Look at the battery design of Model 3 from Tesla's completely closed ecology

Lithium Grid News: Tesla’s factory is about to be built in Lingang. As mentioned in the previous article, a very realistic question. Most consumers and leaders will ask, 'Your domestic new energy What should auto companies do? Yes, including traditional auto companies and emerging car manufacturers, what do you do?” Not to mention that Tesla has completely surpassed Tesla. force.

Each of us has limited abilities. We can only come up with something that can compete with it in a limited number of links. However, from the overall situation of Tesla, one is that we are not in all links. Those who stop are burning money, and those who keep improving. Therefore, even if a single product, from Porsche's Mission E, Audi's Etron, and Jaguar's Epace, is truly matched, it is difficult to say that there is a product of the same type that directly rivals it.

For Model 3 power batteries, several domestic companies are doing research and analysis. I think this is a question worthy of long-term discussion, so I have written several articles before and after. My thinking has always been to choose a suitable time to make some introductions at a few points, and then I will update when I have more resources.

1) System configuration

This picture is taken from the PPT made by Boqi Wang. From the perspective of the assembly, it is divided into modules and trays. And power electronics and BMS.

The length of this system structure still exceeds our expectations.

We match this system structure with the previous battery production problem. The problem may really be in the module design, while in Zone3 and Zone4, it may be biased towards the whole System assembly, and there are some assembly problems in the front-end module assembly.

2) Module design

At present, our verification center is to make so many cells into a digital model to evaluate this model. The characteristics of the group, especially the requirements for shock, vibration and structural characteristics. The safety verification content includes: impact (UN3480), extrusion test, module condition under side impact, exhaust characteristics, thermal runaway condition of the unit, and module drop.

Due to the lack of adequate partitions in the entire shell, the analysis of this structure deserves our follow-up careful shock.

Here is a process of measurement and calculation, which is based on the distance between the cells. This requires the measurement of the tolerance range after the physical object is disassembled

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I roughly made some estimates:

The two module specifications measured the following data:

According to the layout of the module, there are 14 columns inside

It can be converted to the module, which requires a total of 76 rows and 82 rows, and It is not divisible. There are some fake cells in the cells to support the whole part.

After the spacing is calculated, the actual arrangement inside is indeed very tight:

As shown in the figure below

The energy of 21700 is larger than that of 18650. According to this distance, I will do puncture or heat to cause thermal runaway. The probability of this propagation is actually higher than before.

Note: Compared with the previous one, the propagation direction may be more single. It may be more intuitive to reproduce the heat transfer path if you get some samples.

3) Busbar and FPC

Look carefully, in the process of busbar isolation:

Using a plastic bracket, This busbar is isolated by a plastic bracket and kept isolated from other battery core shells.

Next, we have to spend our energy to study FPC. In the large module design, we use this cable fpc design to make the entire wiring It's easy. In the module, on the basis of the connection and support structure with the module, the line is replaced with FPC, and there are still advantages in overall assembly and error-proofing.

Summary: I try to take a closer look at the real thing once, so that I can have an intuitive understanding of the design.