To accurately detect the remaining capacity of a battery without influence of the load state.
The voltage value of the battery is detected, and the using state of a telephone is detected (ST1, ST2). At the time of speaking state, reference values Vac, Vbc, Vcc in a speaking state are read from a ROM, while at the time of no speaking state, reference values Va, Vb, Vc of no speaking state are read from the ROM (ST3 to ST5). A load current increases in the speaking state, and a battery voltage is lowered by the internal resistance. Accordingly, the values Vac, Vbc, Vcc are respectively smaller than the values Va, Vb, Vc by a correction value. The voltage value of the battery is compared with the reference value to obtain the remaining information (compared result) of the battery (ST6). The display responsive to the information is conducted on a liquid crystal display unit (ST7). Since the reference value compared with the voltage value is altered so as to be smaller than the other state by the correction value in the speaking state for increasing the load current, the information for excluding the influence of the load state can be obtained.
SAITO TERU
OTAKE AKIRA
TAKESHIMA YOSHITO
TERADA RYOJI
