In the early simulation, Keith? Ritter's general starting point is very similar to our original brain hole: when the cell diameter increases, the gap between them will also increase when arranged, which is beneficial to the layout of cooling pipes around the cell side;
The other design is more radical. Didn't Tesla say "battery bearing"? Then use this brain hole to spread copper anode plates with better heat dissipation capacity on both sides of the battery pack:
Anyway, the anode plate also needs to be fixed by plane structure, and these structures (see the slender square part in the figure below) are definitely enough because of reinforcement:
It should be pointed out that according to the later calculation, the second design has higher space efficiency and energy density. Therefore, unless otherwise specified, the following explanations are based on the second structure.
Bring a model? 76kWh battery pack on the 3 (although the model? 3 should not use the 4680 battery, but after all, there are physical objects, which is better), such as through Keith? Ritter's optimization, we can find that after using the 4680 battery, the volume of the energy storage part of the whole battery pack can be reduced by about 20%:
According to the idea of designing the battery arrangement, we can probably guess that the purple box in the picture probably represents the boundary of an anode copper plate. Obviously, if the energy storage part can become smaller, it will have a positive impact on the concept of "battery carrying capacity": under certain endurance conditions, Tesla can use the extra space to strengthen the body structure, and combine the weight distribution closer to the center, and the handling performance of future models should be optimized.
Furthermore, the upper output limit of the 4680 battery is slightly stronger than that of the 2 170 battery, and Tesla can build a faster and more interesting car on this basis.
Because the outer diameter of the fuselage is larger and the internal resistance is relatively smaller, the resistance of the 4680 battery to large current is naturally stronger than that of the existing 2 170 battery. This is its inherent advantage in further improving the charging and discharging performance of Tesla models. Combined with the design mentioned above, the 4680-cell battery pack can accumulate greater advantages in charging efficiency. Without delay, let's look at the results directly (initial temperature: 85℉, about 29.4℃):
Figure: Charge power-time curve of two batteries (Keith? Ritter)
Figure: Charge Power -SOC (Battery Available Capacity Ratio) curve of two batteries (Keith? Ritter)
It can be seen that the 4680 battery can always provide higher charging power under the same charging requirements (limited charging time or certain charging amount). It is undoubtedly a better choice for users who are eager to hurry.
This is actually interoperable with the high upper limit of charging power to a certain extent. Compared with 2 170 battery, the height of 4680 battery has not changed, only the bottom area has increased. With the electrode heat dissipation copper plate mentioned above, it is not difficult to imagine that more heat can be taken away inside the 4680 battery cell per unit time just by the same heat dissipation on the bottom surface. Therefore, under the same charging power, the calorific value of 4680 battery is obviously lower than that of 2 170 battery:
Translated into adults, the probability of spontaneous combustion caused by charging will also decrease. Similarly, the spontaneous combustion of vehicles due to overheating under high load should also be reduced. This should be what all Tesla owners want to see.
Anyway, from Keith? Ritter's series of calculations on the 4680 battery show that Tesla seems to be tired of the battery capacity war/energy density war, and intends to alleviate users' concerns about charging and discharging and battery safety from the hardware level. As a modern electric vehicle manufacturer with the earliest start and the richest technology accumulation, Tesla's decision is not only more grounded, but also objectively promotes technological progress. Why not do something that both sides win?
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.