i don’t post again, I may be correct. Better to discredit me, as this might discourage North Korea from getting their hands on the next lithium air tech.

We know bike lighting is life or death, thus $1500 headlamps. $6000 search and rescue lights. Our credibility problem may be in our unwillingness to wipe out that next village. And so, the protected 18650b liion may stick around — despite our vaping battery-brothers suicidal path of addiction and subtle second hand genecidal tendencies.

I only know this as english because I recognize all the words.


I can explain why this went over your head:you aren’t affected every day by supply and demand, as I am. I seriously am amazed at how seemingly intelligent, successful people do not grasp the reality of supply and demand. If you don’t, the implication gies over your head. Anytime, anytime demand is raised without furiously pumping up supply, the price goes up. Supply cannot quickly go up for an emerging technology of the next generation safer (under gunfire) and higher energy dense batteries. I see two believable techs. Probably, the rest are hype. I also see incredible military applications, who probably will pay many fold more than the EV market, at least in the short term. This will keep the current tech alive a bit longer in the consumer field. So, imr 21700 will have time for a foothold before something 2x or 3x more energy dense emerges. Supply limited on new tech, military dollar demand is probably larger than one would imagine. Sion’s website already hints at this.

Oh noooo more 21700’s Fodder :person_facepalming:

Not very energy dense, but cheap. More “bang” for your buck. I wonder if knock offs at that mah.