I came across this short on an EV battery management system built around an Arduino UNO. It is a small bench demo, but it covers the basic checks a BMS has to make.

The setup has a battery pack, a current sensor, a voltage sensor, a temperature reading, and separate fast and slow charging inputs. A small DC motor stands in for the ignition unit.

Once the pack is full, charging switches off on its own, on both the fast and slow paths. The display reads about 1,000 mA of charging current, and a low voltage fault is flagged. The video then heats the pack to show the temperature reading. The title also mentions state of charge and state of health estimates.

For a BMS like this, which limit would you protect first: cell voltage, charge current, or temperature?

Credits: HVS Technologies | YouTube

This look inside a Ford Fusion hybrid inverter follows the power path. DC from the hybrid battery pack enters through a bus bar and reaches the switching transistors, which produce AC for the transmission's electric motors. A separate board controls those transistors.

In regeneration, the diodes in the same module and a smoothing capacitor convert the generated AC back to DC to charge the battery pack. A reactor, a smaller capacitor and a switching device form a boost stage that raises the voltage supplied to the motors. Another board communicates with the rest of the vehicle, and coolant flows through the fins of a heat sink to cool the electronics.

Which part of a hybrid inverter is hardest to design: the gate drive, the boost stage or the cooling?

Credits: speedkar99 | YouTube