The automotive industry is commonly set as the most important sector for electrification. It uses established and uniform procedures regarding battery management and thermal regulation. In less standardised industries, broad battery system requirements often lead to more complicated solutions with significantly lower sales figures, making it difficult for manufacturers to engineer proper systems to minimise inhomogeneities in the battery system, like equalised temperatures. Furthermore, the electrical parameters are primarily considered for state estimation of battery systems, with the temperature per cell checked once or less. Due to the enlargement in cell sizes, the occurring temperature gradients increase because of current rate inhomogeneities and the heat conductivity.
Usually, battery cells are thermally characterised by single-cell measurements, using models to calculate the temperature for battery modules. Therefore, the ambient conditions are crucial. In research, polystyrene casings with known thermal parameters are frequently used as containers for tests with minimised influence of the heat exchange with the ambient. The test setup in this work employs such a casing as the boundary condition to force more distinctive gradients.
The configuration comprises a three-cell module assembled of thermally coupled automotive-sized pouch cells. Each cell uses a separate electric connection to investigate different propagation scenarios in the stack, covering the arising gradients by the various possible power flows and the characterisation of the module behaviour. It includes thermal pulses to obtain the setup’s temperature response in the time domain and complete cycling tests to track the differences regarding the influence of the reversible or reaction heat.
The purpose lies in investigating built modules in real-world applications without knowledge about the individual cells, reducing the measurement efforts needed to track hot spots in such cell arrangements. Another benefit is the identical ambient condition in both significant directions for the inner cell in the module for further single-cell investigations.