1. Field of the Invention
The present invention relates to a battery-powered apparatus, a method of controlling the apparatus, a program for implementing the method, and a storage medium storing the program. In particular, the present invention relates to a battery-powered apparatus including a remaining battery level detecting circuit, a method of controlling the apparatus, a program for implementing the method, and a storage medium storing the program.
2. Description of the Related Art
Conventionally, there have been known some apparatuses such as cameras of the type which is powered by a battery disposed within the main body of the apparatus (hereinafter referred to as “the internal battery”) and a battery externally connected to the main body of the apparatus (hereinafter referred to as “the external battery”). If both the internal battery and the external battery are connected to the apparatus, using the external battery takes priority over using the internal battery.
In the apparatus of this type, one detecting circuit detects the remaining battery level of the internal battery and the remaining battery level of the external battery, and the guaranteed minimum voltage level for the main body of the apparatus is used as a criterion by which the detecting circuit determines whether to prohibit the use of each battery (see Japanese Laid-Open Patent Publication (Kokai) No. H07-140531, for example).
According to the above conventional art, however, since one detecting circuit detects the remaining battery level of the internal battery and the remaining battery level of the external battery, a difference between the impedance from the internal battery to the detecting circuit and the impedance from the external battery to the detecting circuit cannot be taken into consideration, resulting in a difference in end voltage between the internal voltage and the external voltage. For this reason, if the unusable voltage level is determined with reference to the internal battery, the capacity of the external battery cannot be effectively used.