Sensor with self supplied negative rail for battery pack measurement

A battery management system configured to couple to at least one battery module, the battery management system comprising:

• a first contact configured to couple between the at least one battery module and a machine;
• a resistor coupled in series with a second contact, wherein the resistor and the second contact are coupled in parallel with the first contact;
• a first sensor configured to sense a first electrical parameter of the at least one battery module, the first sensor comprising:
• an inverting charge pump coupled to receive a positive supply voltage and generate a first negative supply voltage;
• and
• a differential amplifier coupled to the at least one battery module and supplied by the positive supply voltage and the first negative supply voltage, the differential amplifier configured to generate an output representing the first electrical parameter;
• a second sensor coupled to a second side of the first contact, the second sensor configured to sense a second electrical parameter of the at least one battery module as seen by the machine, the second sensor comprising:
• an inverting charge pump coupled to receive a positive supply voltage and generate a second negative supply voltage;
• and
• a differential amplifier coupled to the at least one battery module and supplied by the positive supply voltage and the second negative supply voltage, the differential amplifier configured to generate an output representing the second electrical parameter;
• and
• a control circuit configured to receive corresponding outputs of the first sensor and second sensor and determine a value of the first electrical parameter and a value of the second electrical parameter.