Abstract: The invention concerns a device for reactivating an electric battery (B) which is no longer able to supply the required minimum amount of electrical power to a connected consumer unit because it was supercooled by frost. The object of the invention is to create a solution, at a justifiable cost of time and energy, which enables the consumer unit to operate as soon as possible or keep it operating after the effect of extremely low temperatures on the battery. According to the invention, the reactivation of the battery takes place by internally heating the electrolyte, which is achieved with the help of its own time-controlled current via the battery contacts, whereby a negligibly small electric output is transformed in the external circuit. To that end the high internal resistance during supercooling is utilized and works as an internal heating element. A reactive load (X) is advantageously connected to at least one inductive and/or capacitive element through the battery contacts (+,−).