Anyone know the deails on Tesla's new 2170 (21x700mm) cell?

I'm guessing it is still a NCA cell. Does anyone know the technical reasons they went with a new size?



Mike

Arizona_Mike said:

I'm guessing it is still a NCA cell. Does anyone know the technical reasons they went with a new size?

Mike

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There have been a few threads about these batteries including early mention of 20700 instead. I think the reason for the size change vs 18650 is increased capacity per cell along with higher current capability they probably did the math and used formulas with dimensions and power capacity. The one thing that is somewhat true is the larger the individual cell the less of them needed (quantity) and most likely the cost per cell is larger than the cost per volume change.

Knock-offs already are available on certain websites

Lynx_Arc said:

There have been a few threads about these batteries including early mention of 20700 instead. I think the reason for the size change vs 18650 is increased capacity per cell along with higher current capability they probably did the math and used formulas with dimensions and power capacity. The one thing that is somewhat true is the larger the individual cell the less of them needed (quantity) and most likely the cost per cell is larger than the cost per volume change.

Click to expand...

Another advantage of larger cells is that the ratio of the volume of the can to the volume of active material decreases as cell size increases. So a greater proportion of the volume of each cell actually contributes to energy storage as cells get bigger. Also, fewer cells to manage means a less complex (and, therefore cheaper) battery management system.

7 pages of info and links here:

http://www.candlepowerforums.com/vb...ng-18650-s-and-going-with-20700-per-Elon-Musk

There have been speculations in print about the battery capacity and max current, but nothing official from Tesla.

SubLGT said:

7 pages of info and links here:

http://www.candlepowerforums.com/vb...ng-18650-s-and-going-with-20700-per-Elon-Musk

There have been speculations in print about the battery capacity and max current, but nothing official from Tesla.

Click to expand...

Thanks for the link.

Mike

StorminMatt said:

Another advantage of larger cells is that the ratio of the volume of the can to the volume of active material decreases as cell size increases. So a greater proportion of the volume of each cell actually contributes to energy storage as cells get bigger. Also, fewer cells to manage means a less complex (and, therefore cheaper) battery management system.

Click to expand...

I have a feeling aside from perhaps connecting the cells together (wiring,tabbing) the battery management system overall won't change enough to be less complex or cheaper. I think the price/cell is the main reason for the change. If you consider that you can go to a store and buy AA and AAA batteries and also C and D batteries for the same prices even though the size/power of the cells differ considerably one could consider similarly with 21700 vs 18650. It may be the cost of the "guts" of the batteries is considerably less than manufacturing and other costs per cell.
It is possible that as newer more advanced batteries come to market that cell sizes increase dramatically more. It may be we see single cells that end up the size of large coffee containers come to market.

More exciting to me is the USA based Tesla giga factory that will double the world production of lithium batteries. Will a USA factory mean the end of buying dangerous cells from China? I hope.

Might need to modify my chargers and make own housing and protection circuits. But if energy density beats the Panasonic 18650 3400s, I am in.

LiS entry dates keep getting pushed back, as if mere investor bait. 2016,then 2018,now 2020,next 2024. Geeze, if real, sell the dang proto types with caveats, as proof of concept for investment.

http://insideevs.com/tesla-exceeds-double-lithium-ion-battery-life/

5700 to 6 amp hour. Reddit post does suggest better chemistry than 18650. You would have to :1.5 volume, 2x energy. Better guts to casing Ratio.

And no, as a user of headlamps for 10 hour workday inspection, the single 18650 3400ma doesn't cut it. 31 to 35mm 2p18650 3400 buck driven xpl v6 bin, with AR lens, just barely cuts it, as long as cc potentiometer controller .

The lawyers are heard from!

IMRBatteries just announce the availability of the iJow 3000mAh 20700 battery. While I am disappointed that even with the larger size it only has 3000mAh of capacity, the thing that really got my attention is the legal disclaimer that was longer than the actual announcement of the cell. While it doesn't say anything we don't already know, it does draw a line in the sand as far as recognized uses and potential abuses of these cells and Li-Ion cell in general. While in general I am not in favor of the current blanket CYA disclaimers one often sees, I am glad to see a vendor finally stand up and say "Don't do this with our product!". I think the big driver of that here is the 30A current capability, with 40A surge. Shorting one or more of these would be like Spock rigging a phaser to short circuit! :fail: It will be interesting to see how long it is before we see overt disclaimers like this one from some of the other cell vendors.

BTW, I am assuming the seemingly low capacity is due to the formulation necessary to support a 30A draw. Can any of our experts here enlighten us further?