A bidirectional current-time integrator device comprises a shunt for connection in a circuit and an integrating circuit having inputs connected to opposite ends of the shunt through a switching device. The integrating circuit integrates an input signal from the shunt with time to produce a stream of pulses at a frequency proportional to the current with each pulse representing a given unit of current time. A bidirectional counter assembly counts the pulses from the integrating circuit in one direction when the current is in one direction, and in the opposite direction when the current reverses. The integrator circuit includes means for storing any partial unit of current time accumulated whenever the current direction changes and adding that partial unit to the subsequent accumulation of the signal when the current changes back to the original direction. The device may be used as a battery discharge state monitor.