Pack Mechanics - Battery Design

The mechanical design of a battery pack needs to consider every element of the system. You need to look at static stiffness, dynamic stiffness and behaviour of components.

For the design of the 2019 Porsche Taycan the battery housing is a load-bearing component of the body structure:

truss-design battery frame with multiple subdivisions
28 bolts fix the battery to the body structure
battery contributes ~10% of the vehicle’s overall stiffness

Other automakers take a very different structural approach: the Cybertruck battery pack structural analysis looks at how that pack carries load. Enclosure material choice feeds into the same stiffness and weight trade-offs — see Magnesium as a Battery Enclosure Material for an alternative to the more common aluminium and steel enclosures.

Battery to Vehicle Mechanical Integration

The mechanical structure of the battery is one thing, but we need to consider battery to vehicle mechanical integration. The total vehicle unladen weight can be around 2000kg and the battery pack can be 500 to 600kg and hence a significant portion of the overall weight.

Maintaining mechanical integrity, but ensuring electrical and thermal isolation can be challenging.

When looking at the mechanics of the pack it is important not to forget the busbars and control cables. These need to be secured and isolated.

Sealing

Needs to be considered across the components and at a system level.

Venting

Rupture Disc Integration for Overpressure Mitigation

Sizing rupture discs for Li-Ion battery packs presents unique challenges due to varying battery chemistries, sizes, and configurations. Unlike conventional applications, there isn’t a one-size-fits-all formula for rupture disc sizing in battery systems. To ensure the relief area of a rupture disc is sufficient for the battery enclosure and cell configuration, thorough testing is essential.

Welding

From welding tabs onto electrodes to stir welding aluminium pack enclosures there are so many areas where welding is used within a battery pack.