Sub Battery Relay Control

Sub battery relay prevents a loss in supply voltage to each system due to a battery voltage loss during engine start and restart. EMCM turns OFF the sub battery relay to interrupt the connection between the main battery power supply circuit and the sub battery power supply circuit during the engine start and the restart. This protects the electric equipment connected to the sub battery power supply circuit from an impact (e.g. memory reset) of a loss in supply voltage. After the engine is started normally, EMCM turns ON the sub battery relay to connect the main battery power supply circuit and the sub battery power supply circuit. This allows the alternator to supply the generated power to all of the systems and to charge the main battery and sub battery.