Power banks with 21700 cells?

[Big_Arcane]

From what I can figure from teardown video’s Anker is using 18650 cells in their larger powerbanks.
Does anyone know they have plans to start using the superior 21700 (21-70) cells.

While only slightly larger those cells offer 40% more capacity.

The slightly smaller 20700 cells offer 31% more
capacity, but I think those cells won’t really make it, because 21700 is the standard
in electric cars (Tesla)

That means more research, which means it is to
be expected capacity will increase more in those cells.

That’s why the bigger 26650 performs much worse
when comparing on volume. And the niche market 32650 does even worse.

[Monk3e]

Probably a little early to jump into them still as the price point is still declining as demand is increasing. found a nice breakdown outlining some differences between them. The overall density makes a difference as to whether 40% increase is even achievable, if the 18650 anker currently uses is a higher density you only get about 25% more juice, but with 40% more weight. Indications look more like the 21700 is a further expanded value, not a groundbreaking tech so its hard to say if the risk of swapping a very stable battery for a newer less proven battery is best.

https://www.dnkpower.com/teslas-mass-production-21700-battery/

[Jesse_Hernandez1]

I can't wait until Anker starts using graphene batteries.

[kumar.sachin]

Unfortunately we are still years away from that. Graphene is extremely difficult to obtain in its purest form. It folds on itself and makes carbon nanotubes which are not as useful. Typically graphene oxide is used in small quantities to boost conductivity of the active material inside of a battery. Inclusion of graphene oxide can really boost the fast recharge capability of the li ion battery. I think this is the best route to take while we figure out how best to use graphene or silicon for better battery tech.

[Jesse_Hernandez1]

nclusion of graphene oxide can really boost the fast recharge capability of the li ion battery.

That's what I meant, I've seen other 10,000mah battery banks that recharge in 40min already on the market.

[Big_Arcane]

Yeah, the expected increase obviously depends greatly on the quality you compare.
I've got the 40% number for good relaible tests. Not just from spec sheets.

Samsung INR18650-35E 3500mAh (tested 3250)
SANYO NCR20700B - 4250mAh (tested 4000)
Samsung INR21700-48G 4800mAh (Gray) (tested 4600)

I think all those cells are quality cells.

BTW those test where done at 10A draw.
On lower draws, as expected for powerbanks, the results are a little higher.

[Big_Arcane]

There is certainly lots of room for improvement in charging speed.
But... that can be also obtained with old fashion cells.

Take a big powerbank. They usually hold 6 cells. Good cells are rated at 3500 mAh.
Let's be very converstative and rate at 3000 mAh.
Max. advised/allowed charging speed is usually the the capacity of the cell.
So a 3000 mAh cell can be safely charged with 3A.
But for the cells lifespan it's advised to charge at 80%, 2.4 A

I'm aware it takes some fancy hardware but the max. total charging speed is 14,4A.
There are some brands slowly moving that way. But they use something like 2x 2.2A.

So, Anker, slap on some ports that can handle some juice.
Don't cap at a lousy 2 amps. because my charger can deliver 6x 3.5A over USB.
(that's excluding it's 2.5 and 1.5A ports, 12 in total)

[kumar.sachin]

10A draw is too high for these cells thus the lower capacity. The advertised mAh are probably done at 1C or less current.