Electronics > Power/Renewable Energy/EV's

Tesla 18650s and 21700s

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OwO:
So I just recently discovered that there are quite a few sellers offering Tesla 18650 cells on taobao, and one listing even sells around 3000pcs/month. They are advertised as NCR18650B replacements with a lower ESR, and go for cheaper than the listings offering "genuine" NCR18650B. The Tesla cells go for around 13 yen (2 USD) whereas the Panasonic ones go for 20 yen (3 USD).

I got a few (8 cells) to play with and do charge/discharge tests. There are no markings on the cell, allegedly they come without plastic wrapping originally and the green wrapper was retrofitted on. The charge capacity measured to be ~3250mAh and discharge capacity ~3150mAh. Variance between cells was low at around +/-50mAh. The charger reports an ESR of ~10mOhm when fully charged. During discharge I glanced at the cell voltage and mAh discharged so far once in a while, and compared to the NCR18650B datasheet. It seems the discharge profile is almost identical to the NCR18650B.

There are also 21700 cells listed, I might play with those once I can get a charger that it will fit in. I do wonder how these sellers got their hands on the cells, or if they are actually pulls from Tesla battery packs.

EDIT: Added photos

Nusa:
More likely they aren't Tesla batteries at all, even if they turned out to be fairly decent batteries in your tests.

What do you see if you remove the green wrapper?

Kjelt:
 Why not?
Last week Tesla and Panasonic announced to withdraw their planned investment in their mutual LiIon factory, due to lower sales of cars than expected.
They might sell their overstock, but they could be rejected batches also.

Nusa:

--- Quote from: Kjelt on April 14, 2019, 08:33:29 pm --- Why not?
Last week Tesla and Panasonic announced to withdraw their planned investment in their mutual LiIon factory, due to lower sales of cars than expected.
They might sell their overstock, but they could be rejected batches also.

--- End quote ---

No labeling.

Chinese vendor. Non-chinese battery brand manufactured only in the US (so far) and not sold directly (that I know of). That, by itself, generally means suspect fakes, bait-and-switch, or some other scheme until proved otherwise.

Not expanding isn't the same thing as exceeding demand from their car and powerwall markets. I've seen zero indication of overstock from Telsa. Or availability of factory seconds. Have you?

I'd look at Taobao if I was a Chinese reader, but I'm not. Google translate doesn't cut it there. The image posted by OP doesn't help me in the slightest.

digsys:
Been down the same path - slowly working on our next Solar EV battery pack. May stick with pouch cells though -
Same as you, dealings with Taobao have been sus, and VERY poor communications with the sellers. The cells I've tried "seem" to work, but there is NO WAY
I can install them in a car unless I know EXACTLY where they are made, and get a real certification. I've been following the 21700 news closely, but
haven't seen any "news" from 3rd parties or even Tesla yet. Watch and wait

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