Printer

A printer for printing data onto a printing medium using a battery as a power source, comprising:

• a measuring device that measures a residual capacity of the battery;
• a display for displaying information related to the residual capacity of the battery;
• a printing head that performs the printing onto the printing medium based on the printing data;
• a platen roller that conveys the printing medium by rotating while holding the printing medium to the printing head;
• a motor that rotates the platen roller;
• a charging and discharging controller that supplies electric power to the printing head and the motor from the battery by controlling a charging and discharging of the battery;
• a memory that stores a predetermined residual capacity value of the battery in association with amount information indicating an amount of the printing medium that can be printed with printing data when the battery has the predetermined residual capacity value;
• and
• a processor that
• determines whether the residual capacity of the battery, as measured by the measuring device, is less than the predetermined residual capacity value,
• in a case where the processor determines that the residual capacity of the battery is not less than the predetermined residual capacity value, controls the charging and discharging controller such that normal electric power is supplied to at least the motor, and
• in a case where the processor determines that the residual capacity of the battery is less than the predetermined residual capacity value, controls the charging and discharging controller such that low electric power, which is lower than the normal electric power, is supplied to at least the motor, and controls the display to display the amount information associated with the predetermined residual capacity value in the memory as the information related to the residual capacity of the battery.