ELECTRIC POWER SUPPLY APPARATUS

The present invention provides an electric power supply apparatus that supplies power to an external load, characterized by comprising: a generator capable of generating electric power by motive power of an engine; a container capable of housing a battery; a first detector configured to detect a remaining amount of the battery housed in the container; a determining unit configured to determine a maximum amount of electric power that can be output from the electric power supply apparatus, on the basis of a result of detection by the first detector; and a notifying unit configured to notify a user of the maximum amount of electric power determined by the determining unit.