# US 11,079,441 B2 · Internal resistance estimating method, and secondary battery charging device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,079,441 B2 - Document ID: US11079441B2 - Status: Granted - Kind: B2 - Application number: 16/963,852 - Filed: 2019-06-04 - Published: 2021-03-25 - Granted: 2021-08-03 - Earliest claimed: 2018-06-05 - Assignees: Honda Motor Co., Ltd. - Applicants: Honda Motor Co., Ltd. - Inventors: Hirotaka Endo; Terumi Furuta; Mitsumoto Kawai - Web page: https://patentgrep.com/patent/US11079441B2 ## 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 31/387: Determining ampere-hour charge capacity or SoC - G01R 31/396: Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery - H01M 10/48: Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569) - H02J 7/00: Circuit arrangements for charging or discharging batteries or for supplying loads from batteries - Y02E 60/10: Energy storage using batteries - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract Provided is an internal resistance estimating method capable of estimating the internal resistance of a secondary battery, taking account of conditions when the secondary battery is being charged, without requiring progress information when the secondary battery is being used. The internal resistance estimating method for estimating the internal resistance of a secondary battery includes estimating an internal resistance Rd (Ts, Is, Va) on the basis of an internal resistance calculating formula, from an acquired internal resistance Rd (Ta, la, Va) of a battery, and estimating an internal resistance Rd (Ts, Is, Vs) from the estimated internal resistance Rd (Ts, Is, Va). ## Claims ### Claim 1 An internal resistance estimating method, comprising: an internal resistance acquiring step of acquiring an internal resistance of a first secondary battery when a first condition has a first value that is different from a predetermined first standard value and when a second condition has a second value that is different from a predetermined second standard value, wherein the first and second conditions are different conditions; a first internal resistance estimating step of, correcting the internal resistance by estimating an intermediate internal resistance of the first secondary battery in which the first condition has the first standard value and the second condition has the second value, the intermediate internal resistance estimated using an internal resistance calculation formula obtained by regarding the internal resistance of the first secondary battery as a function in which the first condition is a variable and performing a Taylor-expansion on the function around the first standard value; and a second internal resistance estimating step of correcting the intermediate internal resistance by estimating a new internal resistance of the first secondary battery in which the first condition has the first standard value and the second condition has the second standard value, the new internal resistance estimated based on an estimated capacity of the first secondary battery and on a capacity acquired in advance for a second secondary battery, wherein the second secondary battery has same specifications as the first secondary battery and a shorter usage period than the first secondary battery. ### Claim 2 (depends on 1) The internal resistance estimating method according to claim 1, wherein the internal resistance calculation formula includes at least a first-order partial differential term. ### Claim 3 (depends on 1) The internal resistance estimating method according to claim 1, wherein the internal resistance acquiring step includes acquiring the internal resistance of the first secondary battery based on a charging current when the first secondary battery is being charged and one charging voltage of the first secondary battery from among a charging start voltage and a charging end voltage, the first condition is at least one of a temperature and the charging current of the first secondary battery at a timing when the internal resistance of the first secondary battery is acquired, and the second condition is the voltage used when acquiring the internal resistance of the first secondary battery in the internal resistance acquiring step, from among the charging start voltage and the charging end voltage. ### Claim 4 (depends on 1) The internal resistance estimating method according to claim 1, wherein the internal resistance acquiring step includes estimating the internal resistance of the first secondary battery based on an internal resistance acquired in advance for the second secondary battery. ### Claim 5 (depends on 1) The internal resistance estimating method according to claim 1, comprising: a capacity estimating step of estimating the estimated capacity of the first secondary battery. ### Claim 6 (depends on 5) The internal resistance estimating method according to claim 5, comprising: a capacity acquiring step of acquiring a capacity of the first secondary battery when a third condition has a third condition value that differs from a predetermined third standard value, wherein the capacity estimating step includes correcting the capacity of the first secondary battery acquired in the capacity acquiring step by estimating the estimated capacity in which the third condition has the third standard value using a capacity calculation formula obtained by regarding the capacity of the first secondary battery as a function in which the third condition is a variable and performing a Taylor-expansion on the function around the third standard value. ### Claim 7 (depends on 6) The internal resistance estimating method according to claim 6, wherein the capacity calculation formula includes at least a first-order partial differential term. ### Claim 8 (depends on 6) The internal resistance estimating method according to claim 6, wherein the capacity acquiring step includes acquiring the capacity of the first secondary battery based on the charging current, the charging start voltage, and the charging end voltage, and the third condition is at least one of a temperature, the charging current, the charging start voltage, and the charging end voltage of the first secondary battery at a timing when the capacity of the first secondary battery is acquired. ### Claim 9 (depends on 1) The internal resistance estimating method according to claim 1, wherein the first secondary battery is a lithium-ion battery. ### Claim 10 (depends on 1) A secondary battery charging device that uses the internal resistance estimating method according to claim 1 to estimate an internal resistance of a first secondary battery.