An ECU in an electric power system for a vehicle controls a DC-DC converter so that an alternator transmits a residual generated electric power to a sub battery while a terminal voltage of a main battery is maintained within an optimally specified voltage range. A thin film having a particular color is attached to the side portion via the hot stamping system, which enables easy manufacture of the display apparatus having various colors of covers. A herbicidal spray composition is preparable from a particulate solid concentrate or a liquid concentrate. The output may take the form of exception-based printed or electronic reports, or the exception information may be relayed to a hand held device, preferably maintained by service personnel at the work site. While a series connection cable connected to the input port, the intelligent computer switch is determined to be a slave.