d. A millivolt meter (fig 5) is used to measure the DC voltage differential
between generator volts and battery volts. The millivolt meter momentary-on switch
connects the meter and range selector into the circuit to be monitored when held in
the ON position. Deflection to the left of zero indicates higher generator
voltage. Deflection to the right of zero indicates higher battery voltage. The
meter reads 0-900mV or 0-9V depending on the selector switch setting.