Multiple testing methods are herein presented to quantitatively, deterministically and non-destructively leak test prismatic or cylindrical lithium-ion battery cells. At this time no test method has been codified for finding small leak channels in the battery cells. While the minimum detection limit of the available test methods has yet to be determined, the methods detailed in this paper have been demonstrated to effectively find leaks that are common in automated cell manufacturing lines. The nature, cause and approximate size of the defects are described in this paper along with the methods shown to be effective in testing for them.