Battery Module Housing Mechanical Tolerances and Stack Calculations
Calculated worst-case and RSS mechanical stack tolerances govern inter-cell compression, housing deflection, bolt torque retention, and production assembly yield
Inter Cell Compression Pads
Meaning
Compressible spacers positioned between individual cells absorb volumetric changes during charging and discharging cycles. Designers install inter cell compression pads to maintain a steady mechanical pressure on the electrodes within a battery module. These sheets prevent localized stress concentrations and mechanical damage within a battery module.
They are usually made from silicone foam or polyurethane elastomers, which must resist set and compression degradation over the operating life of the vehicle. These components are chosen according to their mechanical and thermal properties.
Component Function
Squeezing foam between rigid cells protects the electrical connections from vibration damage. Sourcing high-quality inter cell compression pads ensures consistent performance under different thermal conditions. These parts also act as thermal barriers that limit heat transfer between adjacent cells.
This isolation helps prevent thermal runaway propagation across the module.
Stress Management
High mechanical forces occur when lithium-ion batteries swell as they age. Inserting inter cell compression pads allows the expansion of one cell without transferring excessive force to its neighbor. This compression prevents the metal end plates of the module from bending.
Sturdy end plates maintain the structural alignment of the entire pack.
Battery Lifespan
Constant mechanical pressure prevents the delamination of active materials from current collectors. Using optimized inter cell compression pads maintains the pressure required to minimize electrode deterioration over several thousand cycles. Gaps in pressure lead to fast capacity loss.
Proper sizing is therefore a main driver of battery durability.