Greater capacity, greater power, smaller size, lighter weight, easier mass manufacturing, and the use of cheaper components are challenges in designing EV batteries.In other words, it boils down to cost and performance.Think of it as a balancing act, where the kilowatt-hour (kWh) achieved needs to provide maximum range, but at a reasonable cost to manufacture.As a result, you’ll often see battery pack descriptions listing their manufacturing costs, along with numbers, ranging from $240 to $280/kWh during production, for example.
Oh, and let’s not forget safety.Remember the Samsung Galaxy Note 7 fiasco a few years ago, and the EV battery equivalent of vehicle fires and Chernobyl equivalent meltdowns.In a runaway chain reaction disaster scenario, spacing and thermal controls between cells in a battery pack to prevent one cell from igniting another, another, etc., add to the complexity of EV battery development.Among them, even Tesla has problems.
While an EV battery pack consists of three main parts: battery cells, a battery management system, and some sort of box or container that holds them together, for now, we’ll just look at batteries and how they’ve evolved with Tesla, but Still a problem for Toyota.
The cylindrical 18650 battery is a lithium-ion battery with a diameter of 18 mm, a length of 65 mm and a weight of approximately 47 grams.At a nominal voltage of 3.7 volts, each battery can charge up to 4.2 volts and discharge as low as 2.5 volts, storing up to 3500 mAh per cell.
Much like electrolytic capacitors, Tesla’s electric vehicle batteries consist of long sheets of anode and cathode, separated by charge-insulating material, rolled up and tightly packed into cylinders to save space and store as much energy as possible.These cathode (negatively charged) and anode (positively charged) sheets each have tabs for connecting similar charges between the cells, resulting in a powerful battery—they add up to one, if you will.
Just like a capacitor, it increases its capacitance by reducing the spacing between the anode and cathode sheets, changing the dielectric (the above insulating material between the sheets) to one with a higher permittivity, and increasing the area of the anode and cathode The next step in the (power) Tesla EV battery is the 2170, which has a slightly larger cylinder than the 18650, measuring 21mm x 70mm and weighing around 68 grams.At a nominal voltage of 3.7 volts, each battery can charge up to 4.2 volts and discharge as low as 2.5 volts, storing up to 4800 mAh per cell.
There’s a trade-off, however, that’s mostly about resistance and heat versus needing a slightly larger jar.In the case of the 2170, the increase in anode/cathode plate size results in a longer charging path, which means more resistance, thus more energy escaping from the battery as heat and interfering with the fast charging requirement.
To create a next-generation battery with more power (but without increased resistance), Tesla engineers designed a significantly larger battery with a so-called “tables” design that shortens the electrical path and thus reduces the amount of heat generated by the resistance .Much of this can be attributed to who may be the best battery researchers in the world.
The 4680 battery is designed in a tiled helix form for simpler manufacture, with a package size of 46mm in diameter and 80mm in length.Weight is not available, but other voltage characteristics are reported to be similar or identical; however, each cell is rated at around 9000 mAh, which is what makes the new Tesla flat-panel batteries so good.Also, its charging speed is still good for fast demand.
While increasing the size of each cell rather than shrinking may seem to go against the battery’s design requirements, the improvements in power capacity and thermal control of the 4680 compared to the 18650 and 2170 resulted in substantially fewer cells compared to using the 18650 and 2170 Battery-powered earlier Tesla models have more power per battery pack of the same size.
From a numerical standpoint, this means that only about 960 “4680″ cells are required to fill the same space as 4,416 “2170″ cells, but with additional benefits such as lower production costs per kWh and using 4680 The battery pack increases power significantly.
As mentioned, the 4680 is expected to offer 5 times the energy storage and 6 times the power compared to the 2170 battery, which translates to an expected driving increase from 82 kWh to 95 kWh in newer Teslas Mileage increases by up to 16%.
Remember, this is just the basics of Tesla batteries, there is more behind the technology.But this is a good start for a future article, as we’ll learn how to manage battery pack power usage, as well as control the safety issues around heat generation, power loss, and… of course… the risk of EV battery fires.
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Timothy Boyer is a Tesla and EV reporter for Torque News in Cincinnati.Experienced in early car restoration, he regularly restores older vehicles and modifies engines to improve performance.Follow Tim on Twitter @TimBoyerWrites for daily Tesla and EV news.
Post time: Feb-21-2022