# US 2013/0154672 A1 · Method and System for Battery Current Measurement Calibration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154672 A1 - Document ID: US20130154672A1 - Status: Published application - Kind: A1 - Application number: 13/668,377 - Filed: 2012-11-05 - Published: 2013-06-20 - Earliest claimed: 2011-12-16 - Assignees: Lear Corporation - Inventors: Antoni Ferre Fabregas; David Gamez Alari; Jose Gabriel Fernandez Banares - Web page: https://patentgrep.com/patent/US20130154672A1 ## CPC - G01R 31/382: Arrangements for monitoring battery or accumulator variables, e.g. SoC - G01R 35/005: {Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references (G01R33/0035, G01R35/002 take precedence)} - G01R 1/00: Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00 (constructional details particular to {electromechanical} arrangements for measuring the electric consumption G01R11/02) - G01R 1/203: {Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts (resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R)} - G01R 19/2503: {for measuring voltage only, e.g. digital volt meters (DVM's) (G01R19/2506 - G01R19/257 take precedence)} - H10P 95/00: Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract A sensor for monitoring battery current includes a shunt and a current source. The shunt has a resistance with an actual value. The current source is configured to provide a known value of current through the shunt. A controller is configured to generate a measured value of the current through the shunt as a function of a measured value of voltage drop across the shunt caused by the current through the shunt and an assumed value of the resistance of the shunt. The controller is further configured to detect the assumed value of the resistance of the shunt as being different than the actual value of the resistance of the shunt when the known and measured values of the current differ. ## Claims ### Claim 1 A sensor for monitoring battery current, the sensor comprising: a shunt having a resistance with an actual value; a current source configured to provide a known value of current through the shunt; and a controller configured to generate a measured value of the current through the shunt as a function of a measured value of voltage drop across the shunt caused by the current through the shunt and an assumed value of the resistance of the shunt; wherein the controller is further configured to detect the assumed value of the resistance of the shunt as being different than the actual value of the resistance of the shunt when the known and measured values of the current differ. ### Claim 2 (depends on 1) The sensor of claim 1 wherein: the controller is further configured to detect the assumed value of the resistance of the shunt as being the same as the actual value of the resistance of the shunt when the known and measured values of the current are the same. ### Claim 3 (depends on 1) The sensor of claim 1 further comprising: an analog-to-digital converter (ADC) electrically connected to a node which is connected to one end of the shunt, the ADC configured to generate the measured value of the voltage drop across the shunt caused by the current through the shunt. ### Claim 4 (depends on 1) The sensor of claim 1 wherein: the controller is further configured to generate a difference between the assumed and actual values of the resistance of the shunt as a function of a difference between the known and measured values of the current; wherein the controller is further configured to calibrate the assumed value of the resistance of the shunt based on the difference between the assumed and actual values of the resistance of the shunt. ### Claim 5 (depends on 1) The sensor of claim 1 wherein: the shunt is in series along a path having a battery such that battery current from the battery passes through the shunt; wherein the current source is configured to provide the current having the known value along an additional path to the shunt. ### Claim 6 (depends on 5) The sensor of claim 5 wherein: the controller is further configured to generate a difference between the assumed and actual values of the resistance of the shunt as a function of a difference between the known and measured values of the current; wherein the controller is further configured to calibrate the assumed value of the resistance of the shunt based on the difference between the assumed and actual values of the resistance of the shunt. ### Claim 7 (depends on 6) The sensor of claim 6 wherein: the controller is further configured to generate a measured value of the battery current through the shunt as a function of a measured value of voltage drop across the shunt caused by the battery current through the shunt and the calibrated assumed value of the resistance of the shunt. ### Claim 8 (depends on 1) The sensor of claim 1 wherein: the controller is further configured to calculate the known value of the current provided through the shunt independent of generating the measured value of the current through the shunt. ### Claim 9 (depends on 1) The sensor of claim 1 wherein: the current source includes a voltage source, a resistor having a known value of resistance, and a switch connected in series to provide the known value of current through the shunt; wherein the controller is further configured to calculate the known value of current