Battery pack having an integrated cooling system

A battery pack includes a first header including a first conduit, a second header including a second conduit, and an energy storage system including a plurality of energy storage cells arranged between the first header and the second header. A coolant plate is arranged between the first header and the second header and abuts the plurality of energy storage cells. The coolant plate including a coolant channel having a first end fluidically connected to the first conduit, a second end fluidically connected to the second conduit, and an intermediate portion defining a flow path.