Present article describes the method of operative diagnostics of available capacity of the lead-acid accumulator (battery) at 10 or 20-h discharge mode. This method is developed on the basis of mathematical model of process of the discharge of the lead-acid accumulator. This allows calculating the available capacity of the accumulator (battery) on the basis of measurement of function of a response to the set short-term test signal without necessity of carrying out the control discharge of the battery.
