Posted on March 05, 2017 by Matt Pressman
We recently took a look at the new 2170 battery cell being developed by Tesla [NASDAQ: TSLA] and Panasonic. The 2170 battery will be used in the new Tesla Model 3. However, over the past few years Tesla has been using Panasonic's 18650 battery cell in its Model S and X. The 18650 battery cell is also commonly used in laptops and other everyday electronic devices. But, its use in an electric vehicle requires thousands of these battery cells to be housed in a unique arrangement, complete with control electronics and a sophisticated cooling mechanism, inside the floorpan of the car.
Above: Beginning the teardown of a Tesla Model S battery pack (Images: Jalopnik / Hackaday*)
This past week, we got an inside look into a Tesla Model S battery pack. According to Hackaday*, "Tesla famously build their battery packs from standard 18650 lithium-ion cells, but it’s safe to say that the pack in the Model S has little in common with your laptop battery. Fortunately for those of a curious nature, [Jehu Garcia] has posted a video showing the folks at EV West tearing down a Model S pack from a scrap car, so we can follow them through its construction."
Above: Tesla battery packs have longer life and lower degradation because of their ultra-efficient cooling system in which a rectangular tube runs through each battery pack module in the shape of a serpentine (Image: Synergy Files)
So what's inside a Tesla Model S battery pack? "The chassis and outer cover are held together by a huge array of bolts and Torx screws... Under the cover is a second cover that is glued down, this needs to be carefully pried off to reveal the modules and their cells. The coolant is drained, and the modules disconnected. This last task is particularly hazardous, as the pack delivers hundreds of volts DC at a very low impedance. Then each of the sixteen packs [modules] can be carefully removed. The packs [modules] each contain 444 cells, the pack voltage is 24 V, and the energy stored is 5.3 kWh."
Above: Tesla Model S battery teardown (Youtube: jehugarcia)
Jalopnik* notes, "The Tesla battery pack is something of a triumph of packaging. The battery pack is integrated into the skateboard-like chassis of the car, making a self-contained drivetrain-and-energy-storage unit that allows for really flexible body packaging... There are multiple layers of aluminum skin, moisture shields, and even some sort of blue fluid they call 'Tesla Soup' that must be extracted. This process looks tedious and involved, but it’s all worth it once you get to those sweet, juicy battery packs inside."
Above: Tesla cooling tube (Image: Synergy Files)
For more, check out another brave do-it-yourself'er, Jack Rickard, as he looks into a Tesla Model S battery pack below. In the video, he takes a deep dive into an individual Tesla Model S battery module with special attention to the battery management board. It appears that he's figured out the protocol to address individual boards in a series of up to 63 modules and gather the voltages (and temperatures) of the individual cells. Check it out below...
Above: Jack Rickard of EVTV dives into a Tesla battery pack (Youtube: Jack Rickard)