Energy storage device for a motor vehicle, comprising - a first energy store having a first electric positive pole and a first electric negative pole and a second energy store having a second electric positive pole and a second electric negative pole for storing electric energy; - a charging connection for charging the energy stores (2, 3); - an operating connection for the operation of a load at the energy storage device; and - a switching device which comprises a plurality of switching elements (S1-S7) and by means of which the energy stores (2, 3) can optionally be connected in series or in parallel, wherein a fifth switching element of the switching device is permanently connected electrically to the electric poles (4, 5, 6, 7) of opposite polarity of the energy stores (2, 3) and the energy stores (2, 3) can be connected in series with the fifth switching element, characterised in that - by means of a first switching element a positive pole of the operating connection can be electrically decoupled from the positive poles (4, 5) of the energy stores (2, 3), and - by means of a second switching element a negative pole of the operating connection can be electrically decoupled from the negative poles (6, 7) of the energy stores (2, 3), and - by means of a third switching element a positive pole of the charging connection can be electrically decoupled from the positive poles (4, 5) of the energy stores (2, 3), and - by means of a fourth switching element a negative pole of the charging connection can be electrically decoupled from the negative poles (6, 7) of the energy stores (2, 3), wherein the third and/or the fourth switching element (S3, S4) are designed as battery contactors or charging contactors, and wherein a sixth switching element is electrically located between the first positive pole of the first energy store on the one hand and the first switching element and the third switching element as well as the second positive pole of the second energy store on the other hand, and a seventh switching element is electrically located between the second negative pole of the second energy store on the one hand and the first negative pole of the first energy store as well as the second switching element and the fourth switching element on the other hand, so that the fifth, sixth and seventh switching elements (S4, S6, S7) facilitate a parallel or series connection of the two energy stores (2, 3), by providing that the two energy stores (2, 3) are connected in series if the fifth switching element is closed and the sixth and seventh switching elements (S6, S7) are open, and that the two energy stores (2, 3) are connected in parallel if the sixth and seventh switching elements (S6, S7) are closed and the fifth switching element is open. - a first energy store having a first electric positive pole and a first electric negative pole and a second energy store having a second electric positive pole and a second electric negative pole for storing electric energy; - a charging connection for charging the energy stores (2, 3); - an operating connection for the operation of a load at the energy storage device; and - a switching device which comprises a plurality of switching elements (S1-S7) and by means of which the energy stores (2, 3) can optionally be connected in series or in parallel, wherein a fifth switching element of the switching device is permanently connected electrically to the electric poles (4, 5, 6, 7) of opposite polarity of the energy stores (2, 3) and the energy stores (2, 3) can be connected in series with the fifth switching element, characterised in that - by means of a first switching element a positive pole of the operating connection can be electrically decoupled from the positive poles (4, 5) of the energy stores (2, 3), and - by means of a second switching element a negative pole of the operating connection can be electrically decoupled from the negative poles (6, 7) of the energy stores (2, 3), and - by means of a third switching element a positive pole of the charging connection can be electrically decoupled from the positive poles (4, 5) of the energy stores (2, 3), and - by means of a fourth switching element a negative pole of the charging connection can be electrically decoupled from the negative poles (6, 7) of the energy stores (2, 3), wherein the third and/or the fourth switching element (S3, S4) are designed as battery contactors or charging contactors, and wherein a sixth switching element is electrically located between the first positive pole of the first energy store on the one hand and the first switching element and the third switching element as well as the second positive pole of the second energy store on the other hand, and a seventh switching element is electrically located between the second negative pole of the second energy store on the one hand and the first negative pole of the first energy store as well as the second switching element and the fourth switching element on the other hand, so that the fifth, sixth and seventh switching elements (S4, S6, S7) facilitate a parallel or series connection of the two energy stores (2, 3), by providing that the two energy stores (2, 3) are connected in series if the fifth switching element is closed and the sixth and seventh switching elements (S6, S7) are open, and that the two energy stores (2, 3) are connected in parallel if the sixth and seventh switching elements (S6, S7) are closed and the fifth switching element is open.