Method for operating an electrical energy storage device for a motor vehicle, and corresponding energy storage device

A method for operating an electrical energy storage device for a motor vehicle, comprising:

• equipping the energy storage device with an energy storage unit, which has an energy storage unit voltage during normal operation, and which, during a charging process, is charged by electrical energy provided at a charging connection point at a charging voltage that is lower than the energy storage unit voltage, and wherein, based on the energy storage unit voltage and the charging voltage, the energy storage unit is divided into a plurality of energy storage subunits, at least one of which has an energy storage subunit voltage that corresponds to the charging voltage and is electrically connected to the charging connection point for the at least partial charging of the energy storage unit,
• wherein the energy storage unit is divided into the plurality of energy storage subunits in such a way that the energy storage subunits each have an energy storage subunit voltage that corresponds to the charging voltage and are electrically connected to the same charging connection point for the purpose of charging the energy storage unit, or
• when the energy storage unit is divided, another of the energy storage subunits has an energy storage subunit voltage that is different from the charging voltage, wherein for the at least partial charging of the energy storage unit, this energy storage subunit is connected via a voltage transformer to the same charging connection point as the one energy storage subunit.