The “Electrostatic Charge Decay” (ECD) technique, previously introduced for electrical characterization of semi-insulating devices in electrophotography, involves open-circuit voltage measurements of corona charged layer as a function of time and/or position. The interpretation of data is based on first-principle charge transport theory. This provides information more relevant to the performance of the devices in electrophotographic applications. In the present work, the technique is extended by including the measurements of corona charging currents. The steady state values of charging current allow a more precise determination of charge injection properties. In addition, the key parameters can be consolidated into an effective resistance that can be used as a figure of merit for routine quality control purposes. Representative examples of characterization are presented for demonstration.