AUTOMOBILE TELEPHONE SYSTEM

摘要

PURPOSE:To prevent the consumption of an on-vehicle battery and to avoid unexpected full consumption of battery by applying charging to a charging battery when a voltage of the on-vehicle battery is a prescribed voltage or above regardless of on/off a power switch. CONSTITUTION:With an ignition switch S turned on, a battery voltage detection in a battery voltage detection circuit 2041 is started. When the battery voltage of a prescribed voltage or alove is detected by the battery voltage detection circuit 2041, a 1st battery power control switch 2042 and a 2nd battery power control switch 2044 are set to be ON respectively. A power voltage 13.7V from an on-vehicle battery B is supplied to a charging battery 109 of a portable radiotelephony set 100. A voltage detection circuit 117 detects the voltage of a power supply line 116 and when the portable radiotelephony set 100 is connected to an on-vehicle adaptor 200, the charging voltage 109 and the voltage control section 108 of the portable radiotelephony set 100 are disconnected and the charging battery 109 charged.