The module is a group of cells, traditionally a physical unit that can be transported to enable a lower cost service and repair of the battery pack.
As automotive battery packs have developed the number of modules has reduced in a drive to reduce weight, volume and cost.
However, it is still useful to think in modular terms if just as a repeatable assembly unit.
- Control
- Electrical
- Mechanical
- Safety
- Thermal
Benchmarking
What parameters should we compare when benchmarking modules? We have a Module Database that can now be downloaded.
Control
Cell voltage and temperature sensors are normally integrated into the module.
Electrical
The battery cells in a module need to be electrically connected in parallel and series.
Resistance Increase with Single Side Busbars
The single side busbar uses the cell cap as the positive (+ve) connection and the cell shoulder as the negative connection. This brings the cell to cell connections all one end of the cell, thus freeing up the mechanical and thermal interfaces. However, the negative electrical path is now through the wall of the can.
Mechanical
For blade, prismatic and pouch cell formats the cells need an external pressure applied to the case. This pressure is required for performance and lifetime requirements. In addition the module needs to mechanically fix the cells.
Cell Electrode Pressure and Expansion
The cell electrode pressure and expansion feels like two conflicting areas that have to be managed to enable performance over lifetime.
Compression pads are used to manage the dimensional change of the cell during the breathing process and for the gradual permanent swelling that occurs throughout the battery lifetime.
Safety
Cell to cell propagation needs to be considered within the module design.
Thermal
In most module designs the thermal control is external to the module, fixed down to a cooling plate with thermal interface material between them.
See also: Thermal Propagation, Cooling Plate Design