provided through the shunt as a function of a measured voltage of the voltage source and the known value of the resistance of the resistor. ### Claim 10 (depends on 9) The sensor of claim 9 further comprising: an analog-to-digital converter (ADC) electrically connected to a node which is electrically connected between the voltage source and the resistor, the ADC configured to generate the measured value of the voltage of the voltage source. ### Claim 11 (depends on 1) The sensor of claim 1 wherein: the current source includes a resistor having a known value of resistance and a switch connected in series, the resistor connected at one end to the switch and connected at another end to a battery configured to supply power to an external load whereby the current source is enabled to provide the known value of current through the shunt; wherein the controller is further configured to calculate the known value of current provided through the shunt as a function of a measured voltage of the battery and the known value of the resistance of the resistor. ### Claim 12 (depends on 1) The sensor of claim 1 wherein: the current source includes a resistor having a known value of resistance and a switch connected in series, the current source further including a DC/DC converter, the resistor connected at one end to the switch and connected at another end to the DC/DC converter, the DC/DC converter connected to a battery configured to supply power to an external load whereby the current source is enabled to provide the known value of current through the shunt; wherein the controller is further configured to calculate the known value of current provided through the shunt as a function of a measured voltage of the DC/DC converter and the known value of the resistance of the resistor. ### Claim 13 (depends on 1) The sensor of claim 1 wherein: the current source includes a resistor having a known value of resistance and a switch connected in series, the current source further including an isolated DC/DC converter supplied from a low-voltage battery and the resistor being connected at one end to the switch and being connected at another end to the DC/DC converter whereby the current source is enabled to provide the known value of current through the shunt; wherein the controller is further configured to calculate the known value of current provided through the shunt as a function of a measured voltage of the DC/DC converter and the known value of the resistance of the resistor. ### Claim 14 (depends on 1) The sensor of claim 1 wherein: the current source includes a capacitor connected to a voltage source, a resistor having a known value of resistance, and a pair of switches connected in series to provide the known value of current through the shunt; wherein the controller is further configured to calculate the known value of current provided through the shunt as a function of a measured voltage of the capacitor and the known value of the resistance of the resistor. ### Claim 15 A method for monitoring battery current, the method comprising: injecting a known value of current through a shunt having a resistance with an actual value; generating a measured value of the current through the shunt as a function of a measured value of voltage drop across the shunt caused by the current through the shunt and an assumed value of the resistance of the shunt; and detecting the assumed value of the resistance of the shunt as being different than the actual value of the resistance of the shunt when the known and measured values of the current differ. ### Claim 16 (depends on 15) The method of claim 15 further comprising: detecting the assumed value of the resistance of the shunt as being the same as the actual value of the resistance of the shunt when the known and measured values of the current are the same. ### Claim 17 (depends on 15) The method of claim 15 further comprising: generating a difference between the assumed and actual values of the resistance of the shunt as a function of a difference between the known and measured values of the current; and calibrating the assumed value of the resistance of the shunt based on the difference between the assumed and actual values of the resistance of the shunt. ### Claim 18 (depends on 15) The method of claim 15 wherein: the shunt is in series along a path having a battery such that battery current from the battery passes through the shunt; the current having the known value is injected to the shunt along an additional path. ### Claim 19 (depends on 18) The method of claim 18 further comprising: generating a difference between the assumed and actual values of the resistance of the shunt as a function of a difference between the known and measured values of the current; calibrate the assumed value of the resistance of the shunt based on the difference between the assumed and actual values of the resistance of the shunt; and generating a measured value of the battery current through the shunt as a function of a measured value of voltage drop across the shunt caused by the battery current through the shunt and the calibrated assumed value of the resistance of the shunt. ### Claim 20 (depends on 15) The method of claim 15 further comprising: calculating the known value of the current provided through the shunt independent of generating the measured value of the current through the shunt.