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.

This means that it not only has to be connected securely to the vehicle structure (see our rundown of different battery tray designs for how that connection is usually made), but also the structure of the battery needs to work with the vehicle structure. Otherwise, carrying a dead weight of 500 to 600kg feels like a missed opportunity.

The Audi Q6 body and battery structure are orthogonally aligned.

The body of the Q6 has significant structure around the perimeter of the pack. At the front the structure is required to spread the frontal crash forces into the sills on the body and the fore-aft beams in the battery pack. The beams across the floor of the body between the sills are there to protect the occupants and battery from side pole crash.

It is important to note that the stiffness of the battery pack can be very high and thus careful consideration must be made with respect to build tolerances. Otherwise the pack could deform the body during assembly.

Cell to Pack

This is all about reducing cost and increasing the volumetric density of battery packs (see our breakdown of cell to pack volume ratio for how that density gain is actually measured). This is primarily aimed at road vehicle battery design. This can offer some significant increases in energy density and cost reductions. However, this does remove barriers between cells and hence brings into focus the task of how to stop cell to cell propagation.

Cell to Body

A step on from Cell to Pack and integrates some of the vehicle body parts and functions into the pack and vice versa.

Needs review: the Cell to Body section above is a placeholder-length summary compared to the Cell to Pack section next to it. It could use a fuller explanation of how body-integrated pack designs affect crash load paths and serviceability, ideally with a named example vehicle for the reader to reference.