A vehicle electrical system includes a first partial electrical system having a first energy store of a first nominal voltage level, a second partial electrical system having a second energy store of a second nominal voltage level, and a DC-DC converter between the two partial electrical systems. The first energy store has a housing, which has at least a first tap for the first nominal voltage level, and by which a first DC-DC converter can be electrically supplied. The housing has at least a second tap for the second nominal voltage level, by which the second energy store can be electrically supplied. The housing further includes a voltage conversion unit, by which the voltage of the first nominal voltage level can be converted into voltage of the second nominal voltage level.