Global planning and thinking on the GM Ultium platform

The epidemic has actually had a big impact on GM's business in China, but the good news is that SAIC-GM's Cadillac LYRIQ's first pre-production vehicle was officially rolled off the production line at the Cadillac plant.

From 2021 to 2022, GM is under a lot of pressure on the volume of electric vehicles, and even was thrown out by Ford in North America. So GM Queen Mary Barra said that GM's stock portion of executive compensation is tied to the company's electric vehicle goals (the number and launch time and quality of electric vehicles in North America), 2 million units by 2025, and whether it can launch a $30,000 vehicle in 2027, really concerns the lifeline of GM.

What's particularly interesting here is that the design around this battery cell and the follow-up module and Pack cover the low-end entry-level FWD front-drive model (small car), the RWD rear-drive model (medium-sized) and the long wheelbase (first-class model), respectively; then consider the CTC design pickup and SUVs, as well as the low-top pure electric sports car design. There is more content, let's first expand the content that can be seen in China, which is two important runners.

Figure 1. GM's product line for electric vehicle platforms

My understanding is that GM was developed around the soft package design at the beginning, and then adopted the mod design method to be compatible with the needs of Chinese square shell batteries. Under the three needs of cars, medium-sized SUVs and sports cars (Low Roof), to package battery production into the package - this is in line with the current US economic & industrial policy to do a long-term huge investment model to do transformation.

Figure 2. Single-cell design pattern

Part 1 Battery level and module planning

Due to the single-cell mode, it is equipped with a battery system of the same width, different length and different thickness, and the following amount of power is calculated from the planned 1/3C power, and there is a difference between the Chinese version of the 1C charge-discharge square shell battery.

Figure 3. Configuration of GM Ultium batteries

Note: If we use the 4680 single-cell mode, the following configurations will be easier and more optimized in terms of balancing capacity and voltage.

● Low battery mode (shortest length L1, thickness H1)

6 modules (50kWh) and 8 modules (66kWh), which are the minimum configuration of 50kWh batteries, using 2P12S modules (voltage is 48V), 6 modules configured as 2P72S 300V battery packs; 8 modules configured into 400V mode. Both battery packs are for low-cost batteries

● Medium mode (normal length L2, thickness H1)

10 modules (84kWh) are configured using a 3P8S 32V battery module to form a 330V battery as a battery configuration for a medium-sized SUV

● Standard power mode (regular length L3, thickness H1)

12 modules (100kWh, China is 95.7kWh), using 3P8S 32V battery module to configure, the whole package voltage of 400V 3P96S, is a relatively efficient configuration, used in luxury cars

-- The 10 module and the 12 module are for the front drive and the rear drive (including the four wheel drive), respectively, so the difference between the two wheelbases must also be considered, which brings the problem that the energy of the front drive is difficult to further improve.

Figure 4. Consideration of both the FWD and RWD models

● 16, 20, 24 modules (integrated length L4, thickness is H2)

All three are in CTC mode, used on medium and large SUVs and pickups, and are also divided into 400V platforms and 800V platforms, and there are a lot of interesting designs here.

●Others include: A 110mm battery pack with a length L5 thickness of H3, which is for a sports car, we will introduce it tomorrow.

As shown above, there are many kinds of battery configurations in a battery platform, and I think it is indeed a bit complicated.

It is precisely because of so many changes that the cell from 400-750Wh/L of volume energy density to stacked up to become a matrix reduced by 1-20%, the module group is reduced by 15%-25%, the module and battery pack height loss is 10-20%, the overall XY layout is lost by 10%, and the final energy density is only 200-275Wh/L. Frankly speaking, compared with China's long knives, short knives, and Kirin batteries, at least from the perspective of layout efficiency and cost structure, there is no great advantage.

Figure 5. The energy density of the battery cell to the energy density of the whole package

The interesting place here is that the wireless wBMS objectively allows the general can change the module in this way, remove the communication line, and the group effect brought by the CMU is still relatively good.

Figure 6. Battery BMS management configuration, consideration between different modules

Part 2 Generic soft pack and square shell comparison

Soft bags and square shells are used here, most not least because of the particularity in China that square shells must be present. In the United States, four battery soft pack factories have been smashed, which is still very resolute.

Figure 7. Two different configurations

The more valuable here is shown in the figure below, in all aspects of the package layout, cooling and wireless connection compatibility.

Figure 8. The soft package is designed with a water-chilled plate

Since the goal of design and development has been shortened from the original 50 months to 26 months, it is still worth paying attention to whether the models can be exploded in the back, and the reduction here is the model and engineering development, and these two links have been completely shortened.

Figure 9. Changes in the development cycle of GM

Because GM sets a very low price expectation for the battery, the battery cell is required to be within 100 US dollars per Wh, and it is not known whether it can be kept under today's battery material system.

Figure 10. Battery cell price expectations

Because the investment and upstream of this battery has been supported by the official united States, the transformation and investment in North America is still very smooth.

Figure 11. Investment in battery factories

Summary: I sincerely hope that GM can make some weather, purely in terms of the group efficiency and other data seen so far, it can only be said that the original goal has been achieved, and compared with the Chinese scroll kings who are now pursuing the ultimate, they are still not cruel enough to themselves. It should be directly on the soft pack of CTP.