[en] This report constitutes the second of the two-phase approach for assessing the safety and operational aspects of battery charger and inverter aging in nuclear power plants. This work, conducted by Brookhaven National Laboratory (BNL) under the auspices of the US NRC Nuclear Plant Aging Research (NPAR) Program, evaluated operating experience data, nuclear power plant maintenance practices, and plant design information to determine the impact of battery charger and inverter aging on safety, and the methods which should be used to detect aging degradation and mitigate its effects. A naturally aged inverter and battery charger were tested at BNL to evaluate the naturally aged condition, the effectiveness of condition monitoring techniques, and the practicality of implementing selected maintenance and monitoring recommendations. Temperature monitoring, component parameter measurements, and the periodic observation of critical circuit waveforms are viable methods for monitoring aging degradation. A maintenance program for battery chargers and inverters is recommended. As described in this report, the maintenance program incorporates inspection, monitoring, testing and repair activities which should be performed to detect and mitigate aging effects, and thereby assure the operational readiness of this important equipment throughout the plant's operating life. 32 refs., 43 figs., 19 tabs