Abstract: The voltage of a battery connected to a load is monitored to provide a continuous instantaneous indication of the voltage level of the battery and to provide an indication that the battery voltage has fallen to some critical level. Means are provided for generating a control signal which is representative of the battery voltage when the apparatus is operated in the battery testing mode and an independent voltage when the apparatus is operated in the self-testing mode. A first indicator means responsive to the control signal is provided for continually indicating the instantaneous level of the battery voltage when the apparatus is operating in the battery testing mode and the instantaneous level of the independent voltage when the apparatus is operating in the self-testing mode.

Abstract: The voltage of a battery connected to a load is automatically indicated with respect to two voltage levels. A first indicating means indicates that the battery voltage is greater than a first voltage level, and a second indicating means indicates that the battery voltage is less than the first voltage level but greater than a second voltage level. A third indicating means indicates that the battery voltage is less than both the first and second voltage levels and disables the load connected to the battery.Means are provided for selectively generating a control signal either in response to the battery voltage or at a decay rate independent of the battery voltage. In a normal operating mode, the control signal is determined by the actual decay rate of the battery voltage whereas, in a self-test mode, the control signal decays at a fixed decay rate independent of the actual battery voltage. The first, second and third indicating means operate in response to the control signal.