Battery Backup Power System for Electrical Appliances with Two Options of Primary Power Sources

Backup power system (BPS) compatible with two options of primary power sources; grid-connected power (AC) or solar PV -power (DC), to provide power to household appliances that comprises; a rechargeable battery bank, a charging-balancing circuit to keep the battery fully charged when power from the utility grid is available, a battery management circuit to optimize a voltage output of the system and protect individual batteries from overcharging thereby prolonging the operating lifetime of batteries, a relay switch circuit controlled by the main power source to change-over the load/appliances between direct link through bypassing the main power and the storage battery power when both options of main power are unavailable, three led indicators to display the battery status. Short circuit protection is provided to protect the backup power system from appliance short circuits, and to protect the batteries in the event of a short circuit within the system. The result shows the excellent utilization of the traditional BPS losses, wherein some appliances, the proposed topology can achieve about 99% power efficiency as compared with the traditional one.