Electric current protection circuit and method of using same

A protection device for protecting an electrical system in a vehicle, the electrical system including a battery pack having at least one contactor, and a high voltage bus connected to the battery pack, the protection device comprising:

• a microcontroller generates test pulses at a pulse output terminal thereof and includes a sense input terminal, the microcontroller having additional output terminals coupled to a control terminal of the at least one contactor;
• a first capacitor having a first terminal coupled to a first terminal of the at least one contactor;
• a second capacitor having a first terminal coupled to a second terminal of the at least one contactor;
• and
• circuitry coupled between the microcontroller and the first and second capacitors, the circuitry having an input terminal connected to the pulse output terminal of the microcontroller and an output terminal connected to the sense input terminal of the microcontroller, the circuitry reflecting the test pulses to the sense input terminal of the microcontroller if each contactor is open when the microcontroller applies a contactor opening voltage to the control terminal of the at least one contactor to open same, and presenting a signal different from the reflected test pulses to the sense input terminal of the microcontroller if any contactor is welded shut when the microcontroller applies the contactor opening voltage to the control terminal of the at least one contactor, the first and second capacitors being series connected and the at least one contactor providing an electrical connection between the first and second capacitors when the at least one contactor is closed and an open connection between the first and second capacitors when each contactor is opened.