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Our project goal is to build a 300V [1] coupling circuit for the Idaho National Lab’s (INL) Impedance Measurement Box (IMB). The IMB is a device that determines the frequency spectrum of the internal impedance of a battery by measuring its impedance to various frequencies. The procedure involves the box outputting a sum of sines (SOS) signal into a battery, capturing its voltage response, and processing the voltage time record into an impedance spectrum. This allows the box to determine the internal impedance of the battery, which can be used to predict the battery’s life and other characteristics. [2]

The IMB is currently built to measure batteries of up to 50V. Our goal is to design and construct a circuit that will allow the box to measure batteries of up to 300V. This will be done through the use of a coupling circuit and a state machine. The coupling circuit will operate by using a high voltage capacitor and resistors to protect the IMB and allow it to measure the battery without the source voltage ever exceeding 30V, which is the max the future IMB is designed to safely handle