Statistical Sampling Plans for Incoming Prismatic Lithium Cell Shipments
Incoming prismatic cell sampling relies on ISO 3951-1 variable plans and ISO 2859-1 attribute plans to reject defective lots before module integration.
Hypergeometric Distribution
Meaning
Probability model that describes the number of successes in a sequence of draws from a finite population without replacement. Use of the hypergeometric distribution is standard in battery lot acceptance testing where the removal of a sample changes the probability of the next draw. Unlike binomial models, this distribution accounts for the decreasing size of the remaining batch.
Statistical Logic
Calculations determine the likelihood of finding a specific number of defective cells in a sample size taken from a known total quantity. When a manufacturer produces a lot of ten thousand units, the hypergeometric distribution provides the exact risk of accepting the batch if it contains a given number of nonconforming items. Precise modeling is necessary for high risk components where failure could lead to thermal runaway.
Variable Relationship
Parameters for the formula include the total population size and the number of successes along with the specific sample volume.
Quality Threshold
Application of this model sets the thresholds for supplier audits and incoming inspections. If the number of failures in the sample exceeds the calculated limit, the entire shipment is rejected. This method ensures that the consumer risk and the producer risk stay within agreed limits.