Abstract: Apparatus for making separator envelopes for electrical battery plates having a device for folding an ultrasonically weldable polymeric web around individual battery plates and a device for feeding filled separator envelopes to ultrasonic welding devices, The feed device being provided with two endless synchronously driven feed belts (4, 8) above and below a horizontal feed plane (H) for the separator envelopes (S) as well as symmetrically relative to a longitudinal center plane of the apparatus, which feed belts, with their loops extending parallel to the feed plane, together engage lateral portions of the separator envelopes and which continuously pull the superposed lateral margins of the separator envelopes protruding beyond the feed belts through the ultrasonic welding device.