# US 10,502,791 B1 · System for determining an accurate ohmic resistance value associated with a battery cell

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- Number: US 10,502,791 B1
- Document ID: US10502791B1
- Status: Granted
- Kind: B1
- Application number: 16/120,667
- Filed: 2018-09-04
- Granted: 2019-12-10
- Earliest claimed: 2018-09-04
- Assignees: LG Chem, Ltd.
- Applicants: LG Chem, Ltd.
- Inventors: Xueyan Li; Kirk Stetzel; Chris Boylan; Nan Cao
- Web page: https://patentgrep.com/patent/US10502791B1

## CPC

- G01R 31/389: Measuring internal impedance, internal conductance or related variables
- G01R 31/367: Software therefor, e.g. for battery testing using modelling or look-up tables
- G01R 31/374: with means for correcting the measurement for temperature or ageing
- G01R 31/3842: combining voltage and current measurements
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A system for determining an accurate ohmic resistance value associated with a battery cell is provided. The system includes a microprocessor and a memory device. The memory device has a 3-D interpolation table with first, second, third, fourth, fifth, sixth, seventh, and eighth records, each having a respective SOC value, a respective temperature value, a respective current value, and a respective ohmic resistance value. The microprocessor performs a 3-D interpolation calculation based on a first SOC value, a first temperature value, and a first current value and each respective SOC value, each respective temperature value, and each respective current value in the records to determine the accurate ohmic resistance value associated with the battery cell.

## Claims

### Claim 1

A system for determining an accurate ohmic resistance value associated with a battery cell, comprising:
a current sensor generating a current signal indicative of an electrical current amplitude of an electrical current flowing through the battery cell;
a voltage sensor generating a voltage signal indicative of a voltage level of the battery cell;
a temperature sensor generating a temperature signal indicative of a temperature level of the battery cell;
a microprocessor determining a first current value based on the current signal, a first voltage value based on the voltage signal, a first temperature value based on the temperature signal, and a first SOC (State-Of-Charge) value based on a battery cell capacity value, the first voltage value and the first temperature value;
a memory device having a 3-D interpolation table stored therein with at least first, second, third, fourth, fifth, sixth, seventh, and eighth records, and each of the first, second, third, fourth, fifth, sixth, seventh, and eighth records having a respective SOC value, a respective temperature value, a respective current value, and a respective ohmic resistance value; and
the microprocessor performing a 3-D interpolation calculation based on the first SOC value, the first temperature value, the first current value, and each respective SOC value, each respective temperature value, and each respective current value in the first, second, third, fourth, fifth, sixth, seventh, and eighth records in the 3-D interpolation table to determine the accurate ohmic resistance value associated with the battery cell.

### Claim 2 (depends on 1)

The system of claim 1, wherein the microprocessor storing the accurate ohmic resistance value in a memory device.

### Claim 3 (depends on 1)

The system of claim 1, wherein the respective SOC value in the first record is different than the respective SOC value in the second record.

### Claim 4 (depends on 1)

The system of claim 1, wherein the respective SOC value in the first record is in a range of 35-55%.

### Claim 5 (depends on 1)

The system of claim 1, wherein the respective temperature value in the first record is different than the respective temperature value in the second record.

### Claim 6 (depends on 1)

The system of claim 1, wherein the respective temperature value in the first record is in a range of 0-10 degrees Celsius.

### Claim 7 (depends on 1)

The system of claim 1, wherein the respective current value in the first record is different than the respective current value in the second record.

### Claim 8 (depends on 1)

The system of claim 1, wherein the respective current value in the first record is in a range of 25-50 amps.

### Claim 9 (depends on 1)

The system of claim 1, wherein the temperature sensor is disposed on an external surface of the battery cell.

### Claim 10 (depends on 1)

The system of claim 1, wherein the voltage sensor is electrically coupled in parallel to the battery cell.

### Claim 11 (depends on 1)

The system of claim 1, wherein the current sensor is electrically coupled in series between the battery cell and an electrical load.

### Claim 12 (depends on 1)

The system of claim 1, wherein the first, second, third, fourth, fifth, sixth, seventh, and eighth records in the 3-D interpolation table define first, second, third, fourth, fifth, sixth, seventh, and eighth coordinate points, respectively, in a 3-D coordinate system.

### Claim 13 (depends on 12)

The system of claim 12, wherein the accurate ohmic resistance value corresponds to a ninth coordinate point within the 3-D coordinate system.

### Claim 14 (depends on 13)

The system of claim 13, wherein the ninth coordinate point is in a 3-D space defined by the first, second, third, fourth, fifth, sixth, seventh, and eighth coordinate points in the 3-D coordinate system.