Power supply control device for electric vehicle

摘要

A power supply control device for an electric vehicle capable of reducing the power consumption in a battery monitor assembly adapted for monitoring a residual electric charge in a main battery 4. In response to an operation which causes increasing or decreasing the residual charge in the main battery 4, a start-up unit 200 produces a start-up demand pulse P3. Upon receiving the start-up demand pulse P3, a power supply controller circuit 60 closes a switch 59 to allow the power from a sub battery 5 to be supplied the battery monitor assembly 100. When the battery monitor assembly 100 is activated, its power supply maintaining means 102 delivers a self-hold signal S4 to maintain the switch 59 being closed. The battery monitor assembly 100 keeps monitoring the residual charge in the main battery 4 while it is energized by the sub battery 5.