This SAE RP provides a set of test methods and practices for the characterization of the properties of Li-battery separator. The test methods in this RP have been grouped into one of three categories: 1 Manufacturing parameters: Minimum set of separator properties to be measured 2 Chemistry/Customer specific parameters: Properties that are dependent on the application, customer needs and/or requirements, manufacturing process etc. This RP will include the current best practice methodologies for these tests, with an understanding that the best practice methodologies are evolving as more information is learned. 3 R&D parameters: Properties that are dependent on the application, customer needs and/or requirements, manufacturing process etc. The methodologies in this 3rd section are under development and have not yet achieved broad application. It is not within the scope of this document to establish criteria for the test results, as this is usually established between the vendor and customer.