Abstract: A power supply having a battery and a battery charger is disclosed which includes a discharge circuit for automatically measuring the battery charge without taking the battery out of service and without draining the battery below the minimum safe charge level necessary to operate a piece of equipment connected thereto. The discharge circuit automatically electrically isolates the battery from the charging circuit and measures the battery characteristics as the battery discharges across the equipment load. Once the battery charge is measured, the results are stored in non-volatile memory and the battery is automatically recharged.

Abstract: A battery charger circuit having a main transformer and a boost transformer. The main transformer supplies power to produce a DC main charging current at the circuit output for charging a battery. The boost transformer supplies power to produce a DC trickle charging current at the circuit output. The power rating of the boost transformer is a small percentage of that of the main transformer.