Patent ID: 7564223

Claim:
A high frequency battery charger for charging a target battery, comprising: a charging circuit including a high frequency transformer, a switch switching the high frequency transformer, a filter coupled to the high frequency transformer for passing a DC voltage signal and a controller providing a high frequency driving signal to the switch; measuring circuitry for measuring at least one of a voltage or a current at the target battery; and a microprocessor receiving the measured voltage or current and calculating diagnostics of the target battery based on at least one of the measured voltage or current, wherein the microprocessor is programmed to: provide a test current that is lower than a charging current from the battery charger to the target battery; detect if the test current is present at the target battery; indicate a fault if the test current is not detected at the target battery; and increase the test current a predetermined amount and return to the detecting step if the test current is detected at the target battery.