However, a closer look shows that for leak testing, throughput is often an even more important variable than pure cycle time. Throughput during testing can be decisively increased by a batch testing approach.
Let's assume that batches of 16 round cells of type 21700 each are to be tested in the described system with an external vacuum pump and with DMC as the essential solvent. With a cycle time of 22 s, this results in a test time of 1.4 s for each cell. If the batch is enlarged to 64 round cells, one cell is tested every 0.3 s. If a batch test reveals a leak, the leaky cell must be identified at a manual test station. To do this, the batch size is halved several times so that the batch that does not contain the leaking cell can always be ignored for further tests. Thus, in an iterative way, one approaches a batch of size 1: i.e., the one that contains the defective cell. With 16 cells in the original batch, this principle results in four further test stages; with 64 cells, six stages are necessary for separation.