Tesla cars
Figure 5- Parts of a lithium-ion battery ( How does a lithium-Ion battery work? n.d.)
Figure 5 shows the lithium-ion battery set up in a similar way to how Volta’s original battery was created.
By using lithium and graphite instead of zinc and silver, the average lithium-ion cell has a voltage between 3-4.2 volts (Lesics, n.d.). Compare this to the original zinc and silver cell at 1.6 volts and the
power output by lithium-ion batteries far outranks that of the zinc and silver cell batteries. So far, the lithium-ion battery is the most advanced battery technology that exists. Scott K. Johnson (Johnson, 2020) claims that the graphite in lithium-ion batteries contributes a substantial amount of volume and weight, while not ‘directly’ contributing to energy storage, other t han to keep the cell working. What Tesla and a few other manufacturers do is to add silicon inside the graphite, allowing the same volume of graphite to physically hold more lithium, creating a larger energy density in every cell. Tesla is also improving on its cathode technology and is using multiple chemistries to provide three types of lithium-ion batteries. These batteries will fit three different price points which depend on the economic and technological needs of a certain car type.
Battery management system (BMS)
What also makes Tesla battery packs superior to many other electric car brands is their battery management system. In the recent model X and S, each battery consists of six cells in series and a variable number of cells connected in parallel (between 40-80) depending on the model. In total, a module can have almost 500 cells and a battery powerpack consists of 16 of these modules. When functioning, the cells will produce a lot of heat and high temperatures which can cause the cells to decay. To solve this i ssue, Tesla’s battery management system manages temperature, each individual cell’s state of charge, voltage protection and cell heath monitoring. To regulate temperature, Tesla has a glycol cooling system. Depending on the temperature of the cells, the BMS will adjust the glycol flow rate to maintain the perfect temperature for cell performance. While water is a good coolant, there are several safety issues which make glycol a better alternative to use in a high voltage cell (Miller, 2020). One of these is that if conductive water leaks inside the batter, it may cause loss of insulation. This can lead to safety hazards, such as the potential for an electric shock. To maintain voltage protection, BMS carries out the process of cell balancing which ensures that all the cells charge and discharge equally. If one cell is more charged than another while charging, then some of the cells may ‘overvoltage’ which creates excessive voltage stress and will degrade the battery. Lesics (Lesics, n.d.) claims that it is these reasons which make Tesla technology better than other companies like Nissan. Nissan has a huge battery cooling issue due to their big cell design, paired with an insufficient cooling method. By using thousands of much smaller cells, rather than fewer larger ones, Tesla saves heavy battery strain which would decrease the lifespan of their batteries, thus making the correct decision for maximum power output.
214
Made with FlippingBook interactive PDF creator