Apparatus and method for testing the insulation of a cell module assembly and testers for

An apparatus for checking insulation of a cell module assembly (200), which is composed of a plurality of pocket cells (100), the apparatus comprising: a first tester means (310) which is connected electrically with an electrode of the cell module assembly (200); a second tester means (320) which is electrically connected with aluminum films of several selected pocket cells (100) in the cell module assembly (200), said second tester means (320) comprises at least one groove (321) and the aluminum films of the plurality of selected pocket cells (100 ) are connected to the groove (321); and a measuring means (303) for measuring an insulation resistance between the first tester means (310) and the second tester means (320).