Super detailed diagram of Volt battery pack management design

　　At the heart of the Chevrolet Volt is a sophisticated battery management system that ensures the safety and reliability of the multi-cell lithium-ion battery pack. GM engineers have also established a 58% to 65% SoC safety window. This article illustrates Chevrolet's BMS design.

　　At the heart of the Chevrolet Volt is a sophisticated battery management system that ensures the safety and reliability of the multi-cell lithium-ion battery pack, which provides power on demand to the Volt's powertrain. In this management system, the battery monitoring board uses two key subsystems to monitor the condition of the battery cells and send digital results to a main processor, which coordinates the operation of the system. A signal interface isolates these subsystems and ensures insulation between the high-voltage battery detection circuits and the on-board communication devices.

　　Lithium-ion batteries maintain a nearly constant voltage output in the middle of their capacity range for a given temperature and output current—a characteristic that highlights the advantages of using lithium-ion batteries as a power source, but also complicates engineers' attempts to provide users with a battery's remaining capacity (or SoC, state of charge) using simple battery voltage measurements. For Volt drivers to estimate the car's range, accurate measurement of SoC is key. Keeping SoC within a specific range is also important to ensure that the battery has a long service life; batteries that maintain too high or too low a state of charge tend to degrade faster than batteries that maintain a moderate state of charge.

　　In the Volt, GM engineers have established a 58% to 65% SoC safety window. This window is based on different driving modes, with the lower limit of the normal driving mode set at 30% SoC; the upper limit of the mountain driving mode is set at 45% SoC. When the vehicle reaches a value close to the lower limit of SoC, the gasoline engine intervenes to extend the driving range. The battery interface control module board provides the required data to ensure that the Volt runs with a reliable SoC.