The new Xpeng Sepa 2.0 platform debuts on the new G6 EV. We will look at the G6 battery packs in more detail in later posts, but for now it is worth looking at the platform. Especially as this is another cell to body design.
SEPA = Smart Electric Platform Architecture
When this new platform was presented back in April 2023 [2] the details were few and far between. The release of the G6 has given a few more details.
Cell to Body
We have seen cell to pack battery designs from BYD and CATL. BYD with their ground breaking Blade design has brought LFP chemistry back into the world of EV’s.
The next step is to place the cells directly into the vehicle body structure: Cell to Body or CTB or C2B. At first you might think that this is just the next obvious step, however, there are a number of questions around manufacturing, repair and service that we need to understand.
The claims are substantial:
- Body torsional stiffness = 41,600 Nm/degree
- 83% increase in torsional stiffness
- 161 integrated components
- 17% reduction in vehicle weight
- 5% increase in vertical space
- 800V architecture
This post has been built based on the support and sponsorship from: Thermo Fisher Scientific, Eatron Technologies, About:Energy and Quarto Technical Services.
Maybe a subtle play on words here as XPENG describe this as Cell Integrated Body. This does look like other CTB designs in that there is a pack frame along with lower and upper closure panels.
The key is perhaps that the body doesn’t have a floor panel as it uses the upper battery closure for that purpose.
There appears to be substantial beams across the pack at each end and across the centre. The end beams also appear to be supported by the curved pack frame. Our assumption is that these support cell compression requirements and cross-car side impact.
In addition there are two fore-aft battery beams in addition to quite substantial sill structures.
In this next charging image you can see the distance between the cells in the centre is quite substantial. Space for a large amount of structure to support the B-posts in the body.
The battery is integrated as a fixed part of the platform. A 3-layer anti-collision structure helps protect the battery, and the side pillar can withstand a pressure of up to 80 tons. Because of all this, we achieve a vertical space saving of 5%. It provides a much better driving experience and a more spacious cabin.
In this next image you can see the open floor pan design.
Using the latest gigacasting techniques, the G6 has a front and rear cast in one piece of aluminum which provides far better electrical performance. More than 300 parts are integrated into one to provide greater resistance, better weight management. In addition to lower weight and thus longer range, it also means that the car is safer and provides better protection, as the whole vehicle torsional stiffness is up to 41,600 Nm/deg, which is an increase in body torsional stiffness of 83% compared to our previous designs.
This is very much a body and battery design that has been achieved by working as one team.
There is a lot more to understand with regards to this battery design. We know it is an 800V platform, it uses a heat pump and that the cells are heated and cooled on the top surface.
References
See also: Battery to Vehicle Mechanical Integration, Pack to System Mechanics, Blade Cells