Method and control device for electrically charging an energy storage of a motor vehicle

A netgid for electrically charging an energy storage of a motor vehicle at an electrical energy source external to the vehicle, from a specific initial charge state of the energy storage to a specific final charge state of the energy storage, comprising:

• in the event that a first charging mode is set, a control device controls the charging according to the first charging mode such that the energy storage is charged by the external energy source from the initial charge state to the final charge state with a first charging power and according to a first overall efficiency which relates to the ratio of a first amount of energy stored in the energy storage during charging from the initial charge state to the final charge state to a second amount of energy obtained from the energy source,
• wherein the control device checks whether an activation request made by a user to activate a second charging mode, which represents an energy saving mode, has been received, and
• under the first condition, that the control device determines that the activation request has been received, the control device activates the second charging mode and controls the charging process according to the second charging mode such that the energy storage is charged by the external energy source from the initial charge state to the final charge state according to a second overall efficiency which is higher than the first overall efficiency and lower than a specific maximum possible overall efficiency.