The invention includes a circuit to monitor batteries arranged in a parallel battery configuration for charge/discharge battery circuit operation. The circuit selectively tests for each battery's presence in a battery holder or receptacle without interrupting circuit discharging operation, e.g., physical removal, and communicates a fault condition if the battery is determined to be missing. The inventive circuit enables existing or legacy control circuitry operating with the circuit to detect individual missing batteries where the legacy control circuitry is constructed to detect only missing circuit charge paths states.