Samsung 33J - a 21700 Li-ion battery designed for Tesla

Original article: https://www.thunderheartreviews.com/2019/02/Samsung-33j-21700-Li-ion-battery-for-Tesla.html

Samsung INR21700-33J is neither a high drain nor a high capacity cell but it's a very interesting battery thanks to its impressive cycle life. It's designed for Tesla and is ideal for using in big battery packs.


The battery was bought from my reliable supplier (Queen Battery) and tested with ZKETECH EBC-A20 and a self-made battery holder. It's a PC-connected battery tester supporting 4-wire measuring and discharging at up to 20A.


I've used version 3.0 of my battery holder based on 0.5mm thick pure copper terminals



I've followed all the prescriptions of the IEC61960-2003 standard concerning battery's capacity measurement. Before each discharging cycle each battery was charged at standard charge current mentioned in its datasheet to charge end voltage. Before each discharging or charging i've held a 1-1.5hrs pause. The environment temperature was 23.0-24.5°C. To be sure in results i've done each test minimum twice (usually 3-4 times).


Samsung INR21700-33J

The cell is marked as INR21700-33J SAMSUNG SDI 2H64. The H64 means it was produced on June 04 2017.


The main specs from Samsung 33J datasheet:
Typical capacity: 3270mAh
Typical energy: 12.0Wh
Minimum energy: 11.4Wh
Standard charge current: 1.6A (0.5C)
Maximum charge current: 3.2A (1C)
Charge cut-off current: 64mA (0.02C)
Charge end voltage: 4.20V
Recommended charge end voltage: 4.10V / 160mA cut-off
Max. continuous discharge current: 6.4A (2C)
Discharge cut-off voltage: 3.0V
AC impedance at 1KHz: 29±5mΩ
Weight: 62±1.5g

The manufacturer recommends charging this battery only up to 4.1V. In that case the cycle life of the battery gonna be about 2000 cycles while keeping more than 75% of it's capacity. Don't forget that this cell is designed for Tesla.



Measured DC IR at 3.2A in fully charged condition was 34±1.5mΩ

Measured weight of the tested cell was 62.81g


Capacity test results:

At 0.2C (0.64A) 33J's capacity is noticeably more than the declared 3270mAh and the energy more than 12.0Wh. At 5A the capacity is 3200mAh and the energy - 11.09Wh. I would not recomment to discharge this cell at more than 5A because this is a low drain cell. Also pay attention to the discharge cut-off voltage - it's 3.0V vs 2.5 we usually see in Li-ion cells' datasheets.

Samsung 33J doesn't impress with its capacity or max discharge rate but it's enormous (for Li-ion) cycle life makes it an interesting cell for a wide range of applications where long life is critical.

Here is the video version of this review:


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Something doesnt seem to sound right with this...
Why would Tesla want this cell over their existing 4.8 Ah cell , or even the 3.1-3.3Ah , 18650's they already have access to. ?
This is bigger and heavier than the 18650, with no advantage in output, and Tesla have never had an issue with cycle life..( 8 year pack warranty ?)
This cell just doesnt seem to make sense for Tesla.

I call your bluff. Where does it say it was "designed" by Tesla? I agree and call bs on this. My only guess is maybe it's made for their power wall applications. Obviously not their ev's... At this point Tesla is maximizing charge current, discharge current and capacity...basically the three holy grails of all batteries. Their acquision of maxwell should hopefully drastically increase capacity in a few years after they integrate their technology. I can easily see at least 6000mah out of a 21700 cell by 2021. Maybe 7000mah

Hillhater said:

Why would Tesla want this cell over their existing 4.8 Ah cell , or even the 3.1-3.3Ah , 18650's they already have access to. ?

Click to expand...

Only Tesla's guys know the answer I think. But if they buy this they need this.

Philaphlous said:

I call your bluff. Where does it say it was "designed" by Tesla?

Click to expand...

Did i say "it was designed BY Tesla"?????????????????

Guys, as I've said somewhere else, this is actually a cell that's used in the Tesla PowerWalls 2.

They want to meet max production capacity for the Tesla cars, so they turn to other battery manufacturers for the PowerWalls 2s.

Ahh ! , so for the powerwall they are prioritising cycle life at the expence of energy density.
Now that can make sense for a static pack.
But, it also highlights the compromises that are forced by the limits of current Li technology ! :| :?

Hillhater said:

But, it also highlights the compromises that are forced by the limits of current Li technology ! :| :?

Click to expand...

I just don't understand why Tesla uses these cells and not Boston-Power Swing 5300 or A123 Systems' ANR26650M1Bs (or other LiFePO4 cells). Swing 5300 does 3000 cycles at 80% DOD and 2000 cycles at 90% DOD while being a regular 3.7V Li-ion cell.

ANR26650M1B and another high quality LFP cells are still much more expensive than NMC cells. Swing 5300 is cell with sufficient parameters for ESS but my guess is that it is not cheaper than Samsung in high volumes and more important Boston Power company already did not exist, and also they probably cannot produce enough cells for Tesla demand.

Another reason is that Tesla-Panasonic NCA cells are not good for continuous cycling which is expected in ESS use. Particularly new NCR21700A cell with 5 Ah is suffering a lot in this mode of operation. Samsung and LG 5 Ah NMC competitors does not have a problem to run in this mode of operation. Modern NMC cell with 3300 mAh capacity in 21700 format is already practically immortal when cycled at 80% DoD.

I believe the story of these cells goes something like this:
When Tesla supplied the first of their large Power Pack grid utility storage systems to Southern California Edison (SCE) in 2016 it was built using Tesla-Panasonic cells. The nominal rated capacity of the system was 80MWh.
In March 2017 Tesla offered to supply an even larger Power Pack system for the Hornsdale Power Reserve (HPR) in South Australia. Elon Musk offered a deal in which, if the system wasn't supplied and commissioned within 100 days it would be free.
Following a tender process which Neoen and Tesla won, the contract proceeded on this basis.
However Panasonic advised that they could not supply the 10+ million cells required to build the system (capacity 129MWh) in the required timeframe, and Tesla switched to Samsung SDI for the cells.
The system was commissioned on 1 December 2017 and is the world's largest lithium-ion system until the Tesla Megapack at PG&E Moss Landing is commissioned.

https://hornsdalepowerreserve.com.au/

https://cleantechnica.com/2017/09/30/tesla-using-samsung-sdi-battery-cells-129-mwh-south-australia-facility/

https://www.google.com/amp/s/reneweconomy.com.au/tesla-big-battery-moves-from-show-boating-to-money-making-93955/amp/

https://www.greentechmedia.com/articles/read/the-biggest-batteries-coming-soon-to-a-grid-near-you