A heater is operable with a main power supply unit and a chargeable auxiliary power supplying unit. The heater includes a heater part having one or a plurality of heater elements to receive power from the main and auxiliary power supplying units, a detecting part to detect information related to the heater part, and a controller to vary an amount of power supplied from the auxiliary power supply unit to the heater part per unit time based on the information detected by the detecting part.