BMW i3, i8
Distributed E/E design
These control units provide a uniform charge for the high-voltage battery for optimum battery performance. The high-voltage batteries are always in use, due to energy consumption in electric-only driving, as well as through the energy recovery during braking and while charging. Moreover, the battery cells have typically different charge levels depending on the degree of aging and manufacturing tolerances. For this reason, the CSSUs permanently monitor every single battery cell with regard to voltage and also temperature. These data will be processed in the battery management unit to offset the different charging states (balancing), and to ensure optimum battery performance.