A common grouping of cells that can be built as a sub-assembly and be replicated many times to form a total battery pack. Normally this will include:
- Cells in series and parallel
- Electrical interconnects between cells
- Voltage sense harness
- Temperature sensors
- Local control board for sensing
- Mechanical system to hold all of the cells – for pouch and prismatic cells the module will need to apply pressure over the lifetime of the cells to support their operation.
- Heating/cooling interface
The move towards larger modules and now cell to pack design is changing how modules are viewed by the large vehicle OEMs. However, in most other industries a robust modular based battery pack design has benefits that are difficult to give up. One area is servicing where a common building block can significantly reduce the overall cost.
Modules in the 2019 Porsche Taycan
A key aspect of the thermal design is the connection between the cell and the cooling system. The interface between a hard cased cell and a cooling plate will need some form of thermal interface material that can connect the two.
It is really important that this material maintains that thermal interface over the lifetime of the product.
The capacity and resistance differences of cells amplify the inhomogeneity at a system level and results in accelerated aging and degradation.
For the module design, where many cells are in parallel, the BMS typically does not have access to individual cell currents and temperatures.
We aim to predict current, state of health and temperature of each cell in the module (or pack) via modelling the interaction between cell and busbar and weld quality.
There are 7 Steps in the Module Production Process:
- Incoming Cells Inspection
- Stacked Cells Tightening/loading with End Plates
- Connecting the Cells inside the Module
- Mounting of the BMS Cell Sensing Circuit (CSC)
- Cell Stack is Loaded into Module Housing
- End of Line Testing and Quality Control of the Module