The Battery Disconnect Unit, or BDU, is a sub-unit inside/outside the battery pack in high-voltage electrical or hybrid systems.
It can be installed in the battery housing either in the “chocolate bar” in the cell pack or on top of the battery housing (so-called “penthouse” location).
This sub-unit is responsible for monitoring, activating, and deactivating the high-voltage battery system.
It (dis-)connects the battery to the vehicle’s high-voltage powertrain and charging systems. It also performs overcurrent / short circuits detection enabling related safety interruptions.