When the winter temperature is too low, the battery of electric vehicles will be broken life (capacity decay), weaken (performance decay), if this time charging will also lay the hidden danger of violent death (lithium precipitation caused by internal short circuit risk of thermal runaway). Therefore, when the temperature is too low, it is necessary to heat (or insulation). ThePTC coolant heater is mainly used for heating the passenger compartment, and defrosting and defogging the windows, or power battery thermal management battery preheating.