# US 8,751,086 B2 · Online battery capacity estimation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,751,086 B2 - Document ID: US8751086B2 - Status: Granted - Kind: B2 - Application number: 13/590,533 - Filed: 2012-08-21 - Published: 2014-02-27 - Granted: 2014-06-10 - Earliest claimed: 2012-08-21 - Assignees: Ford Global Technologies, LLC - Applicants: Yonghua Li; Richard Dyche Anderson - Inventors: Yonghua Li; Richard Dyche Anderson - Web page: https://patentgrep.com/patent/US8751086B2 ## CPC - H01M 10/42: Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells (H01M10/60 takes precedence) - B60L 58/12: responding to state of charge [SoC] - G01R 31/367: Software therefor, e.g. for battery testing using modelling or look-up tables - G01R 31/3835: involving only voltage measurements - B60L 2240/545: Temperature - B60L 2240/547: Voltage - B60L 2240/549: Current - Y02E 60/10: Energy storage using batteries - Y02T 10/70: Energy storage systems for electromobility, e.g. batteries - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An electric vehicle includes a controller configured to estimate battery capacity in accordance with a first state of charge estimation, a charge integration, and a second state of charge estimation. The first and second state of charge estimations are in accordance with time and temperature constraints and are such that the estimated battery capacity has limited uncertainty. The controller is further configured to generate an output based on the estimated battery capacity. ## Claims ### Claim 1 An electric vehicle comprising: a controller programmed to monitor keyoff events and estimate battery capacity in accordance with a first state of charge (SOC) estimation, a charge integration, and a second SOC estimation; the first and second SOC estimations corresponding to respective first and second consecutive keyoff events and being in accordance with time and temperature constraints such that the SOC estimations are based on battery open circuit voltages; the controller being further configured to generate an output based on the estimated battery capacity. ### Claim 2 (depends on 1) The electric vehicle of claim 1, wherein the first SOC estimation is based on a first battery open circuit voltage measured not less than a first predetermined amount of time after the first keyoff event. ### Claim 3 (depends on 2) The electric vehicle of claim 2, wherein the first battery open circuit voltage is measured not more than a predetermined time limit after the first keyoff event. ### Claim 4 (depends on 2) The electric vehicle of claim 2, wherein the first battery open circuit voltage is measured when a battery temperature is not less than a minimum temperature calibration value. ### Claim 5 (depends on 2) The electric vehicle of claim 2 wherein the first battery open circuit voltage is measured when a battery temperature is not more than a maximum temperature calibration value. ### Claim 6 (depends on 2) The electric vehicle of claim 2, wherein the second SOC estimation is based on a second battery open circuit voltage measured not less than a second predetermined amount of time after the second keyoff event. ### Claim 7 (depends on 6) The electric vehicle claim 6 wherein the first battery open circuit voltage is measured when a battery temperature is a first temperature, the second battery open circuit voltage is measured when the battery temperature is a second temperature, a difference between the first and second temperatures being not more than a delta temperature calibration value. ### Claim 8 (depends on 2) The electric vehicle of claim 2, wherein the time and temperature constraints are selected from a group including (i) a first set of constraints to allow SOC estimations based on battery open circuit voltages, and (ii) a second set of constraints that is relaxed relative to the first set of constraints while still allowing SOC estimations based on battery open circuit voltages. ### Claim 9 (depends on 2) The electric vehicle of claim 2, wherein the second SOC estimation is based on a second battery open circuit voltage measured not less than a second predetermined amount of time after the second keyoff event, and wherein the controller includes a wakeup timer, the wakeup timer configured to awaken the controller after the second keyoff event. ### Claim 10 (depends on 1) The electric vehicle of claim 1, wherein the estimated battery capacity is subjected to an upper bound and a lower bound for allowed variation between a current estimated battery capacity and a previous estimated battery capacity. ### Claim 11 (depends on 1) The electric vehicle of claim 1, wherein the controller is further configured to avoid estimating battery capacity when a charge event occurs between the first and second SOC estimations. ### Claim 12 (depends on 1) The electric vehicle of claim 1, wherein the controller is further configured to permit estimating battery capacity when a cell balancing event occurs between the first and second SOC estimations. ### Claim 13 A method of controlling an electric vehicle, comprising: generating, by a controller, an output based on an estimated battery capacity based on a first state of charge (SOC) estimation, a charge integration, and a second SOC estimation; the first and second SOC estimations corresponding to respective first and second consecutive keyoff events and being in accordance with time and temperature constraints such that the SOC estimations are based on battery open circuit voltages. ### Claim 14 (depends on 13) The method of claim 13, wherein the first SOC estimation is based on a first battery open circuit voltage measured not less than a first predetermined amount of time after the first keyoff event. ### Claim 15 (depends on 14) The method of claim 14, wherein the first battery open circuit voltage is measured not more than a predetermined time limit after the first keyoff event. ### Claim 16 (depends on 14) The method of claim 14, wherein the first battery open circuit voltage is measured when a battery temperature is not less than a minimum temperature calibration value. ### Claim 17 (depends on 14) The method of claim 14 wherein the first battery open circuit voltage is measured when a battery temperature is not more than a maximum temperature calibration value.