Detection of corrosion within an at least partially electrically conductive housing of an electric energy storage unit. The electric energy storage unit has a positive terminal and a resistance element between the positive terminal and the housing. State of charge values of the electric energy storage unit for at least one first instant of time and at least one second instant of time are determined. An electrical isolation resistance value between the housing of the electric energy storage unit and at least one reference point for at least one third instant of time may also be determined. A first comparison of a difference of the determined state of charge values with a predefined state of charge difference value for the electric energy storage unit and/or a second comparison of the determined electrical isolation resistance value with a predefined electrical isolation resistance value for the electric energy storage unit are performed.