Active thermal management systems with multi-purpose reservoirs for liquid immersion cooled battery assemblies

A motor vehicle, comprising:

• a vehicle body;
• a plurality of road wheels attached to the vehicle body;
• a traction motor attached to the vehicle body and operable to drive one or more of the road wheels to thereby propel the motor vehicle;
• a traction battery pack attached to the vehicle body and electrically connected to the traction motor, the traction battery pack including a battery case defining therein a liquid-tight immersion compartment containing a plurality of lithium-class battery cells at least partially submerged in a liquid immersion cooling (LIC) fluid;
• and
• an active thermal management (ATM) system, including:
• a coolant reservoir defining therein a single fluid compartment stowing therein the LIC fluid and vent gases emitted by the lithium-class battery cells;
• a coolant inlet manifold fluidly connecting the coolant reservoir to the battery case and configured to transfer the LIC fluid into the immersion compartment;
• a coolant outlet manifold fluidly connecting the battery case to a first location of the coolant reservoir and configured to transfer the LIC fluid out from the immersion compartment and into the single fluid compartment;
• an auxiliary vent manifold configured to selectively fluidly connect the battery case to a second location of the coolant reservoir, distinct from the first location, responsive to a predefined thermal event and thereby transfer the LIC fluid and the vent gases generated by the lithium-class battery cells from the immersion compartment into the single fluid compartment of the coolant reservoir;
• and
• a gas valve mounted onto a third location of the coolant reservoir, above the first and second locations, and configured to selectively evacuate therefrom the vent gases at a predefined internal reservoir pressure.

A method of assembling an active thermal management (ATM) system for regulating an operating temperature of a battery assembly, the battery assembly including a battery case with a liquid-tight immersion compartment containing a battery cell and configured to hold a liquid immersion cooling (LIC) fluid, the method comprising:

• receiving a coolant reservoir configured to stow therein both the LIC fluid and vent gases of the battery cell;
• fluidly connecting the coolant reservoir to the battery case via a coolant inlet manifold, the coolant inlet manifold configured to transfer the LIC fluid from the coolant reservoir into the immersion compartment;
• fluidly connecting the battery case to the coolant reservoir via a coolant outlet manifold, the coolant outlet manifold configured to transfer the LIC fluid out from the immersion compartment and into the coolant reservoir;
• selectively fluidly connecting the battery case to the coolant reservoir responsive to a predefined thermal event via an auxiliary vent manifold, the auxiliary vent manifold configured to transfer the LIC fluid and vent gases generated by the battery cell from the immersion compartment into the coolant reservoir;
• and
• fluidly connecting a gas valve to the coolant reservoir, the gas valve configured to selectively evacuate the vent gases from the coolant reservoir at a predefined internal reservoir pressure.