Abstract: The invention relates to a method for filling a battery or accumulator foil bag with fluid and sealing said bag, comprising the steps: a) providing a flexible foil pouch in the interior of which the solid components (8; 31) of the battery and/or accumulator are accommodated, wherein the foil pouch is tightly sealed with the exception of a sealable opening (11, 12) accessible for fluid, b) situating the foil pouch in a gas-tight sealable chamber (21) and gas-tight sealing of the chamber, c) following step (b), applying a vacuum in the foil bag, d) connecting the fluid access port on the foil pouch to a fluid source reservoir (17) via a connecting tube (14; 29), forming a tight seal, e) following step (d), completely filling the pouch interior with fluid via the connecting tube and f) hermetically sealing the foil pouch by placing a seam (10; 36), wherein either (i) the seam is placed such that the fluid access port connected to the connecting tube is separated from the interior of the foil pouch and the co