Abstract: A method of operating an emergency power supply for an elevator cabin includes determining a remaining power supply capacity of an energy storage device of the emergency power supply, determining a power demand of an electrical consumer, and predicting how long the energy storage device is capable of providing the electrical consumer with power, based on the determined remaining power supply capacity and the determined power demand. An emergency power supply for an elevator cabin includes an energy storage device configured to provide emergency power to an electrical consumer in the elevator cabin, and a control unit. The control unit is configured to control operation of the energy storage device, determine a remaining power supply capacity of the energy storage device, determine a power demand of the electrical consumer, and predict an amount of time for which the energy storage device is able to power the electrical consumer.