Abstract: The invention relates to a system (1) for cooling at least one motor vehicle battery (2), this system including: a closed compartment (3) arranged to receive a battery or battery cells (2), a dielectric fluid (4) present in the compartment so that it is able to cool the battery, a cooling device (5) arranged to cool the dielectric fluid, this cooling device including at least one channel in which a heat transfer fluid separate from the dielectric fluid can circulate, this cooling device including at least one inclined face for heat exchange between the dielectric fluid and the heat transfer fluid, this face (110) being arranged inclined relative to a horizontal direction when the system is mounted on the motor vehicle.