PURPOSE: To detect a battery service life by using 1st battery information informing a battery voltage drop and 2nd battery information informing a battery service life after a preset time from the connection of a battery elapses.
CONSTITUTION: When a voltage monitor circuit 3 detects a battery voltage drop due to consumption of a battery 2 in the communication operation, it is informed to a center via a telephone line 8 to inform the detection of the battery voltage drop thereby giving attention. When a set time in a storage circuit 4 elapses during consecutive communication operation, the service life of the battery 2 is informed to inform the service life termination of the battery 2 to the center. Upon the receipt of the data of the 2nd battery information, the center discriminates it that the battery service life of the data terminal equipment 1 of the sender expires and applies the required processing. Then the data terminal equipment is subjected to maintenance such as replacement of the battery with a new battery early to attain efficient system operation without hindrance in the system operation.
ITO KUNIAKI
NAKAKUBO KOICHI
OSHIMI HIROKI
SHIMADA SUNAO
