NOVELTY - The energy storage system (10) has an electrical energy accumulator (12) which is provided with several series and/or parallel connected storage units (14). A control device (13) is provided for monitoring the temperature of the storage units. The control device comprises a temperature sensor (20) which has a thermal head arrangement (30) that is thermally-conductively connected to the storage units for simultaneous temperature control of the storage units.    USE - Energy storage system e.g. traction battery (claimed) for hybrid vehicle and electric car.    ADVANTAGE - The simple and yet reliable temperature control of the storage units is enabled using the control device. The temperature sensor for simultaneous temperature control of memory units, leads to more or less drastic reduction of the number of necessary temperature sensors. The occurrence of over-temperature for comparatively large number of memory units can be reliably detected and/or for a predetermined number of reliable over-temperature storage units, comparatively little temperature sensors are needed. The monitoring gaps can be reduced or eliminated. The arrester as thermal attachment location possesses good electric conductivity and good thermal conductivity. The thermal conductor made from a metallic material prevents the undesired electrical effects. The heat losses during the heat transfer can be prevented according to the elongate thermal conductor round section. The thermal ladder orientation can be formed from a metallic material, optionally with a thermal insulation e.g. made of plastic, in order to prevent and/or diminish the heat exchange between the heat conducting material and environment. The thermal ladder orientation with a multitude of nodes and multitude of stitches can be provided as a reticulated structure, which covers the memory units of the energy store to certain extent, so that material-saving and efficient heat conducting thermal ladder orientation can be achieved.    DESCRIPTION OF DRAWING(S) - The drawing shows a plan view of the energy storage system.    Energy storage system (10)    Electrical energy accumulator (12)    Control device (13)    Storage unit (14)    Temperature sensor (20)    Thermal head arrangement (30)