Battery preheating systems and methods in an aircraft hybrid electric powertrain

A hybrid powertrain system comprising:

• a combustion engine;
• a battery pack;
• a combustion engine coolant circuit;
• a battery pack coolant circuit;
• a heat exchanger configured to exchange heat between the combustion engine coolant circuit and the battery pack coolant circuit;
• at least one throttling device operatively connected to one of the combustion engine coolant circuit or the battery pack coolant circuit;
• and
• a controller configured to:
• transmit a signal to the at least one throttling device to adjust a flow of coolant through the heat exchanger of at least one of the combustion engine coolant circuit or the battery pack coolant circuit;
• and
• predictively adjust a battery pack temperature based on expected altitude and expected rate of climb/descent information.

A method for heating a battery pack of a hybrid powertrain system comprising:

• receiving temperature sensor information from a battery pack temperature sensor;
• determining, based at least in part on the temperature sensor information, that heat should be transferred to the battery pack to maintain the battery pack at a temperature above a predetermined threshold, wherein the determining that heat should be transferred to the battery pack further comprises determining an expected outside air temperature or expected altitude for a flight path of an aircraft that includes the hybrid powertrain system;
• and
• transmitting a signal to at least one throttling device to adjust a flow of combustion engine coolant or battery pack coolant through a heat exchanger, wherein:
• the combustion engine coolant flows through a combustion engine coolant circuit that includes a first side of the heat exchanger, and
• the battery pack coolant flows through a battery pack coolant circuit that includes a second side of the heat exchanger.