Electric plug-in connector for portable electrical energy storage unit

The energy storage device is mounted in a housing with narrow sides (L), a plug holder (SA) on one narrow side with vertical guides for a plug and contact surfaces near the guides for electrically connecting the energy storage device and plug. The plug (SS) has a gripping arrangement complementary to the guides for fixing the plug with respect to the housing in the contact position and counter contacts for connection to the contact surfaces. An Independent claim is also included for an electrical energy storage device.