EV Battery Capacity Calibration Using Onboard Charge-Discharge Cycles
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Solution Overview
Problem
Current methods for estimating the state of health and capacity of electric vehicle battery packs are inaccurate and complex, leading to incorrect range estimates and unnecessary maintenance requests, as they rely on cycling patterns and laboratory measurements that are not easily accessible to consumers.
Innovation Solution
A capacity determination methodology that involves charging and discharging the battery pack using on-board loads and external components, with a battery management system that processes metrics to provide a percentage-based characterization of battery capacity, enabling more accurate range estimation and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional battery capacity estimation methods are used, then battery state of health can be assessed, but the estimation accuracy is poor and the method complexity is high
Solution Approach 1:
The battery management system uses the vehicle's own onboard loads and charging infrastructure to perform capacity determination tests, eliminating the need for external laboratory equipment. The system self-diagnoses battery capacity by controlling charge/discharge cycles through available vehicle components, making the complex measurement process accessible without specialized external devices.
Solution Approach 2:
The system determines battery capacity by measuring actual charge and discharge parameters (current, voltage, time) during controlled cycles and comparing them to nominal parameters. This parameter-based approach provides accurate capacity estimation without requiring complex physical testing equipment, transforming a complex measurement problem into a parameter comparison calculation.
2Measurement precision
If accurate battery capacity measurement is performed using traditional methods, then precise state of health information can be obtained, but the process requires laboratory measurements that are not accessible to consumers
Solution Approach 1:
The battery capacity determination is performed using the vehicle's own onboard resources including battery management system, charging port, and vehicle loads. This self-service approach eliminates dependency on external laboratory facilities, allowing any vehicle owner to access battery capacity information through the vehicle's existing infrastructure without requiring specialized external equipment or facilities.
Solution Approach 2:
The battery management system serves multiple functions: it manages normal battery operations during vehicle use and simultaneously performs capacity determination tests using the same onboard components. The charging port and battery control unit serve both日常 charging functions and diagnostic testing functions, making the measurement capability universally accessible to all vehicle owners without requiring separate specialized equipment.
3Loss of time
If battery capacity is determined using onboard loads and external components, then real-time capacity assessment can be provided, but additional components are required
Solution Approach 1:
The battery management system and onboard loads serve dual purposes: they manage normal vehicle operations during everyday use and simultaneously function as testing equipment for capacity determination. The same battery control unit that manages charging also controls the discharge test cycles, and the same vehicle loads used during normal operation are utilized for capacity testing, eliminating the need for separate dedicated testing components.
Solution Approach 2:
The battery management system acts as an intermediary that coordinates between the charging infrastructure, onboard loads, and capacity calculation algorithms. It manages the charge/discharge cycles, monitors parameters, and processes the data to determine capacity, serving as a mediator that integrates existing components into a functional capacity assessment system without requiring complex additional hardware.
Data Source
AI summary
The present disclosure generally relates to systems and methods for managing a battery of an electric vehicle. In some embodiments, a system initiates battery discharging on a battery pack, where the battery discharging continues until the battery pack reaches a first threshold level of charge. The system then estimates a first state of charge of the battery pack based at least on a first sensor reading associated with the battery pack. The system initiates battery charging on the battery pack, where the battery charging continues until the battery pack reaches a second threshold level of charge. The system estimates a second state of charge of the battery pack based at least on a second sensor reading associated with the battery pack. The system generates a processing result that indicates a capacity of the battery pack based at least on the first state of charge and the second state of charge.