Abstract: A battery-powered accessory monitors an output voltage reduction of the battery as well as the amount of transmitting/receiving data at all times. When a voltage drop of the battery is detected, the accessory displays communication information including the amount of data which have been sent or received by that time. The data transmission brings to a halt at the time when the battery voltage drop is detected. Since a user can easily obtain the communication information through the display, it is immediately determined whether all the data have been transmitted. Furthermore, the user can easily discriminate the data including possible errors due to the battery voltage drop from all the data received. After a battery is restored to a sufficient voltage, the data transmission is resumed automatically. The data may be retransmitted from the following data.

Abstract: In communication equipment which uses a battery as the power supply, when a controller increases the transmission power at a transmitter corresponding to a drop in the electric field intensity, the controller lowers, accompanying that operation, a reference voltage from a reference voltage source which is used for comparison with the battery voltage for the purpose of detecting a drop in the battery capacity. Therefore, even when the battery voltage is dropped due to an increase in the transmission output, the reference voltage is also lowered correspondingly, so that there will not occur an erroneous detection of drop in the battery capacity due to the drop in the battery voltage.