Battery Testing Methods · Last reviewed 2026-09-17
Three related loads: uniform compression (the stacking pressure the pack applies), swelling measurement (how much the cell grows over charge and life), and crush (the abuse case, per standard). The first two are engineering parameters; the third is a safety verdict — and the pouch cell's construction makes all three different from the rigid-can world.
The pouch cell's case is a laminated foil bag, not a metal can — which is why it achieves high energy density and why it needs external support. Unsupported pouch cells swell, delaminate their layers and lose capacity; over-compressed ones risk internal shorts. The practical consequence: every pouch pack is designed around a compression window, and the pressure test is where that window is proven.
The cell sits between pressure plates while charge, discharge and aging proceed. Two numbers are recorded throughout: the applied pressure and the thickness change. The verdict comes from the combination — a cell that stays within its swelling budget at its specified pressure passes; one that grows past it, or needs more force to stay flat, is telling you something about its chemistry or its assembly.
| Typical stacking pressure | Roughly tens of kPa for pouch cells (per cell design) |
| Swelling budget | A few percent of thickness over life, per design |
| Crush test (safety) | Defined deformation per standard, no fire / no explosion |
Design-specific values — the cell's datasheet, not the standard, sets the compression window.
Pressure behaviour is verified before pack design (cell characterisation), during design (module compression trials), and after abuse (did the crush or short leave the cell able to vent safely). It is the test that connects the cell's datasheet promise to the pack's mechanical reality — the place where soft-case physics meets hard-case engineering.
My take: The pouch cell trades its hard case for energy density and pays for it in engineering discipline — and the pressure test is where that discipline is measured. A pouch pack is only as good as the compression design its pressure data was built from.
Why: The can hides its pressure; the pouch announces it. Testing the announcement — the swelling curve under load, over life — is how pack designers convert the pouch's fragility into its advantage, and how buyers can tell a designed pack from a wrapped one.
My editorial view, not a purchasing guarantee.
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