A device (70) for the ascertainment of a status of the thermal connection of at least one electrical energy storage unit (15, 16, 17, 18) within an electrical energy storage system (10) to a heat source or heat sink, wherein the electrical energy storage system (10) comprises the at least one electrical energy storage unit (15, 16, 17, 18) comprising an electronic battery management control device (72) that is configured to
- ascertain (S11, S21, S31, S32, S41) a temperature of the at least one component;
- ascertain (S12, S22, S33, S42) a temperature of the heat source or heat sink;
- and
- ascertain (S13, S23, S34, S43) a status of a thermal connection of the at least one component to the heat source or heat sink on the basis of the temperature of the at least one component and of the temperature of the heat source or heat sink.