EXTINGUISHING BATTERY THERMAL RUNAWAY

A system (100) includes a stack (102) of battery cells (104) within a container (106). An interior space (108) of the container (106) is filled with a coolant in direct contact with the cells (104). There need be no intervening containers between the coolant in the interior space (108) of the container, and the cells (104). A method can include detecting a thermal runaway event in one or more of the cells (104), and admitting some of the coolant at a first pressure into the one or more cells (104) at a second pressure lower than the first pressure.