There are thousands of them inside the Model S and X yet it’s one of the least understood part of Tesla’s vehicles. While Panasonic, Tesla’s battery cell manufacturers, lists the specifications of almost all its different cells, they don’t release the specs of the custom cells it developed with Tesla.

Without going into too many details, a new breakdown of a Tesla cell shows what is inside.

A Youtube channel bought 18650 cells from eBay, where the seller claims that they have been extracted from Tesla’s battery modules, presumably from salvaged vehicles.

Panasonic sells its battery cells in volume separately, but the company developed a custom cell with the 18650 format in partnership with Tesla. Back in 2014, Tesla signed a contract with Panasonic to manufacture billions of those cells to use in the Model S and X until the end of 2017.

Of course, we now know that they developed a new cell with a bigger 2170 format to be manufactured at the Gigafactory in Nevada, but those cells are currently used for the Tesla Powerpack and Powerwall. They will also be found in the Model 3 later this year, but for now the 18650 cell is the only one used by Tesla in its vehicles.

They supposedly have a longer lifespan than Panasonic’s off-the-shelves NCR 18650 cells. The seller apparently tested them and supplied those comparison charts:

Back to the breakdown. Youtube channel Aries RC took one of those cells and removed the cap of the positive terminal to reveal the battery cell can.

They then removed and unrolled the jelly roll from the can to reveal the anode, cathode, and electrolyte.

It’s an interesting quick video: