Friday is here, and the "A Taste of Science for the Weekend" corner is back — number 90 💫.
This week Tesla returns for a second installment — on the groundbreaking engineering behind its battery pack and thermal management systems.
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The first electric vehicle was developed around 1830, long before Tesla.
But every attempt to build an electric car that wasn't just drivable, but also economical and reliable enough to compete with gasoline vehicles, ended in failure — due to a long list of technical challenges that only Tesla managed to solve.
Two central factors can be identified as the downfall of the electric vehicles that preceded Tesla: temperature and batteries.
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Early electric vehicles relied on a dense array of rectangular battery cells. The rectangular form allows cells to be packed tightly against one another with no gaps, maximizing energy density per unit area.
The problem with this approach was that during high-speed driving or fast charging, the batteries would heat up significantly — and because it is difficult to dissipate heat from the center of a battery pack outward, massive and inefficient cooling systems were required.
At the same time, batteries and electric motors don't generate heat the way gasoline engines do, so cabin heating systems drew heavily from the vehicle's battery pack and cut into driving range.
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Tesla replaced the rectangular cells with cylindrical battery cells (shown in the video). The cylindrical form offers greater resistance to internal pressure compared to a rectangular one, making it possible to produce thinner and lighter battery casings.
Cooling tubes are threaded through the gaps between the cylindrical cells, allowing the battery pack to be scaled up significantly and fast chargers to be used, without the problem of excessive heat buildup.
The vehicle's thermal management system was engineered for maximum efficiency. Heat generated by the batteries, the motor, and even the outside air is used to raise the cabin temperature via heat pumps, rather than relying on power-hungry resistive heating coils.
In extremely cold environments, an unconventional method is used to heat the vehicle's systems.
The electrical current flowing from the battery to the motor is modulated into an irregular pattern, causing the motor to operate with deliberate inefficiency. That inefficiency converts energy into a rapid burst of heat.
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Batteries are built from layers of rolled metallic foil sheets, through which electrons flow toward a metal tab at the end that transfers the current out to the battery's terminals. With this design, the larger the battery, the more heat accumulates inside it — because electrons travel along longer sheets and heat them as they move.
Tesla developed a new approach in which, instead of a tab at the end of the sheets, all of the rolled foil layers conduct electrons directly to the battery's top and bottom terminals. In practice, this significantly shortens the distance electrons travel inside the cell and reduces the heat generated — enabling the creation of especially large battery cells.
An additional innovation is the use of the battery pack as the vehicle's floor.
Previously, a battery pack was bolted onto an existing metal chassis floor. Tesla integrated the batteries into a rigid structural frame that itself became the vehicle's floor, saving considerable weight.
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Another aspect is the high cost of batteries and its impact on the final vehicle price.
After enormous difficulties spanning many years, Tesla succeeded in establishing its own battery manufacturing plants at a cost of billions of dollars, paving the way for mass production of affordable electric vehicles.
In the video: part of the battery manufacturing process at Tesla's factories.
Shabbat Shalom 😊
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